Neglected tropical diseases (NTDs) are a diverse group of tropical infections that are common in low-income populations in

developing regions A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreeme ...

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

, and the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

. They are caused by a variety of

pathogens In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

, such as

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

es,

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

, and parasitic worms (

helminths Parasitic worms, also known as helminths, are large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other parasitic worms such as ...

). These diseases are contrasted with the "big three" infectious diseases (

HIV/AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ...

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...

, and

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...

), which generally receive greater treatment and research funding. In sub-Saharan Africa, the effect of neglected tropical diseases as a group is comparable to that of malaria and tuberculosis. NTD co-infection can also make HIV/AIDS and tuberculosis more deadly. Some treatments for NTDs are relatively inexpensive. For example, the treatment for

schistosomiasis Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody s ...

is US$0.20 per child per year. Nevertheless, in 2010 it was estimated that control of neglected diseases would require funding of between US$2 billion and $3 billion over the subsequent five to seven years. Some pharmaceutical companies have committed to donating all the drug

therapies A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis. As a rule, each therapy has indications and contraindications. There are many different ...

required, and

mass drug administration The administration of drugs to whole populations irrespective of disease status is referred to as mass drug administration (MDA). This article describes the administration of antimalarial drugs to whole populations an intervention which has been u ...

efforts (for example,

mass deworming Mass deworming, also called preventive chemotherapy, is the process of treating large numbers of people, particularly children, for helminthiasis (for example soil-transmitted helminths (STH)) and schistosomiasis in areas with a high prevalence ...

) have been successful in several countries. While preventive measures are often more accessible in the developed world, they are not universally available in poorer areas. Within

developed countries A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...

, neglected tropical diseases affect the very poorest in society. In the United States, there are up to 1.46 million families, including 2.8 million children, living on less than two dollars a day. In developed countries, the burdens of neglected tropical diseases are often overshadowed by other public health issues. However, many of the same issues put populations at risk in developed as well as developing nations. For example, other problems can stem from poverty which exposes individuals to the vectors of these diseases, such as lack of adequate

housing Housing, or more generally, living spaces, refers to the construction and assigned usage of houses or buildings individually or collectively, for the purpose of shelter. Housing ensures that members of society have a place to live, whether it ...

. Twenty neglected tropical diseases are prioritized by the

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...

(WHO), though other organizations define NTDs differently. Chromoblastomycosis and other deep

mycoses Fungal infection, also known as mycosis, is disease caused by fungi. Different types are traditionally divided according to the part of the body affected; superficial, subcutaneous, and systemic. Superficial fungal infections include common ti ...

scabies Scabies (; also sometimes known as the seven-year itch) is a contagious skin infestation by the mite ''Sarcoptes scabiei''. The most common symptoms are severe itchiness and a pimple-like rash. Occasionally, tiny burrows may appear on the skin ...

and other

ectoparasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

, and

snakebite A snakebite is an injury caused by the bite of a snake, especially a venomous snake. A common sign of a bite from a venomous snake is the presence of two puncture wounds from the animal's fangs. Sometimes venom injection from the bite may occu ...

envenomation were added to the list in 2017. These diseases are

common Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common, a central public park in Boston, Massachusetts * Cambridge Common, common land area in Cambridge, Massachusetts * Clapham Common, originally com ...

in 149 countries, affecting more than 1.4 billion people (including more than 500 million children) and costing developing economies billions of dollars every year. They resulted in 142,000 deaths in 2013—down from 204,000 deaths in 1990.

Reasons for neglect

The importance of neglected tropical diseases has been underestimated since many are

asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered asy ...

and have long

incubation period Incubation period (also known as the latent period or latency period) is the time elapsed between exposure to a pathogenic organism, a chemical, or radiation, and when symptoms and signs are first apparent. In a typical infectious disease, the i ...

s. The connection between death and a neglected tropical disease that has been latent for a long period of time is not often realized. Areas of high

endemicity In epidemiology, an infection is said to be endemic in a specific population or populated place when that infection is constantly maintained at a baseline level without extra infections being brought into the group as a result of travel or simi ...

are often in geographically isolated areas, making treatment and prevention much more difficult. These diseases have been overlooked because they mainly affect the poorest countries of the

developing world A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...

and because of the recent emphasis on decreasing the prevalence of

, and

. Far more resources are given to the "big three" diseases (HIV/AIDS, tuberculosis, and malaria) because of their higher mortality and public awareness rates. Neglected tropical diseases do not have a prominent cultural figure to champion the cause.

Stigma

Neglected tropical diseases are often associated with

social stigma Social stigma is the disapproval of, or discrimination against, an individual or group based on perceived characteristics that serve to distinguish them from other members of a society. Social stigmas are commonly related to culture, gender, rac ...

, making their treatment more complex. Public health research has only recently begun to focus on stigma as a component of the issue. From the 1960s onward, approximately one citation a year related to social stigma. In 2006, there were 458. Disease control is greatly affected by this stigma, as it decreases help-seeking and treatment adherence. Disease control programs, starting as early as the 1980s, have begun to integrate stigma mitigation into their offerings. In India, the

leprosy Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria ''Mycobacterium leprae'' or ''Mycobacterium lepromatosis''. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This nerve damag ...

program prioritized the message that "leprosy is curable, not hereditary" in order to inspire optimism in highly affected communities. The goal was to make leprosy a disease "like any other", so as to reduce stigma. At the same time, medical resources available in the area were optimized to fulfill the curable promise made.

Economic incentives

Neglected tropical diseases are not commercial, and consequently, patents and profit play no role in stimulating innovation. Like all non-commercial areas, these diseases are the responsibility of governments and philanthropy (including industry philanthropy). Currently, the pharmaceutical industry views

research and development Research and development (R&D or R+D), known in Europe as research and technological development (RTD), is the set of innovative activities undertaken by corporations or governments in developing new services or products, and improving existi ...

as highly risky. For this reason, resources are not often put into the field of NTDs (as diseases of the poor) and new chemical products are often expensive. A review of public and private initiatives found that of the 1393 new chemical products that were marketed in the period between 1975 and 1999, only 16 were related to tropical diseases and tuberculosis. The same review additionally found that there was a 13-fold greater chance of a drug entering the market being for

central nervous The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

system disorders or

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

than an NTD. Due to a lack of economic incentives for the pharmaceutical industry, successful NTD treatment programs have often relied on donations. The Mectizan Donation Program has donated over 1.8 billion tablets of

ivermectin Ivermectin (, '' EYE-vər-MEK-tin'') is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, today it is used to treat inf ...

. While developed countries will often rely on government-run and private partnerships to fund such projects, developing nations frequently have significantly lower per-person spending on these diseases. A 2006 report found that the

Gates Foundation The Bill & Melinda Gates Foundation (BMGF), a merging of the William H. Gates Foundation and the Gates Learning Foundation, is an American private foundation founded by Bill Gates and Melinda French Gates. Based in Seattle, Washington, it was ...

funded most extra activity to counter these diseases.

Developed nations

Since 2008, the concept of "neglected diseases of poverty" has been developed and explored. This group of diseases overlaps with the neglected tropical diseases, which also pose a threat to human health in developed nations. In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

alone, there are at least 12 million people with these neglected parasitic infections. They make up a hidden disease burden among the poorest of wealthy societies. In developed nations, lack of knowledge in the healthcare industry and lack of conclusive diagnostic tests perpetuate the neglect of this group of diseases. In the United States, high rates of parasitic infection can be distributed along geographic, racial, and socio-economic lines. Within the African-American community, there may be up to 2.8 million cases of

toxocariasis Toxocariasis is an illness of humans caused by the dog roundworm ('' Toxocara canis'') and, less frequently, the cat roundworm (''Toxocara cati'').https://academic.oup.com/ajcp/article/142/suppl_1/A104/1771175 Eosinophilic Pseudoleukemia Due to T ...

. Rates of toxocariasis,

trichomoniasis Trichomoniasis (trich) is an infectious disease caused by the parasite ''Trichomonas vaginalis''. About 70% of affected people do not have symptoms when infected. When symptoms occur, they typically begin 5 to 28 days after exposure. Symptoms ca ...

, and other neglected infections occur in the United States at the same rate as in

Nigeria Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...

. Within the

Hispanic The term ''Hispanic'' ( es, hispano) refers to people, Spanish culture, cultures, or countries related to Spain, the Spanish language, or Hispanidad. The term commonly applies to countries with a cultural and historical link to Spain and to Vic ...

community, neglected infections are concentrated near the US–Mexico border. Vector-borne illnesses are especially high, with some rates approaching those of Latin America.

Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily ''Triatominae'', known as "kissing bugs". The symptoms change over the cou ...

was found in the US as early as the 1970s. However, in the developed world, diseases that are associated with poverty are often not addressed comprehensively. This may be due to a lack of economic incentives and public policy failings. Here, a lack of awareness prevents effective policy generation and leaves healthcare services unequipped to address the issue. Additionally, there is little effort put into taking and maintaining large data sets on neglected diseases in the United States and other developed nations. The first summit on the issue was held by the Adler Institute on Social Exclusion in the United States in 2009. In Europe, a similar trend is seen. Neglected tropical diseases are concentrated in eastern and southern Europe, where poverty levels are the highest. The most prevalent diseases in this region are

ascariasis Ascariasis is a disease caused by the parasitic roundworm ''Ascaris lumbricoides''. Infections have no symptoms in more than 85% of cases, especially if the number of worms is small. Symptoms increase with the number of worms present and may in ...

trichuriasis Trichuriasis, also known as whipworm infection, is an infection by the parasitic worm ''Trichuris trichiura'' (whipworm). If infection is only with a few worms, there are often no symptoms. In those who are infected with many worms, there may b ...

, zoonotic helminth infections, and visceral leishmaniasis. Migration paths to Europe, most notably to Spain, have brought diseases to Europe as well. As many as 6,000 cases of Chagas disease have been introduced via this method. In response to a growing awareness of the burden on these populations, the

European Centre for Disease Prevention and Control The European Centre for Disease Prevention and Control (ECDC) is an agency of the European Union (EU) whose mission is to strengthen Europe's defences against infectious diseases. It covers a wide spectrum of activities, such as: surveillance, ...

has laid out ten public health guidelines. They cover a variety of topics, from

health education Health education is a profession of educating people about health. Areas within this profession encompass environmental health, physical health, social health, emotional health, intellectual health, and spiritual health, as well as sexual and r ...

and promotion to community partnerships and the development of a minority healthcare workforce.

List of diseases

There is some debate among the

WHO Who or WHO may refer to: * Who (pronoun), an interrogative or relative pronoun * Who?, one of the Five Ws in journalism * World Health Organization Arts and entertainment Fictional characters * Who, a creature in the Dr. Seuss book '' Horton He ...

CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...

, and

infectious disease An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

experts over which diseases are classified as neglected tropical diseases. Feasey, a researcher in neglected tropical diseases, notes 13 neglected tropical diseases:

Buruli ulcer Buruli ulcer () is an infectious disease characterized by the development of painless open wounds. The disease is limited to certain areas of the world, most cases occurring in Sub-Saharan Africa and Australia. The first sign of infection is a s ...

dracunculiasis Dracunculiasis, also called Guinea-worm disease, is a parasitic infection by the Guinea worm, ''Dracunculus medinensis''. A person becomes infected by drinking water containing water fleas infected with guinea worm larvae. The worms penetrate t ...

hookworm Hookworms are intestinal, blood-feeding, parasitic roundworms that cause types of infection known as helminthiases. Hookworm infection is found in many parts of the world, and is common in areas with poor access to adequate water, sanitation, an ...

infection, human

African trypanosomiasis African trypanosomiasis, also known as African sleeping sickness or simply sleeping sickness, is an insect-borne parasitic infection of humans and other animals. It is caused by the species ''Trypanosoma brucei''. Humans are infected by two typ ...

, Leishmaniasis,

lymphatic filariasis Lymphatic filariasis is a human disease caused by parasitic worms known as filarial worms. Usually acquired in childhood, it is a leading cause of permanent disability worldwide. While most cases have no symptoms, some people develop a syndrome ...

onchocerciasis Onchocerciasis, also known as river blindness, is a disease caused by infection with the parasitic worm ''Onchocerca volvulus''. Symptoms include severe itching, bumps under the skin, and blindness. It is the second-most common cause of blindne ...

trachoma Trachoma is an infectious disease caused by bacterium ''Chlamydia trachomatis''. The infection causes a roughening of the inner surface of the eyelids. This roughening can lead to pain in the eyes, breakdown of the outer surface or cornea of ...

, and

. Fenwick recognizes 12 "core" neglected tropical diseases: the same as above, excluding hookworm. These diseases result from four different classes of causative

: (i)

(for Chagas disease, human African

trypanosomiasis Trypanosomiasis or trypanosomosis is the name of several diseases in vertebrates caused by parasitic protozoan trypanosomes of the genus ''Trypanosoma''. In humans this includes African trypanosomiasis and Chagas disease. A number of other diseas ...

, and leishmaniases); (ii)

(for Buruli ulcer, leprosy, trachoma, and yaws), (iii)

metazoan Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...

worms (for cysticercosis/taeniasis, dracunculiasis, echinococcosis, foodborne trematodiases, lymphatic filariasis, onchocerciasis, schistosomiasis, and

soil-transmitted helminthiasis Soil-transmitted helminthiasis is a type of helminth infection (helminthiasis) caused by different species of roundworms. It is caused specifically by those worms which are transmitted through soil contaminated with faecal matter and are therefor ...

); and (iv)

es (dengue and chikungunya, rabies). The World Health Organization recognizes the twenty diseases below as neglected tropical diseases. The

's 2010 report dedicated to neglected tropical diseases offers an expanded list including

dengue Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...

rabies Rabies is a viral disease that causes encephalitis in humans and other mammals. Early symptoms can include fever and tingling at the site of exposure. These symptoms are followed by one or more of the following symptoms: nausea, vomiting, vi ...

yaws Yaws is a tropical infection of the skin, bones, and joints caused by the spirochete bacterium ''Treponema pallidum pertenue''. The disease begins with a round, hard swelling of the skin, in diameter. The center may break open and form an ulce ...

cysticercosis Cysticercosis is a tissue infection caused by the cysticercus, young form of the Taenia solium, pork tapeworm. People may have few or no symptoms for years. In some cases, particularly in Asia, solid lumps of between one and two centimetres may ...

echinococcosis Echinococcosis is a parasitic disease of tapeworms of the ''Echinococcus'' type. The two main types of the disease are ''cystic echinococcosis'' and '' alveolar echinococcosis''. Less common forms include ''polycystic echinococcosis'' and ''uni ...

, and foodborne trematode infections.World Health Organization. Working to overcome the global impact of neglected tropical diseases: first WHO report on neglected tropical diseases. 2010. ND=Not DeterminedHotez PJ, Molyneux DH, Fenwick A, Ottesen E, Ehrlich Sachs S, Sachs JD. Incorporating a rapid-impact package for neglected tropical diseases with programs for HIV/AIDS, tuberculosis, and malaria. ''PLoS Med'' 2006 Jan;3(5):e102.Hotez PJ, Molyneux DH, Fenwick A, Kumaresan J, Sachs SE, Sachs JD, et al. Control of neglected tropical diseases. ''N Engl J Med'' 2007 Sep 6;357(10):1018-1027.

Buruli ulcer

is caused by the bacterium ''

Mycobacterium ulcerans ''Mycobacterium ulcerans'' is a species of bacteria found in various aquatic environments. The bacteria can infect humans and some other animals, causing persistent open wounds called Buruli ulcer. ''M. ulcerans'' is closely related to '' Mycob ...

''. It is related to the family of organisms that cause

and

, but ''Mycobacterium ulcerans'' produces a toxin, mycolactone, that destroys tissue. The prevalence of Buruli ulcer is unknown. The risk of mortality is low, although secondary infections can be lethal. Morbidity takes the form of deformity, disability, and skin lesions, which can be prevented through early treatment and treated with antibiotics and surgery. It is found in Africa, Asia, and Latin America.

Chagas disease

is also known as

American trypanosomiasis Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily ''Triatominae'', known as "kissing bugs". The symptoms change over the cou ...

. There are approximately 15 million people infected with Chagas disease. Morbidity rates are higher for immuno-compromised individuals, children, and the elderly, but can be very low if treated early. Chagas disease does not kill victims rapidly, instead causing years of debilitating chronic symptoms. It is caused by a

vector-borne In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen to another living organism; agents regarded as vectors are organisms, such as Parasitism, parasites or Microorganism, microbes. The first major ...

protozoa and spread by contact with ''

Trypanosoma cruzi ''Trypanosoma cruzi'' is a species of parasitic euglenoids. Among the protozoa, the trypanosomes characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood of ...

''-infected feces of the triatomine (

assassin Assassination is the murder of a prominent or VIP, important person, such as a head of state, head of government, politician, world leader, member of a royal family or CEO. The murder of a celebrity, activist, or artist, though they may not ha ...

) bug. The protozoan can enter the body via the bug's bite, skin breaks, or mucous membranes. Infection can result from eating infected food and coming into contact with contaminated bodily fluids. There are two phases of Chagas disease. The acute phase is usually asymptomatic. The first symptoms are usually skin

chancre A chancre ( )chancres
thefreedictionary is a painless

s, unilateral purplish orbital

oedema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...

, local lymphadenopathies, and

fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...

accompanied by a variety of other symptoms depending on the infection site. The chronic phase occurs in 30 percent of total infections and can take three forms, which are asymptomatic (most prevalent), cardiac, and digestive lesions. Chagas disease can be prevented by avoiding insect bites through insecticide spraying, home improvement, bed nets, hygienic food, medical care, laboratory practices, and testing. It can be treated with medication, although these may have severe side effects. It can be diagnosed through a

serological Serology is the scientific study of serum and other body fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum. Such antibodies are typically formed in response to an infection (against a given mi ...

test, although the test is not very accurate.

Dengue and chikungunya

There are 50–100 million

dengue virus ''Dengue virus'' (DENV) is the cause of dengue fever. It is a mosquito-borne, single positive-stranded RNA virus of the family ''Flaviviridae''; genus ''Flavivirus''. Four serotypes of the virus have been found, a reported fifth has yet to be co ...

infections annually.

Dengue fever Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characterist ...

is usually not fatal, but infection with one of four serotypes can increase later susceptibility to other serotypes, resulting in a potentially fatal disease called severe dengue. Dengue fever is caused by a

flavivirus ''Flavivirus'' is a genus of positive-strand RNA viruses in the family ''Flaviviridae''. The genus includes the West Nile virus, dengue virus, tick-borne encephalitis virus, yellow fever virus, Zika virus and several other viruses which may cau ...

, and is spread mostly by the bite of the ''

Aedes aegypti ''Aedes aegypti'', the yellow fever mosquito, is a mosquito that can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito can be recognized by black and white markings on its legs ...

'' mosquito. No treatment for either dengue or severe dengue exists beyond

palliative care Palliative care (derived from the Latin root , or 'to cloak') is an interdisciplinary medical caregiving approach aimed at optimizing quality of life and mitigating suffering among people with serious, complex, and often terminal illnesses. Wit ...

. The symptoms are high fever and flu-like symptoms. It is found in Asia, Latin America, and Northern Australia.

Chikungunya Chikungunya is an infection caused by the ''Chikungunya virus'' (CHIKV). Symptoms include fever and joint pains. These typically occur two to twelve days after exposure. Other symptoms may include headache, muscle pain, joint swelling, and a ra ...

is an arboviral disease transmitted by '' A. albopictus'' and '' A. aegypti'' mosquitoes. The virus was first isolated from an outbreak in Tanzania in 1952.

Chikungunya virus Chikungunya is an infection caused by the ''Chikungunya virus'' (CHIKV). Symptoms include fever and joint pains. These typically occur two to twelve days after exposure. Other symptoms may include headache, muscle pain, joint swelling, and a ra ...

is a member of the genus ''

Alphavirus ''Alphavirus'' is a genus of RNA viruses, the sole genus in the ''Togaviridae'' family. Alphaviruses belong to group IV of the Baltimore classification of viruses, with a positive-sense, single-stranded RNA genome. There are 32 alphaviruses ...

'' and family ''Togaviridae''. The word "chikungunya" is from the

Makonde language Makonde, or Kimakonde, is the language spoken by the Makonde, an ethnic group in southeast Tanzania and northern Mozambique. Makonde is a central Bantu language closely related to Yao. The Matambwe (Matembwe) and Mabiha (Maviha) dialects are ...

and means "that which bends up", referring to the effect of the debilitating joint pain on the patient. Symptoms, generally appearing 5–7 days after exposure, can be confused with dengue and include fever, rash, headache, joint pain, and swelling. The disease mainly occurs in Africa and Asia.

Dracunculiasis

Dracunculiasis Dracunculiasis, also called Guinea-worm disease, is a parasitic infection by the Guinea worm, ''Dracunculus medinensis''. A person becomes infected by drinking water containing water fleas infected with guinea worm larvae. The worms penetrate t ...

is also known as Guinea-worm disease. In 2019, 53 cases were reported across four countries, a substantial decrease from 3,500,000 cases in 1986. It is not fatal, but can cause months of inactivity. It is caused by drinking water contaminated by

water fleas The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more ...

infected with guinea-worm larvae. Approximately one year after infection, a painful blister forms and one or more worms emerge. Worms can be up to 1 metre long. It is usually treated by World Health Organization volunteers who clean and bandage wounds caused by worms and return daily to pull the worm out a few more inches. Dracunculiasis is preventable by water filtration, immediate case identification to prevent the spread of disease, health education, and treating ponds with larvicide. An eradication program has been able to reduce prevalence. , the four endemic countries are Chad, Ethiopia, Mali, and South Sudan.

Echinococcosis

The rate of

is higher in rural areas, and there are more than one million people infected currently. Untreated alveolar echinococcosis is fatal. It is caused by ingesting

parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

in animal feces. There are two versions of the disease: cystic and alveolar. Both versions involve an asymptomatic incubation period of several years. In the cystic version, liver cysts cause abdominal pain, nausea, and vomiting while cysts in the lungs cause chronic cough, chest pain, and shortness of breath. In alveolar echinococcosis, a primary cyst develops, usually in the liver, in addition to weight loss, abdominal pain, general feeling of ill health, and signs of liver failure. Surgery and drugs can both be used to treat echinococcosis. It can be prevented by deworming dogs, sanitation, proper disposal of animal feces, health education, and livestock vaccination. Cystic echinococcosis is found in the eastern portion of the Mediterranean region, northern Africa, southern and eastern Europe, the southern portion of South America, and Central Asia. Alveolar echinococcosis is found in western and northern China, Russia, Europe, and northern North America. It can be diagnosed through imaging techniques and serological tests.

Yaws

There are limited data available on the prevalence of

, although it primarily affects children. The mortality risk is very low, but the disease causes disfigurement and disability if untreated. The most common symptom is skin lesions. It is a chronic bacterial infection, transmitted by skin contact, and caused by the

spirochete A spirochaete () or spirochete is a member of the phylum Spirochaetota (), (synonym Spirochaetes) which contains distinctive diderm (double-membrane) gram-negative bacteria, most of which have long, helically coiled (corkscrew-shaped or s ...

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

Treponema pallidum ''Treponema pallidum'', formerly known as ''Spirochaeta pallida'', is a spirochaete bacterium with various subspecies that cause the diseases syphilis, bejel (also known as endemic syphilis), and yaws. It is transmitted only among humans. It is ...

pertenue''. It is treated with antibiotics and can be prevented through improved hygiene and sanitation. Yaws is most prevalent in the warm, moist, tropical regions of the Americas, Africa, Asia, and the Pacific.

Foodborne trematodiases

The foodborne trematode infections include

clonorchiasis Clonorchiasis is an infectious disease caused by the Chinese liver fluke (''Clonorchis sinensis'') and two related species. Clonorchiasis is a known risk factor for the development of cholangiocarcinoma, a neoplasm of the biliary system. Sympt ...

opisthorchiasis Opisthorchiasis is a parasitic disease caused by certain species of genus '' Opisthorchis'' (specifically, '' Opisthorchis viverrini'' and '' Opisthorchis felineus''). Chronic infection may lead to cholangiocarcinoma, a cancer of the bile ducts. ...

fascioliasis Fasciolosis is a helminth, parasitic worm infection caused by the common liver fluke ''Fasciola hepatica'' as well as by ''Fasciola gigantica''. The disease is a plant-borne Trematoda, trematode zoonosis, and is classified as a Neglected tropic ...

, and

paragonimiasis Paragonimiasis is a food-borne parasitic disease caused by several species of lung flukes belonging to genus '' Paragonimus''. Infection is acquired by eating crustaceans such as crabs and crayfishes which host the infective forms called metacerc ...

. These infections are all zoonotic, primarily affecting domestic or wild animals, but can also be transmitted to humans. They are acquired by eating food, such as raw fish, contaminated with the larval stages of the parasites. At least 40 million people are thought to be infected. Fasciola hepatica

Human African trypanosomiasis

(African sleeping sickness) is a somewhat rare

l disease as there are fewer than 10,000 cases currently. Human African trypanosomiasis is

and spreads through the bite of the

tsetse fly Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glo ...

. The most common symptoms are fever, headache, lymphadenopathy, nocturnal sleeping pattern, personality changes, cognitive decline, and coma. The disease is always fatal if untreated. The current forms of treatment are highly toxic and ineffective as resistance is spreading. It is diagnosed through an inexpensive

test.

Leishmaniasis

The three forms of leishmaniasis, a protozoal disease, are visceral ( Kala-azar), cutaneous, and mucocutaneous. There are an estimated 12 million people infected. It is fatal if untreated and 20,000 deaths from visceral leishmaniasis occur annually. It is a

disease that is caused by the bite of

sandflies Sandfly (or sand fly) is a colloquial name for any species or genus of flying, biting, blood-sucking dipteran (fly) encountered in sandy areas. In the United States, ''sandfly'' may refer to certain horse flies that are also known as "greenhe ...

. At least 90 percent of visceral leishmaniasis occurs in Bangladesh, Brazil, Ethiopia, India, South Sudan, and Sudan. Cutaneous leishmaniasis occurs in Afghanistan, Algeria, Brazil, Colombia, Iran, Pakistan, Peru, Saudi Arabia, and Syria. Around 90 percent of mucocutaneous leishmaniasis occurs in Bolivia, Brazil, and Peru. The only method of prevention is a vaccine that is under development and prevention of sandfly bites. Diagnosis can be made by identifying clinical signs, serological tests, or parasitological tests. Leishmaniasis can be treated with expensive medications.

Leprosy

According to recent figures from the WHO, 208,619 new cases of

were reported in 2018 from 127 countries. It is most prevalent in India (69% of cases), Brazil, Indonesia, Nigeria, the Democratic Republic of the Congo, Madagascar, and East Africa, from Mozambique to Ethiopia, with the highest relative incidence in India, Brazil, and Nepal. There are one to two million individuals currently disabled or disfigured due to past or present leprosy. It is caused by bacteria and transmitted through droplets from the mouth and nose of infected individuals. Leprosy causes disfigurement and physical disabilities if untreated. It is curable if treated early. Treatment requires multidrug therapy. The BCG vaccine has some preventative effect against leprosy. Leprosy has a 5–20 year incubation period, and the symptoms are damage to the skin, nerves, eyes, and limbs. Leprosy deformities hands

Lymphatic filariasis

Lymphatic filariasis is also known as

elephantiasis Elephantiasis is the enlargement and hardening of limbs or body parts due to tissue swelling. It is characterised by edema, hypertrophy, and fibrosis of skin and subcutaneous tissues, due to obstruction of lymphatic vessels. It may affect the genit ...

. There are approximately 120 million individuals infected and 40 million with deformities. Approximately two-thirds of cases are in Southwest Asia and one-third in Africa. Lymphatic filariasis is rarely fatal. Lymphatic filariasis has lifelong implications, such as lymphoedema of the limbs, genital disease, and painful recurrent attacks. Most people are asymptomatic, but have lymphatic damage. Up to 40 percent of infected individuals have kidney damage. It is a

disease, caused by nematode worms that are transmitted by mosquitoes. It can be treated with cost-effective antihelminthic treatments, and washing skin can slow or even reverse damage. It is diagnosed with a finger-prick blood test.

Onchocerciasis

Onchocerca volvulus emerging from a black fly

Onchocerciasis Onchocerciasis, also known as river blindness, is a disease caused by infection with the parasitic worm ''Onchocerca volvulus''. Symptoms include severe itching, bumps under the skin, and blindness. It is the second-most common cause of blindne ...

is also known as "river blindness". There are 20.9 million people infected and prevalence is higher in rural areas. Over 99 percent of cases are in sub-Saharan Africa. It causes blindness, skin rashes, lesions, intense itching, and skin depigmentation. It is a

disease, caused by filarial worm infected blackflies. It can be treated with

. It can be prevented by insecticide spraying or preventative dosing with ivermectin. The symptoms are generally itching and skin lesions.

Rabies

There are two forms of

: furious and paralytic. There are 60,000 deaths from rabies annually. It is mostly found in Asia and Africa. There is a higher prevalence in rural areas and it disproportionately affects children. Rabies is fatal after symptoms develop. It is caused by a

lyssavirus ''Lyssavirus'' (from the Greek ''lyssa'' "rage, fury, rabies" and the Latin '' vīrus'') is a genus of RNA viruses in the family ''Rhabdoviridae'', order ''Mononegavirales''. Mammals, including humans, can serve as natural hosts. The genus ' ...

transmitted through wounds or bites from infected animals. The first symptoms are fever and pain near the infected site, which occur after a one to the three-month incubation period. Furious (more common type) rabies causes hyperactivity, hydrophobia, and aerophobia; death by cardio-respiratory arrest occurs within days. Paralytic rabies causes a slow progression from paralysis to coma to death. It can be prevented in dogs by vaccination and cleaning and disinfecting bite wounds (

post-exposure prophylaxis Post-exposure prophylaxis, also known as post-exposure prevention (PEP), is any preventive medical treatment started after exposure to a pathogen in order to prevent the infection from occurring. COVID-19 In 2021, the FDA has approved bamlanivi ...

). Rabies is undiagnosable before symptoms develop. It can be detected through tissue testing after symptoms develop.

Schistosomiasis

There are over 200 million cases of

. Approximately 85 percent of cases are in sub-Saharan Africa. The disease can be fatal by causing bladder cancer and

hematemesis Hematemesis is the vomiting of blood. It is always an important sign. It can be confused with hemoptysis (coughing up blood) or epistaxis (nosebleed), which are more common. The source is generally the upper gastrointestinal tract, typically abo ...

. ''

Schistosoma ''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed '' schistosomiasis'', which is considered by the World Health Organ ...

'' species have a complex life cycle that alternates between humans and freshwater snails. Infection occurs when the skin comes into contact with contaminated fresh water in which the snails that carry the parasite are living. Symptoms for schistosomiasis are not caused by the worms but by the body's reaction to the eggs. The eggs that do not pass out of the body can become lodged in the intestine or bladder, causing inflammation or scarring. Children who are repeatedly infected can develop anemia, malnutrition, and learning difficulties. The symptoms are usually

haematuria Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. “Gross hematuria” occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable w ...

, bladder obstruction,

renal failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...

bladder cancer Bladder cancer is any of several types of cancer arising from the tissues of the urinary bladder. Symptoms include blood in the urine, pain with urination, and low back pain. It is caused when epithelial cells that line the bladder become mali ...

, periportal fibrosis, bladder fibrosis, liver fibrosis, portal hypertension, cervical lesions,

ascites Ascites is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdominal size, increased weight, ab ...

, and

esophageal varices Esophageal varices are extremely dilated sub-mucosal veins in the lower third of the esophagus. They are most often a consequence of portal hypertension, commonly due to cirrhosis. People with esophageal varices have a strong tendency to develop ...

. Inexpensive

praziquantel Praziquantel (PZQ), sold under the brandname Biltricide among others, is a medication used to treat a number of types of helminthiasis, parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is us ...

can be used to treat individuals with schistosomiasis, but cannot prevent reinfection. The cost of prevention is US$0.32 per child per year.

Mass deworming Mass deworming, also called preventive chemotherapy, is the process of treating large numbers of people, particularly children, for helminthiasis (for example soil-transmitted helminths (STH)) and schistosomiasis in areas with a high prevalence ...

treatment with praziquantel, better access to safe water, sanitation, and health education can all be used to prevent schistosomiasis. Vaccines are under development. It can be diagnosed through a serological test, but it often produces false negatives.

Soil-transmitted helminthiasis

Adult ascaris worms being removed from the bile duct of a patient in South Africa

Soil-transmitted helminthiasis Soil-transmitted helminthiasis is a type of helminth infection (helminthiasis) caused by different species of roundworms. It is caused specifically by those worms which are transmitted through soil contaminated with faecal matter and are therefor ...

is the most prevalent neglected tropical disease. The three major worm species responsible for

are ''

Ascaris ''Ascaris'' is a genus of parasite, parasitic nematode worms known as the "small intestinal roundworms", which is a type of parasitic worm. One species, ''Ascaris lumbricoides'', affects humans and causes the disease ascariasis. Another species ...

'' (

roundworm The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a bro ...

s), ''

Trichuris ''Trichuris'', often referred to as whipworms (which typically refers to ''T. trichiura'' only in medicine, and to any other species in veterinary medicine), is a genus of parasitic worms from the roundworm family Trichuridae, which are helmin ...

'' (

whipworm ''Trichuris trichiura, Trichocephalus trichiuris'' or whipworm, is a parasitic roundworm (a type of helminth) that causes trichuriasis (a type of helminthiasis which is one of the neglected tropical diseases) when it infects a human large intes ...

), the hookworms ''

Necator americanus ''Necator americanus'' is a species of hookworm (a type of helminth) commonly known as the New World hookworm. Like other hookworms, it is a member of the phylum Nematoda. It is an obligatory parasitic nematode that lives in the small intestine ...

'' and ''

Ancylostoma duodenale ''Ancylostoma'' is a genus of nematodes that includes some species of hookworms. Species include: : ''Ancylostoma braziliense'', commonly infects cats, popularly known in Brazil as ''bicho-geográfico'' : ''Ancylostoma caninum'', commonly infec ...

'', and ''

Strongyloides stercoralis ''Strongyloides stercoralis'' is a human pathogenic parasitism, parasitic nematode, roundworm causing the disease strongyloidiasis. Its common name in the US is threadworm. In the UK and Australia, however, the term ''threadworm'' can also refe ...

''. There are 1.5 billion people currently infected. Soil-transmitted heminthiasis occurs in sub-Saharan Africa, the Americas, China, and east Asia. The mortality risk is very low. The most common symptoms are anemia,

stunted growth Stunted growth is a reduced growth rate in human development. It is a primary manifestation of malnutrition (or more precisely undernutrition) and recurrent infections, such as diarrhea and helminthiasis, in early childhood and even before birth, ...

, intestinal problems, lack of energy, and compromised physical and cognitive development. Infected children often fall behind in schooling. The severity of symptoms depends on the number of worms in the body. Parasitic worms are generally transmitted via exposure to infected human feces and soil that are spread in the environment, for example, due to

open defecation Open defecation is the human practice of defecating outdoors ("in the open") rather than into a toilet. People may choose fields, bushes, forests, ditches, streets, canals, or other open spaces for defecation. They do so either because they do ...

. The most common treatment is medicine. It can be prevented through hygienically prepared food and clean water, improved

sanitation Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation systems ...

, periodic deworming, and health education. The World Health Organization recommends

without prior diagnosis.

Taeniasis/cysticercosis

Cysticercosis Cysticercosis is a tissue infection caused by the cysticercus, young form of the Taenia solium, pork tapeworm. People may have few or no symptoms for years. In some cases, particularly in Asia, solid lumps of between one and two centimetres may ...

is a tapeworm larvae infection, while

taeniasis Taeniasis is an infection within the intestines by adult tapeworms belonging to the genus '' Taenia''. There are generally no or only mild symptoms. Symptoms may occasionally include weight loss or abdominal pain. Segments of tapeworm may be see ...

is infection with adult

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodar ...

s. Both are found in Asia, Africa, and Latin America, particularly on farms in which pigs are exposed to human excrement. Cysticercosis is the most common preventable cause of

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical ...

in the developing world. Cysticercosis occurs after ingestion of contaminated food, water, or soil. Cysts and lesions can cause headaches, Visual impairment, blindness, seizures, hydrocephalus, meningitis, and dementia. Neurocysticercosis, or the parasitic infection of the nervous system, can be fatal. Taeniasis is not fatal. It is usually contracted after eating undercooked contaminated pork. Taeniasis has mild symptoms, including abdominal pain, nausea, diarrhea, or constipation. Drugs are used to treat both diseases. Infection can be prevented through stricter meat-inspection standards, livestock confinement, improved hygiene and sanitation, health education, safe meat preparation, and identifying and treating human and pig carriers.

Trachoma

There are 21.4 million people infected with

, of whom 2.2 million are partially blind and 1.2 million are blind. It is found in Africa, Asia, Central, and South America, the Middle East, and Australia. The disease disproportionately affects women and children. The mortality risk is very low, although multiple re-infections eventually lead to blindness. The symptoms are internally scarred eyelids, followed by eyelids turning inward. Trachoma is caused by a micro-organism that spreads through eye discharges (on hands, cloth, etc.) and by "eye-seeking flies". It is treated with antibiotics. The only known prevention method is interpersonal hygiene.

Chromoblastomycosis and other deep mycoses

Scabies

Snakebite envenoming

Snakebite was added to the list in 2017, after years of criticism of the WHO by activists for not making it a priority. The Epidemiology of snakebites, greatest burden of snakebite morbidity is in India and Southeast Asia. Globally, there are an estimated 421,000 envenomings each year (about 1 in 4 snakebites) and 20,000 deaths, but snakebites often go unreported.

Effects for patients

Social effects

Social stigma

Several NTDs, such as

, cause severe deformities that result in social stigma. Stigma is considered to be the "hidden burden" of neglected tropical diseases and is not accounted for in measures such as disability-adjusted life years (DALYs). Other NTDs that carry heavy social stigma include

, Plague (disease), plague,

, leishmaniasis, and

. Lymphatic filariasis, for example, causes severe deformities that can result in denial of marriage and inability to work. Studies in Ghana and Sri Lanka have demonstrated that support groups for patients with lymphatic filariasis can increase participants' self-esteem, quality of life, and social relations through social support and providing practical advice on how to manage their illness. The social effects of neglected tropical diseases have been shown to affect men and women in different ways. Men are socially stigmatized in a way that detrimentally affects their economic prospects. Women are more likely to be affected in the areas of marriage and family.

Mental health

A 2012 review found that infection with a neglected tropical disease predisposes individuals to poor mental health. This is partially due to the social stigma that surrounds NTDs, but is also likely caused by the subsequent lack of access to health and social services. Overall, being a member of the infected community was found to cut individuals off from multiple aspects of society via civic rights, educational opportunities, and employment. A high prevalence of post-traumatic stress disorder (PTSD) and depression was found in those affected with snakebite survivors. There is a need for more research be directed to understanding the psychological aspects of neglected tropical diseases in order to fully untangle their co-effects and on how they can be dealt with better in health systems in countries where mental health professionals are scarce.

Gender

NTDs disproportionately affect women and children. There is also the added risk of hookworm infection during pregnancy and the potential to transfer diseases such as Chagas during pregnancy. A study in Uganda found that women were more easily able to obtain treatment because they had fewer occupational responsibilities than men and were more trusting of treatment, but ignorance of the effects of medicines on pregnant women prevented adequate care. The paper concludes that gender should be considered when designing treatment programs in Uganda. Additionally, women often bear a heavier social stigma in relation to the pressure to marry.

Economic effects

The cost of treatment of some of these diseases, such as Buruli ulcer, can amount to over twice the yearly income of an average household in the lowest income quartile, while for the highest income quartile, the burden is slightly less than the average household income. These enormous financial costs often cause deferral of treatment and financial ruin, but there is inequality between the wealthy and poor in terms of economic burden. These diseases also cost the government in terms of health care and lost worker productivity through morbidity and shortened life spans. In Kenya, for example, deworming is estimated to increase average adult income by 40 percent, which is a benefit-to-cost ratio of 100. Each untreated case of Trachoma is estimated to cost US$118 in lost productivity. Each case of schistosomiasis causes a loss of 45.4 days of work per year. Most of the diseases cost the economies of various developing countries millions of dollars. Large-scale prevention campaigns are predicted to increase agricultural output and education levels. The low cost of treatment for NTDs can be attributed to the large scale of the programs, free provision of drugs by pharmaceutical companies, delivery modes of drugs, and the unpaid volunteers who distribute the drugs. The economic burden of NTDs is undervalued and therefore the corresponding economic effect and cost-effectiveness of a decreased prevalence of NTDs is underestimated. The investment return on measures to control neglected tropical diseases is estimated to be between 14 and 30 percent, depending on the disease and region.

Health effects

Coinfection

Coinfection is a major concern with neglected tropical diseases, making NTDs more damaging than their Mortality rate, mortality rates might portray. Because the factors that support neglected tropical diseases (poverty, inadequate healthcare, inadequate sanitation practices, etc.) support all NTDs, they are often found in overlapping distributions. Helminthiasis, Helminth infections, as the most common infection of humans, are often found to be in multi-infection systems. For example, in Brazil, low socioeconomic status contributes to overcrowded housing. In these same areas, connection by ''

'' and ''Schistosoma mansoni'' is common. The effect of each worm weakens the immune system of those infected, making infection from the other easier and more severe. For this reason, coinfection carries a higher risk of mortality. NTDs may also play a role in infection with other diseases, such as

, and

. The ability of helminths to manipulate the immune system may create a physiological environment that could exacerbate the progression of

. Some evidence from Senegal, Malawi, and Thailand has shown that helminth infections raise the risk of malarial infection.

Prevention, treatment and eradication

On the Road to Eliminating Neglected Tropical Diseases in Cote d'Ivoire (29464931444)

Prevention and eradication are important because "of the appalling stigma, disfigurement, blindness, and disabilities caused by NTDs." The possibility of eliminating or eradicating

, African sleeping sickness, sleeping sickness, visceral leishmaniasis, and canine

within the next ten years was the principal aim of the London Declaration on Neglected Tropical Diseases, which is a collaborative effort involving the WHO, the World Bank, the Bill & Melinda Gates Foundation, the world's 13 leading pharmaceutical companies, and government representatives from the US, UK, United Arab Emirates, Bangladesh, Brazil, Mozambique, and Tanzania. It was launched in January 2012. While the current era has had a noticeable uptick in biological research into neglected tropical diseases, prevention may be supplemented by social and development outreach. Spiegal and his coauthors advocated for this to take the form of a "social offset". Social offset entails the delegation of some of the funding for biotechnological research to social programs. The attempts to alleviate some of the surrounding factors (such as poverty, poor sanitation, overcrowding, poor healthcare, etc.) that greatly exacerbate the conditions brought on by neglected tropical diseases. Projects such as these also strengthen the goal of sustained eliminations rather than quickly addressing symptoms.

Policy initiatives

There are many prevention and eradication campaigns funded, for example, by the World Health Organization, US Agency for International Development, Bill and Melinda Gates Foundation, and UK Department for International Development. Sustainable Development Goal 3 has this target to eradicate NTDs: "By 2030, end the epidemics of AIDS, tuberculosis, malaria and neglected tropical diseases and combat hepatitis, Waterborne diseases, water-borne diseases and other Infection, communicable diseases."United Nations (2017) Resolution adopted by the General Assembly on 6 July 2017, :File:A RES 71 313 E.pdf, Work of the Statistical Commission pertaining to the 2030 Agenda for Sustainable Development
A/RES/71/313

WHO Roadmap of 2012

In 2012, WHO published an NTD "roadmap", which contained milestones for 2015 and 2020 and specified targets for eradication, elimination, and intensified control of the different NTDs. For example: * NTDs planned to be eradicated: dracunculiasis (by the year 2015), Yaws, endemic treponematoses (yaws) (by 2020) * NTDs planned to be eliminated globally by 2020: blinding trachoma,

, human African trypanosomiasis, and lymphatic filariasis * NTDs planned to be eliminated in certain regions: rabies (by 2015 in Latin America, by 2020 in Southeast Asia and the western Pacific),

(transmission through blood transfusion by 2015, intra-domiciliary transmission by 2020 in the Americas), visceral leishmaniasis (by 2020 in the Indian subcontinent), onchocerciasis (by 2015 in Latin America), and schistosomiasis (by 2015 in the eastern Mediterranean region, the Caribbean, Indonesia, and the Mekong River basin, by 2020 in the Americas and western Pacific) * NTDs planned to be eliminated in certain countries: human African trypanosomiasis (by 2015 in 80 percent of areas in which it occurs), onchocerciasis (by 2015 in Yemen, by 2020 in selected countries in Africa), and schistosomiasis (by 2020 in selected countries in Africa) * Intensified control with specific targets for 2015 and 2020 are provided for these NTDs: dengue, buruli ulcer, cutaneous leishmaniasis,

and

/hydatidosis, foodborne trematode infections, and soil-transmitted helminthiases

Others

The U.S. Food and Drug Administration priority review voucher is an incentive for companies to invest in new drugs and vaccines for tropical diseases. A provision of the Food and Drug Administration Amendments Act (HR 3580) awards a transferable "priority review voucher" to any company that obtains approval for a treatment for one of the listed diseases. The voucher can later be used to accelerate the review of an unrelated drug. This program is for all tropical diseases and includes medicines for malaria and tuberculosis. The first voucher given was for Coartem, a malaria treatment. It does not use or define the term "neglected", though most of the diseases listed are often included on lists of neglected diseases. The prize was proposed by Duke University faculty Henry Grabowski, Jeffrey Moe, and David Ridley in their 2006 ''Health Affairs'' paper "Developing Drugs for Developing Countries". In 2007, United States Senators Sam Brownback (R-KS) and Sherrod Brown (D-OH) sponsored an amendment to the Food and Drug Administration Amendments Act of 2007. President George W. Bush signed the bill in September 2007.

Deworming treatment

Deworming treatments in infected children may have some nutritional benefit, as worms are often partially responsible for malnutrition. However, in areas where these infections are common, there is strong evidence that

campaigns do not have a positive effect on children's average nutritional status, levels of blood Hemoglobin, haemoglobin, cognitive abilities, performance at school, or survival. To achieve health gains in the longer term, improvements in

and hygiene behaviours are also required, together with deworming treatments. The effect of mass deworming on school attendance is disputed. It has been argued that mass deworming has a positive effect on school attendance. The long-term benefits of deworming include a decrease in school absenteeism by 25 percent and an increase in adult earnings by 20 percent. A systematic review, however, found that there is little or no difference in attendance in children who receive mass deworming compared to children who did not. One study found that boys were enrolled in primary school for more years than boys who were in schools that did not offer such programs. Girls in the same study were about a quarter more likely to attend secondary school if they received treatment. Both groups went on to participate in more skilled sectors of the labor market. The economic growth generated from school programs such as this may balance out the actual expenses of the program. However, the results of this study are disputed (i.a. due to a high risk of bias in the study), and the positive long-term outcomes of mass deworming remain unclear.

Integration of treatment

Inclusion of NTDs into initiatives for

, and

, as well as integration of NTD treatment programs, may have advantages given the strong link between these diseases and NTDs. Some neglected tropical diseases share common vectors (sandflies, black flies, and mosquitos). Both medicinal and vector control efforts may be combined. A four-drug rapid-impact package has been proposed for widespread proliferation. Administration may be made more efficient by targeting multiple diseases at once, rather than separating treatment and adding work to community workers. This package is estimated to cost US$0.40 per patient. When compared to stand-alone treatment, the savings are estimated to be 26–47%. While more research must be done in order to understand how NTDs and other diseases interact in both the vector and the human stages, safety assessments have so far produced positive results. Many neglected tropical diseases and other prevalent diseases share common vectors, creating another opportunity for treatment and control integration. One such example of this is malaria and lymphatic filariasis. Both diseases are transmitted by the same or related mosquito vectors. Vector control, through the distribution of insecticide-treated nets, reduces human contact with a wide variety of disease vectors. Integrated vector control may also alleviate pressure on mass drug administration, especially with respect to rapidly evolving drug resistance. Combining vector control and mass drug administration deemphasizes both, making each less susceptible to resistance evolution.

Integration with WASH programs

Water, sanitation, and hygiene (WASH) interventions are essential in preventing many NTDs, such as

. Mass drug administrations alone will not protect people from re-infection. A more holistic and integrated approach to NTDs and WASH efforts will benefit both sectors along with the communities they are aiming to serve. This is especially true in areas that are endemic with more than one NTD. In August 2015, the World Health Organization unveiled a global strategy and action plan to integrate WASH with other public health interventions in order to accelerate the elimination of NTDs. The plan aims to intensify control or eliminate certain NTDs in specific regions by 2020 and refers to the NTD "roadmap" milestones from 2012 that include, for example, eradication of dracunculiasis by 2015 and of yaws by 2020, elimination of trachoma and lymphatic filariasis as public health problems by 2020, and intensified control of dengue, schistosomiasis, and soil-transmitted helminthiases.World Health Organization (WHO) (2015)
Water Sanitation and Hygiene for accelerating and sustaining progress on Neglected Tropical Diseases. A global strategy 2015–2020
. Geneva, Switzerland, p. 26 Closer collaboration between WASH and NTD programmes can lead to synergies. They can be achieved through collaborative planning, delivery, and evaluation of programmes, strengthening and sharing of evidence, and using monitoring tools to improve the equity of health services. Reasons why WASH plays an important role in NTD prevention and patient care include: * NTDs affect more than one billion people in 149 countries. They occur mainly in regions with a lack of basic sanitation. About 2.4 billion people worldwide do not have adequate sanitation facilities. 663 million do not have access to Improved water source, improved drinking water sources. * One leading cause of preventable blindness is

. The bacterial infection is transmitted through contact with eye-seeking flies, fingers, and fomites. Prevention components are facial cleanliness, which requires water for face washing, and environmental improvement, which includes safe disposal of excreta to reduce fly populations. * Improved sanitation prevents Soil-transmitted helminthiasis, soil-transmitted helminthiases. It impedes fecal pathogens such as intestinal worm eggs from contaminating the environment and infecting people through contaminated food, water, dirty hands, and direct skin contact with the soil. * Improved sanitation and water management can contribute to reducing the proliferation of mosquitoes that transmit diseases, such as

, and chikungunya. Breeding of the ''Culex'' mosquito which transmits filarial parasites is facilitated through poorly constructed latrines. Breeding of the ''

'' and ''Aedes albopictus'' mosquitoes which transmit dengue and chikungunya can be prevented through safe storage of water. * Feces and urine that contain worm eggs can contaminate surface water and lead to transmission of

. This can be prevented through improved sanitation. Not only human but also animal (cow, buffalo) urine or feces can transmit some schistosome species. Therefore, it is important to protect freshwater from animals and animal waste. * Treatment of many NTDs require clean water and hygienic conditions for healthcare facilities and households. For Guinea Worm Disease, guinea worm,

, or cutaneous leishmaniasis, wound management is needed to speed up healing and reduce disability. Lymphatic filariasis causes chronic disabilities. People who have this disease need to maintain rigorous personal hygiene with water and soap to prevent secondary infections. * NTDs that lead to permanent Disability, disabilities make tasks such as carrying water long distances or accessing toilets difficult. However, people affected by these diseases often face Social stigma, stigma and can be excluded from accessing water and sanitation facilities. This increases their risk of poverty and severe illness. Clean water and soap are essential for these groups to maintain personal hygiene and dignity. Therefore, additional efforts to reduce stigma and exclusion are needed. In this manner, WASH can improve the quality of life of people affected by NTDs. * In a meta-analysis, safe water was associated with significantly reduced odds of ''

'' infection, and adequate sanitation was associated with significantly lower odds of infection with both Schistosoma mansoni, ''S. mansoni'' and ''Schistosoma haematobium, S. haematobium''. * A systematic review and meta-analysis showed that better hygiene in children is associated with lower odds of trachoma. Access to sanitation was associated with 15 percent lower odds of active

and 33 percent lower odds of ''Chlamydia trachomatis, C. trachomatis'' infection of the eyes. * Another systematic review and meta-analysis found a correlation between WASH access and practices and lower odds of

infections by 33 to 77 percent. Persons who Hand washing, washed their hands after Defecation, defecating were less than half as likely to be infected as those who did not. Traditionally, preventive chemotherapy is used as a measure of control, although this measure does not stop the transmission cycle and cannot prevent reinfection. In contrast, improved sanitation can.

Pharmaceutical market

Biotechnology companies in the developing world have targeted neglected tropical diseases due to a need to improve global health. Mass drug administration is considered a possible method for eradication, especially for lymphatic filariasis, onchocerciasis, and trachoma, although drug resistance is a potential problem. According to Fenwick, Pfizer donated 70 million doses of drugs in 2011 to eliminate trachoma through the International Trachoma Initiative. Merck & Co., Merck has helped The African Programme for the Control of Onchocerciasis (APOC) and Oncho Elimination Programme for the Americas to greatly diminish the effect of onchocerciasis by donating

. Merck KGaA pledged to give 200 million tablets of

over 10 years, the only cure for

. GlaxoSmithKline has donated two billion tablets of medicine for lymphatic filariasis and pledged 400 million deworming tablets per year for five years in 2010. Johnson & Johnson has pledged 200 million deworming tablets per year. Novartis has pledged leprosy treatment, and Eisai (company), EISAI pledged two billion tablets to help treat lymphatic filariasis.

NGO initiatives

Non-governmental organizations that focus exclusively on NTDs include the Schistosomiasis Control Initiative, Deworm the World, and the END Fund. Despite under-funding, many neglected diseases are cost-effective to treat and prevent. The cost of treating a child for infection of soil-transmitted helminths and schistosomes (some of the main causes of neglected diseases) is less than US$0.50 per year when administered as part of school-based mass deworming by Deworm the World. This programme is recommended by Giving What We Can and the Copenhagen Consensus Centre as one of the most efficient and cost-effective solutions. The efforts of the Schistosomiasis Control Initiative to combat neglected diseases include the use of rapid-impact packages: supplying schools with packages including four or five drugs, and training teachers in how to administer them. Health Action International based in Amsterdam worked with the WHO to get snakebite envenoming on the list of neglected tropical diseases.

Public-private initiatives

An alternative to the profit-driven drug development model emerged in 2000 to address the needs of these neglected patients. Product development partnerships (PDPs) aim at implementing and accelerating the research and development (R&D) of safe and effective health tools (diagnostics, vaccines, drugs) to combat neglected diseases. Drugs for Neglected Disease initiative (DNDi) is one of these PDPs that has already developed new treatments for NTDs. The Sabin Vaccine Institute, founded in 1993, works to address the issues of vaccine-preventable diseases as well as NTDs. They run three main programs: Sabin Vaccine Development, Global Network for Neglected Tropical Diseases, and Vaccine Advocacy and Education. Their product development partnership affiliates them with the Texas Children's Hospital as well as the Baylor College of Medicine. Their major campaign, End7, aims to end seven of the most common NTDs (elephantiasis, Onchocerciasis, river blindness, Schistosomiasis, snail fever,

, helminthiasis, roundworm, Trichuriasis, whipworm, and Hookworm infection, hookworm) by 2020. Through End7, college campuses undertake fundraising and educational initiatives for the broader goals of the campaign. WIPO Re:Search was established in 2011 by the World Intellectual Property Organization in collaboration with BIO Ventures for Global Health (BVGH) and with the active participation of leading pharmaceutical companies and other private and public sector research organizations. It allows organizations to share their intellectual property, compounds, expertise, facilities, and know-how royalty-free with qualified researchers worldwide working on new solutions for NTDs, malaria, and tuberculosis. In 2013, the Government of Japan, five Japanese pharmaceutical companies, the Bill and Melinda Gates Foundation, and the UNDP established a new public–private partnership, the Global Health Innovative Technology Fund. They pledged over US$100 million to the fund over five years, to be awarded as grants to R&D partnerships across sectors in Japan and elsewhere, working to develop new drugs and vaccines for 17 neglected diseases, in addition to HIV, malaria, and tuberculosis."Japan in pioneering partnership to fund global health research", by Andrew Jack, ''Financial Times'', 30 May 2013 Affordability of the resulting drugs and vaccines is one of the key criteria for grant awards.

Others

An open-access journal dedicated to neglected tropical diseases called ''PLoS Neglected Tropical Diseases'' first began publication in 2007. One of the first large-scale initiatives to address NTDs came from a collaboration between Kenneth S. Warren, Kenneth Warren and the Rockefeller Foundation. Ken Warren is regarded as a pioneer in neglected tropical disease research. The Great Neglected Tropical Diseases Network was a consortium of scientists from all over the world, hand-picked by Warren, working to expand the research base in neglected diseases. Many of the scientists that he recruited had not been involved in NTD research before. The network ran from 1978 to 1988. Warren's vision was to establish units within biological labs across the world, dedicated to Neglected tropical disease research and development, R&D. By forming a critical mass of scientists in NTD research, he hoped to attract new students into the field. The interdisciplinary group met annually to update the community on research progress. Much of the work done by this group focused on understanding the mechanisms behind the infection. At these informally structured meetings, research partnerships were formed. Warren himself encouraged these partnerships, especially if they bridged the divide between developed and developing nations. Through the Great Neglected Tropical Disease Network, a great number of scientists were brought into the field of parasitology.

Epidemiology

The distribution of neglected tropical disease disproportionally affects about one billion of the world's poorest populations, causing mortality, disability, and morbidity. Lack of funding, resources, and attention can result in treatable and preventable diseases causing death. Factors like political dynamics, poverty, and geographical conditions can make the delivery of NTD control programs difficult. Intersectional collaboration of poverty reduction policies and neglected tropical diseases creates cross-sector approaches to simultaneously address these issues. The six most common NTDs include soil-transmitted helminths (STHs)—specifically roundworms (''Ascaris lumbricoides''), whipworm (''Trichuris trichiura''), and hookworms (''Necator americanus'' and ''Ancylostoma duodenale'')—schistosomiasis, trachoma, and lymphatic filariasis (LF). These diseases affect one-sixth of the world's population, with 90 percent of the disease burden occurring in sub-Saharan Africa. Information on the frequency of neglected tropical diseases is of low quality. It is currently difficult to summarize all of the information on this family of diseases. One effort to do so is the Global Burden of Disease framework. It aims to create a standardized method of measurement. The principle components of the approach involve 1) the measuring of premature mortality as well as disability, 2) the standardized usage of DALYs (disability-adjusted life years), and 3) widespread inclusion of diseases and injury causes with the estimation of missing data. However, the DALY has been criticized as a "systematic undervaluation" of disease burden. King asserts that DALY emphasizes the individual too much while ignoring the effects of the ecology of the disease. In order for the measure to become more valid, it may have to take the context of poverty more into account. King also emphasizes that DALYs may not capture the non-linear effects of poverty on the cost-utility analysis of disease control. The Socio-Demographic Index (SDI) and Healthy Life Expectancy (HALE) are other summary measures that can be used to take into account other factors. HALE is a metric that weights years lived and health loss before death to provide a summary of population health. SDI is a measurement that includes lag-distributed income per capita, average education, and fertility rate. Socioeconomic factors greatly influence the distribution of neglected tropical diseases, and not addressing these factors in models and measurements can lead to ineffective public health policy.

Research and development

NTD interventions include programs to address environmental and social determinants of health (e.g., vector control, water quality, sanitation) as well as programs offering

for disease prevention and treatment. Drug treatments existReddy M, Gill SS, Kalkar SR, Wu W, Anderson PJ, Rochon PA. Oral drug therapy for multiple neglected tropical diseases: a systematic review. ''JAMA'' 2007 Oct 24;298(16):1911-1924. to confront many of the NTDs and represent some of the world's essential medicines.Trouiller P, Olliaro P, Torreele E, Orbinski J, Laing R, Ford N. Drug development for neglected diseases: a deficient market and a public-health policy failure. ''Lancet'' 2002 Jun 22;359(9324):2188-2194.Cohen J, Dibner MS, Wilson A. Development of and access to products for neglected diseases. ''PLoS One'' 2010 May 12;5(5):e10610. Despite significant health and economic improvements using available medicines,Conteh L, Engels T, Molyneux DH. Socioeconomic aspects of neglected tropical diseases. ''Lancet'' 2010 Jan 16;375(9710):239-247.Chu BK, Hooper PJ, Bradley MH, McFarland DA, Ottesen EA. The economic benefits resulting from the first 8 years of the Global Programme to Eliminate Lymphatic Filariasis (2000–2007). PLoS Negl Trop Dis. 2010 Jun 1;4(6):e708.Merck Mectizan Drug Donation Program http://www.mectizan.org/Villa S, Compagni A, Reich MR. Orphan drug legislation: lessons for neglected tropical diseases. ''Int J Health Plann Manage'' 2009 Jan-Mar;24(1):27-42. the low number of new compounds being researched and developed for NTDs is an ongoing and significant challenge.Chirac P, Torreele E. Global framework on essential health R&D. Lancet. 2006 May 13;367(9522):1560-1. The dearth of candidates in the pharmaceutical company drug pipelines is primarily attributed to the high costs of drug development and the fact that NTDs are concentrated among the world's poor.Trouiller P, Torreele E, Olliaro P, White N, Foster S, Wirth D, et al. Drugs for neglected diseases: a failure of the market and a public health failure? ''Trop Med Int Health'' 2001 Nov;6(11):945-951. Other disincentives to investment include weak existing infrastructure for distribution and sales as well as concerns regarding intellectual property protection. However, the major stakeholders in NTD drug development—governments, foundations, pharmaceutical companies, academia, and Non-governmental organization, NGOs—are involved in activities to help address the research and development shortfall and meet the many challenges presented by neglected tropical diseases.Liese B, Rosenberg M, Schratz A. Programmes, partnerships, and governance for elimination and control of neglected tropical diseases. ''Lancet'' 2010 Jan 2;375(9708):67-76. Initiatives include public-private partnerships, global R&D capacity building, priority vouchers to speed drug approval processes, open source scientific collaborations, and harmonization of global governance structures concerning NTDs. The diseases considered neglected tropical diseases vary. Some researchers no longer consider

, HIV/AIDS, HIV, and

to be neglected due to the amount of public attention and increased funding they have received. Outside "The Big Three", the seven most prevalent neglected tropical diseases in order of their global prevalence are

, hookworm infection,

, and

. These seven are among a larger list of thirteen major NTDs:

, leishmaniasis,

, human African trypanosomiasis (sleeping sickness),

, and

Deficient market

In their 2002 review of the U.S. Food and Drug Administration (FDA) databases and the European Medicines Agency, European Agency for the Evaluation of Medicinal Products, Troullier ''et al'' found that 16 out of 1393 new chemical entities were approved for NTDs between 1975 and 1999 (~1%). Cohen ''et al'' revisited the data and using the same methodology found 32 new chemical entities during the time period. In a second analysis using an expanded list of NTDs based on the G-FINDER survey,G-FINDER Database http://www.georgeinstitute.org/about-us/media-centre/g-finder-database-open-public the number was slightly higher, with 46 new drugs and vaccines approved (~3% of the total including HIV drugs). Between 2000 and 2009, there has been some increase with an additional 26 newly approved drugs and vaccines for NTDs. A number of factors are recognized as contributing to the low number. The barrier most reported is the high cost of drug development. Estimates are that pharmaceutical companies' development costs to approval fall between $500 million and $2 billion.Adams CP, Brantner VV. Estimating the cost of new drug development: is it really 802 million dollars? Health Aff (Millwood). 2006 Mar-Apr;25(2):420-8. DiMasi, Hansen, and Grabowski calculated an average of $802 million in the year 2000 dollars.DiMasi JA, Hansen RW, Grabowski HG. The price of innovation: new estimates of drug development costs. J Health Econ. 2003 Mar;22(2):151-85. Furthermore, the time that drugs are approved for use averages seven years out of the twenty years on patent, meaning a tendency for the market to focus on diseases of developed nations where high prices can be used to recoup research and development costs, and subsidize failed R&D efforts. In short, NTD research and development is considered a high investment risk is given that NTDs predominantly affect the poor in low- and middle-income countries.Bethony JM, Cole RN, Guo X, Kamhawi S, Lightowlers MW, Loukas A, et al. Vaccines to combat the neglected tropical diseases. ''Immunol Rev'' 2011 Jan;239(1):237-270. Additional barriers include drug safety regulatory requirements, intellectual property protection problems, and poor infrastructure for distribution and sales. Although drug companies have not invested heavily in NTDs, in several cases, rather than focus on profits, some have decided to donate key drugs to address NTDs. For example, Merck has had a program since the mid-1980s to donate ivermectin (Mectizan) indefinitely to support the global fight against onchocerciasis. GlaxoSmithKline and several other large pharmaceutical companies have donation programs as well. Drug donation, however, does not ameliorate the deficiency of new chemical entities being researched and developed. This is especially of concern with reports of emerging resistance among existing drugs.Tchuem Tchuente LA. Control of soil-transmitted helminths in sub-Saharan Africa: Diagnosis, drug efficacy concerns and challenges. ''Acta Trop'' 2010 Jul 21.Smits HL. Prospects for the control of neglected tropical diseases by mass drug administration. ''Expert Rev Anti Infect Ther'' 2009 Feb;7(1):37-56.

Policy initiatives

Public-private partnerships

Governments, foundations, the non-profit sector, and the private sector have found new connections to help address market deficiencies by providing funding support and spreading both the costs and risks of NTD research and development. The proliferation of public–private partnerships (PPPs) has been recognized as a key innovation in the past decade, helping to unlock existing and new resources. Major PPPs for NTDs include: the Sabin Vaccine Institute, Norvartis Vaccines Institute for Global Health, MSD Wellcome Trust Hilleman Laboratories, Infectious Diseases Research Institute, Institut Pasteur and INSERM, WIPO Re:Search, and the International Vaccine Institute. Likewise, a number of new academic drug development centers have been created in recent years drawing in industry partners. Support for these centers is frequently traced to the Bill and Melinda Gates Foundation, the Sandler Foundation, and the Wellcome Trust.Renslo AR, McKerrow JH. Drug discovery and development for neglected parasitic diseases. ''Nat Chem Biol'' 2006 Dec;2(12):701-710.

R&D capacity building in middle-income countries

Growing NTD research and development capacity in middle-income countries is an area of policy interest. A 2009 study of biotechnology companies in India, China, Brazil, and South Africa revealed 62 NTD products in development and on the market out of approximately 500 products offered (~14%). When products to fight HIV, malaria, and TB were included in the analysis, the number increased to 123 products, approximately 25% of the total products offered. Researchers have argued that, unlike most multinationals, small and mid-sized "Global South" companies see significant business opportunities in the development of NTD-related diagnostics, biologics, pharmaceuticals, and services.Frew SE, Liu VY, Singer PA. A business plan to help the 'global South' in its fight against neglected diseases. ''Health Aff'' (Millwood) 2009 Nov-Dec;28(6):1760-1773. Potential actions to improve and expand this R&D capacity have been recommended, including expansion of human capital, increased private investment, knowledge and patent sharing, infrastructure building for business incubation, and innovation support.

Innovation prizes and grants

Competitive innovation prizes have been used to spur development in a range of fields such as aerospace engineering, clean technology, and genomics. The X-Prize Foundation is launching a competition for high-speed, point-of-care diagnostics for tuberculosis. A more widely defined annual "Global Health EnterPrize" for neglected tropical diseases has been proposed to reward health innovators, particularly those based in countries where NTDs represent a serious health burden. The Bill & Melinda Gates Foundation offers the Grand Challenges Explorations Opportunities on a rolling basis. This grant program allows individuals from any organization or background to apply to address priority global health issues. Each project award is $100,000 dollars and is drawn from a Foundation funding pool of $100 million. Awardees have tended to offer research projects on topics that are highly speculative but offer potentially game-changing breakthroughs in global health.

FDA priority review vouchers (PRV)

In 2006, Ridley ''et al'' recommended the development of a priority review voucher (PRV) in the journal ''Health Affairs''. It gained interest from Senator Sam Brownback of Kansas, who championed its introduction in the Food and Drug Administration Amendments Act of 2007, FDA Amendments Act of 2007. Under the enacted law, FDA approval of a non-NTD drug can be accelerated through the drug review process if paired with a drug that addresses an NTD. The potential economic benefit to a pharmaceutical company is estimated to be potentially as high as $300 million per drug. Three drugs have earned NTD PRVs to date (December 2014): Coartem (by Novartis, for malaria); bedaquiline (by Janssen, for TB); and miltefosine (by Knight, for leishmaniasis). However, the success of the PRV system is now under much scrutiny, given that Knight benefitted by $125 million from the sale of a PRV earned from a drug (miltefosine) that was largely researched and developed by the WHO. Médecins Sans Frontières are now pressuring Knight to guarantee to supply miltefosine at cost price, thus far without success. The PRV isn't limited to the pairing of drugs within a single company as it can be transferred between companies. Companies with NTD drug candidates in their pipelines but without a blockbuster drug are able to sell their vouchers, producing financial returns. In the EU, similar priority review incentives are now under consideration to increase the speed of regulatory pricing and reimbursement decisions. However, PRVs have been criticized as being open to manipulation and possibly encouraging errors through too rapid regulatory decision-making.Kesselheim AS. Drug development for neglected diseases – the trouble with FDA review vouchers. ''N Engl J Med'' 2008 Nov 6;359(19):1981-1983.

Open source collaboration initiatives

Several companies and scientific organizations are participating in open-source initiatives to share drug data and patent information over the web, and facilitate virtual collaboration on NTD research. One rich area to explore is the wealth of genomic data resulting from the sequencing of parasite genomes. These data offer opportunities for the exploration of new therapeutic products using computational and open source collaboration methods for drug discovery.Kar S. Opinion: Open innovation: an answer for neglected diseases. ''Future Med Chem'' 2010 Sep;2(9):1411-5.Ortí L, Carbajo RJ, Pieper U, Eswar N, Maurer SM, Rai AK, Taylor G, Todd MH, Pineda-Lucena A, Sali A, Marti-Renom MA. A kernel for open source drug discovery in tropical diseases. ''PLoS Negl Trop Dis'' 2009;3(4):e418. The Tropical Disease Initiative, for example, has used large amounts of computing power to generate the protein structures for ten parasite genomes. An open-source drug bank was matched algorithmically to determine compounds with protein interaction activity, and two candidates were identified. In general, such methods may hold important opportunities for off-label use of existing approved drugs.

History

In 1977, Kenneth S. Warren, an American researcher, invented the concept of what is now "neglected tropical diseases".

References

External links

WHO – Control of neglected tropical disease

''PLOS Neglected Tropical Diseases''

United Nations World Health Organization

India’s neglected tropical diseases

Neglected tropical disease targets must include morbidity

Global health policy and neglected tropical diseases: Then, now, and in the years to come
{{Portal bar, Medicine Human diseases and disorders Infectious diseases Tropical diseases Sanitation

Reasons for neglect

Stigma

Economic incentives

Developed nations

List of diseases

Buruli ulcer

Chagas disease

Dengue and chikungunya

Dracunculiasis

Echinococcosis

Yaws

Foodborne trematodiases

Human African trypanosomiasis

Leishmaniasis

Leprosy

Lymphatic filariasis

Onchocerciasis

Rabies

Schistosomiasis

Soil-transmitted helminthiasis

Taeniasis/cysticercosis

Trachoma

Chromoblastomycosis and other deep mycoses

Scabies

Snakebite envenoming

Effects for patients

Social effects

Social stigma

Mental health

Gender

Economic effects

Health effects

Coinfection

Prevention, treatment and eradication

Policy initiatives

WHO Roadmap of 2012

Others

Deworming treatment

Integration of treatment

Integration with WASH programs

Pharmaceutical market

NGO initiatives

Public-private initiatives

Others

Epidemiology

Research and development

Deficient market

Policy initiatives

Public-private partnerships

R&D capacity building in middle-income countries

Innovation prizes and grants

FDA priority review vouchers (PRV)

Open source collaboration initiatives

History

See also

References

External links