The discipline of medical entomology, or public health entomology, and also ''veterinary entomology'' is focused upon

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s and

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s that impact human health. Veterinary entomology is included in this category, because many animal diseases can "jump species" and become a human health threat, for example, bovine encephalitis. Medical entomology also includes scientific research on the behavior, ecology, and

epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evi ...

of arthropod disease vectors, and involves a tremendous outreach to the public, including local and state officials and other stake holders in the interest of public safety. Public health entomology has seen a huge surge in interest since 2005, due to the resurgence of the bed bug, ''Cimex lectularius.''

Insects of medical importance

There are many insects (and other arthropods) that affect human health. These arthropods include

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to arou ...

, Thysanoptera, Phthiraptera, and

Siphonaptera Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, ar ...

. They can parasitize, bite, sting, cause allergic reactions, and/or vector disease to humans. insects are good for it can be impossible to know the full impact that insects and other arthropods have on human health. Medical entomologists worldwide are working to combat the known effects in order to improve public health.

Personal pests

Personal pests such as

lice Louse ( : lice) is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a resul ...

, fleas,

bedbugs Bed bugs are insects from the genus ''Cimex'' that feed on blood, usually at night. Their bites can result in a number of health impacts including skin rashes, psychological effects, and allergic symptoms. Bed bug bites may lead to skin chang ...

ticks Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...

, scabies mites, may vector pathogens. They are

hematophagous Hematophagy (sometimes spelled haematophagy or hematophagia) is the practice by certain animals of feeding on blood (from the Greek words αἷμα ' "blood" and φαγεῖν ' "to eat"). Since blood is a fluid tissue rich in nutritious p ...

, meaning they feed on the blood of their host. Nearly all personal pests can be transmitted to an uninfected host with prolonged exposure to an infected host. Lice, fleas, bedbugs, and ticks are known as

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 ha ...

. Ectoparasites live on the skin of their host. They have adaptations that allow them to access the nutrients inside of the host, such as methods to penetrate skin, insert digestive enzymes and a

gut microbiome Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the ...

that can digest the nutrients received from the host. While these ectoparasites feed, the transfer of fluids may transmit diseases such as typhus, plague, and Lyme disease. It is also suspected that bedbugs may also be vectors of hepatitis B. Scabies mites cannot be classified as ectoparasites. The mite that causes scabies, ''

Sarcoptes scabiei ''Sarcoptes scabiei'' or the itch mite is a parasitic mite that burrows into skin and causes scabies. The mite is found in all parts of the world. Humans are not the only mammals that can become infected. Other mammals, such as wild and domes ...

'' also known as the itch mite, burrows into the skin of its host making it an endoparasite. The act of ''S. scabiei'' living in the skin and the allergic response to the parasite is the condition known as

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 ski ...

Housefly

The

housefly The housefly (''Musca domestica'') is a fly of the suborder Cyclorrhapha. It is believed to have evolved in the Cenozoic Era, possibly in the Middle East, and has spread all over the world as a commensal of humans. It is the most common fl ...

is a very common and cosmopolitan species which transmits diseases to man. The organisms of both amoebic and bacillary dysenteries are picked up by flies from the faeces of infected people and transferred to clean food either on the fly's hairs or by the fly vomiting during feeding.

Typhoid Typhoid fever, also known as typhoid, is a disease caused by ''Salmonella'' serotype Typhi bacteria. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often there is a gradual onset of a high fever over several d ...

germs may be deposited on food with the fly's faeces. The house fly cause the spread of

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 ulc ...

germs by carrying them from a yaws ulcer to an ordinary sore. Houseflies also transmit

poliomyelitis Poliomyelitis, commonly shortened to polio, is an infectious disease caused by the poliovirus. Approximately 70% of cases are asymptomatic; mild symptoms which can occur include sore throat and fever; in a proportion of cases more severe sym ...

by carrying the virus from infected faeces to food or drink.

Cholera Cholera is an infection of the small intestine by some strains of the bacterium '' Vibrio cholerae''. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea that lasts a few days. Vomiting an ...

and

hepatitis Hepatitis is inflammation of the liver tissue. Some people or animals with hepatitis have no symptoms, whereas others develop yellow discoloration of the skin and whites of the eyes ( jaundice), poor appetite, vomiting, tiredness, abdominal ...

are sometimes fly-borne. Other diseases carried by houseflies are

Salmonella ''Salmonella'' is a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two species of ''Salmonella'' are '' Salmonella enterica'' and '' Salmonella bongori''. ''S. enterica'' is the type species and is ...

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, ...

anthrax Anthrax is an infection caused by the bacterium '' Bacillus anthracis''. It can occur in four forms: skin, lungs, intestinal, and injection. Symptom onset occurs between one day and more than two months after the infection is contracted. The s ...

, and some forms of

ophthalmia Ophthalmia (also called ophthalmitis) is inflammation of the eye. It results in congestion of the eyeball, often eye-watering, redness and swelling, itching and burning, and a general feeling of irritation under the eyelids. Ophthalmia can have d ...

. They carry over 100 pathogens and transmit some parasitic worms. The flies in poorer and lower-hygiene areas usually carry more pathogens. Some strains have become immune to most common insecticides.

Cockroach

Cockroaches Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known ...

carry disease-causing organisms (typically

gastroenteritis Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydr ...

) as they forage. Cockroach excrement and cast skins also contain a number of

allergens An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies. In technical ter ...

causing responses such as, watery eyes, rashes, congestion of nasal passages and asthma.

Biting insects

There are many insects that bite including

mosquitoes Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small Diptera, flies within the family Culicidae (from the Latin ''culex'' meaning "gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish ...

, biting midges,

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 "green ...

black flies A black fly or blackfly (sometimes called a buffalo gnat, turkey gnat, or white socks) is any member of the family Simuliidae of the Culicomorpha infraorder. It is related to the Ceratopogonidae, Chironomidae, and Thaumaleidae. Over 2,200 spec ...

, Horse-flies, and

stable flies ''Stomoxys calcitrans'' is commonly called the stable fly, barn fly, biting house fly, dog fly, or power mower fly. Unlike most members of the family Muscidae, ''Stomoxys calcitrans'' ('sharp mouth' + 'kicking') and others of its genus suck bl ...

. Through feeding, insects or other arthropod vectors can transmit diseases to humans. Medical entomologists and other medical professionals have helped to develop

vaccine A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified.

s that can prevent humans from contracting some of those diseases. They have also developed ways to prevent the arthropods from biting humans. According to a study by the

Centers for Disease Control and Prevention 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, Georg ...

published in May 2018, illnesses caused by insect bites have tripled from 2004 to 2016.

Insect-borne diseases

Major

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 characteristic ...

– Vectors: ''

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 l ...

'' (main vector) ''Aedes albopictus'' (minor vector). 50 million people are infected by dengue annually, 25,000 die. Threatens 2.5 billion people in more than 100 countries. *

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. ...

– Vectors: '' Anopheles'' mosquitoes. 500 million become severely ill with malaria every year and more than one million die. *

Leishmaniasis Leishmaniasis is a wide array of clinical manifestations caused by parasites of the trypanosome genus '' Leishmania''. It is generally spread through the bite of phlebotomine sandflies, ''Phlebotomus'' and ''Lutzomyia'', and occurs most freq ...

– Vectors: species in the genus ''

Lutzomyia ''Lutzomyia'' is a genus of phlebotomine sand flies consisting of nearly 400 species, at least 33 of which have medical importance as vectors of human disease. Species of the genus ''Lutzomyia'' are found only in the New World, distributed in ...

'' in the

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...

and ''

Phlebotomus ''Phlebotomus'' is a genus of "sand flies" in the Diptera family Psychodidae. In the past, they have sometimes been considered to belong in a separate family, Phlebotomidae, but this alternative classification has not gained wide acceptance. ...

'' in the

Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by thei ...

. Two million people infected. *

Bubonic plague Bubonic plague is one of three types of plague caused by the plague bacterium ('' Yersinia pestis''). One to seven days after exposure to the bacteria, flu-like symptoms develop. These symptoms include fever, headaches, and vomiting, as wel ...

– Principal vector: '' Xenopsylla cheopis'' At least 100 flea species can transmit plague. Re-emerging major threat several thousand human cases per year. High pathogenicity and rapid spread. * Sleeping sickness – Vector:

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, Glos ...

, not all species. Sleeping sickness threatens millions of people in 36 countries of sub-Saharan Africa ( WHO) *

Typhus Typhus, also known as typhus fever, is a group of infectious diseases that include epidemic typhus, scrub typhus, and murine typhus. Common symptoms include fever, headache, and a rash. Typically these begin one to two weeks after exposure. ...

-–Vectors: mites, fleas and body lice 16 million cases a year, resulting in 600,000 deaths annually. *

Wuchereria bancrofti ''Wuchereria bancrofti'' is a filarial (arthropod-borne) nematode (roundworm) that is the major cause of lymphatic filariasis. It is one of the three parasitic worms, together with ''Brugia malayi'' and '' B. timori'', that infect the lymphatic ...

– most common vectors: the mosquito species: ''

Culex ''Culex'' is a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans, and other animals. The diseases they vector include arbovirus infections such as West Nile virus, Japanese encep ...

'', '' Anopheles'', '' Mansonia'', and ''

Aedes ''Aedes'' is a genus of mosquitoes originally found in tropical and subtropical zones, but now found on all continents except perhaps Antarctica. Some species have been spread by human activity: '' Aedes albopictus'', a particularly invasive sp ...

''; affects over 120 million people. *

Yellow fever Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains – particularly in the back – and headaches. Symptoms typically improve within five days. ...

– Principal vectors: '' Aedes simpsoni'', '' A. africanus'', and '' A. aegypti'' in Africa, species in genus '' Haemagogus'' in South America, and species in genus ''

Sabethes ''Sabethes'' mosquitoes are primarily an arboreal genus, breeding in plant cavities.Ralph E. Harbach. 1994. The subgenus ''Sabethinus'' of ''Sabethes'' (Diptera: Culicidae). ''Systematic Entomology'', 19: 207-234; https://www.researchgate.net/p ...

'' in France. 200,000 estimated cases of yellow fever (with 30,000 deaths) per year.

Minor

Ross River fever Ross River fever is a mosquito-borne infectious disease caused by infection with the Ross River virus. The illness is typically characterised by flu like symptoms combined with polyarthritis and a rash. The virus is endemic to mainland Austral ...

– Vector: Mosquitoes, main vectors '' Aedes vigilax'', '' Aedes camptorhynchus'', and ''

Culex annulirostris ''Culex annulirostris'', commonly known as the common banded mosquito, is an insect native to Australia, Fiji, Micronesia, the Philippines and Indonesia. It is regarded as a serious pest species throughout its range. Frederick Askew Skuse des ...

'' *

Barmah Forest Virus ''Barmah Forest virus'' is an RNA virus in the genus ''Alphavirus''. This disease was named after the Barmah Forest in the northern Victoria region of Australia where it was first isolated in 1974. Or The first documented case in humans was in ...

– Vector: Known vectors ''

'', '' Ocleratus vigilax'' and '' O. camptorhynchus'' and '' Culicoides marksi'' * Kunjin encephalitis (mosquitoes) * Murray Valley encephalitis virus (MVEV) – Major mosquito vector: ''

''. *

Japanese encephalitis Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV). While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases, symptoms may include he ...

– Several mosquito vectors, the most important being '' Culex tritaeniorhynchus''. *

West Nile virus West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family '' Flaviviridae'', from the genus '' Flavivirus'', which also contains the Zika virus, dengue virus, and yellow fever virus. The v ...

– Vectors: vary according to geographical area; in the United States ''

Culex pipiens ''Culex pipiens'', commonly referred to as the common house mosquito, is a species of mosquito. House mosquitoes are some of the most common mosquitoes in the United States. More specifically, ''Culex pipiens'' is considered as the northern hous ...

'' (Eastern US), ''

Culex tarsalis ''Culex tarsalis'', also known as Western Encephalitis Mosquito, is a mosquito species that appears in southern California. The species has black and white banding on the legs. The species is a major vector of Saint Louis encephalitis and West ...

'' (Midwest and West), and ''

Culex quinquefasciatus ''Culex'' is a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans, and other animals. The diseases they vector include arbovirus infections such as West Nile virus, Japanese en ...

'' (Southeast) are the main vectors. *

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the '' Borrelia'' bacterium, which is spread by ticks in the genus '' Ixodes''. The most common sign of infection is an expanding red rash, known as erythema ...

– Vectors: several species of the genus ''

Ixodes ''Ixodes'' is a genus of hard-bodied ticks (family Ixodidae). It includes important disease vectors of animals and humans ( tick-borne disease), and some species (notably '' Ixodes holocyclus'') inject toxins that can cause paralysis. Som ...

'' * Alkhurma virus (KFDV) – Vector:

tick Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living ...

* Kyasanur forest disease – Vector: '' Haemaphysalis spinigera'' * Brugia timori filariasis – Primary vector: '' Anopheles barbirostris'' *

Babesia ''Babesia'', also called ''Nuttallia'', is an apicomplexan parasite that infects red blood cells and is transmitted by ticks. Originally discovered by the Romanian bacteriologist Victor Babeș in 1888, over 100 species of ''Babesia'' have since ...

– Vector: ''Ixodes'' ticks. *

Carrion's disease Carrion's disease is an infectious disease produced by '' Bartonella bacilliformis'' infection. It is named after Daniel Alcides Carrión. Signs and symptoms The clinical symptoms of bartonellosis are pleomorphic and some patients from ende ...

– Vectors: sandflies of the genus ''

''. *

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 co ...

– Vector: assassin bugs of the subfamily ''

Triatominae The members of the Triatominae , a subfamily of the Reduviidae, are also known as conenose bugs, kissing bugs (so-called from their habit of feeding from around the mouths of people), or vampire bugs. Other local names for them used in The Amer ...

''. The major vectors are species in the genera ''

Triatoma ''Triatoma'' is a genus of assassin bug in the subfamily Triatominae (kissing bugs). The members of ''Triatoma'' (like all members of Triatominae) are blood-sucking insects that can transmit serious diseases, such as Chagas disease. Their saliva ...

'', ''

Rhodnius ''Rhodnius'' is a genus of assassin bugs in the subfamily Triatominae (the kissing bugs), and is an important vector in the spread of Chagas disease. The ''Rhodnius'' species were important models for Sir Vincent Wigglesworth's studies of insect ...

'', and '' Panstrongylus''. *

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 r ...

– Vectors: ''

'' mosquitoes * Human ewingii ehrlichiosis – Vector: ''

Amblyomma americanum ''Amblyomma americanum'', also known as the lone star tick, the northeastern water tick, or the turkey tick, or the "Cricker Tick", is a type of tick indigenous to much of the eastern United States and Mexico, that bites painlessly and commonly ...

'' * Human granulocytic ehrlichiosis – Vector: '' Ixodes scapularis'' * Rift Valley Fever (RVF) – Vectors: mosquitoes in the genera ''

'' and ''

'' * Scrub typhus – Vector:

Chigger ''Trombicula'', known as chiggers, red bugs, scrub-itch mites, or berry bugs, are small arachnids (eight-legged arthropods) in the Trombiculidae family. In their larval stage, they attach to various animals, including humans, and feed on skin, ...

Loa loa filariasis ''Loa loa'' filariasis is a skin and eye disease caused by the nematode worm ''Loa loa''. Humans contract this disease through the bite of a deer fly or mango fly (''Chrysops'' spp.), the vectors for ''Loa loa''. The adult ''Loa loa'' filarial ...

– Vector: '' Chrysops'' sp.

References

*Mullen, G. L., and Durden, L. A., eds. 2002. ''Medical and Veterinary Entomology'', Academic Press, NY *ldridge, B. F., and Edman, J. D., eds. 2000. ''Medical Entomology: A Textbook on Public Health and Veterinary Problems Caused by Arthropods''. Kluwer Academic Publishers * Desowitz, R. S. 1991. ''The Malaria Capers''. Norton and Co., New York, NY. *Goddard, J. 2007. ''Physician's Guide to Arthropods of Medical Importance'', Fifth Edition.Boca Raton, FL, CRC Press, *Harwood, R. F., and M. T. James. 1979. ''Entomology in Human and Animal Health''. Macmillan Pub. Co., NY. *Higley, L. G., L. L. Karr, and L. P. Pedigo. 1989. ''Manual of entomology and pest management''. Macmillan Pub. Co., New York, NY—Chapter on medical pests vector and transmitted diseases table. *McNeil, W. H. 1976. ''Plagues and people''. Anchor Press, Doubleday, Garden City, NY. *Service, M. 2008. ''Medical Entomology for Students'' 4th Edition Cambridge University Press. * Zinsser, H. 1934. ''

Rats, Lice and History ''Rats, Lice and History'' is a 1935 book written by biologist Hans Zinsser on the subject of typhus, a disease on which he performed significant research. Zinsser frames the book as a biography of the infectious disease, tracing its path through ...

''. Little, Brown, and Co., New York, NY. {{Infectious disease Subfields of entomology Medical specialties Academic disciplines