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Disease Vectors
In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen such as a parasite or microbe, to another living organism. Agents regarded as vectors are mostly blood-sucking ( hematophagous) arthropods such as mosquitoes. The first major discovery of a disease vector came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected the stomach tissue of a mosquito. Arthropods Arthropods form a major group of pathogen vectors with mosquitoes, flies, sand flies, lice, fleas, ticks, and mites transmitting a huge number of pathogens. Many such vectors are haematophagous, which feed on blood at some or all stages of their lives. When the insects and ticks feed on blood, the pathogen enters the blood stream of the host. This can happen in different ways. The '' Anopheles'' mosquito, a vector for malaria, filariasis, and various arthropod-borne-viruses ( arboviruses), inserts its delicate mouthpart under the skin and feeds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anopheles Stephensi
''Anopheles stephensi'' is a primary mosquito vector of malaria in urban India and is included in the same subgenus as ''Anopheles gambiae'', the primary malaria vector in Africa. ''A. gambiae'' consists of a complex of morphologically identical species of mosquitoes, along with all other major malaria vectors; however, ''A. stephensi'' has not yet been included in any of these complexes. Nevertheless, two races of ''A. stephensi'' exist based on differences in egg dimensions and the number of ridges on the eggs; ''A. s. stephensi'' ''sensu stricto'', the type form, is a competent malaria vector that is found in urban areas, and ''A. s. mysorensis'', the variety form, exists in rural areas and exhibits considerable zoophilic behaviour, making it a poor malaria vector. However, ''A. s. mysorensis'' is a detrimental vector in Iran.Sinka, M.E., Bangs, M.J., Manguin, S., Chareonviriyaphap, T., Patil, A.P., Temperley, W.H., Gething, P. W., Elyazar, I.R.F., Kabaria, C.W., Harbach, R.E., ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haematophagous
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 proteins and lipids that can be taken without great effort, hematophagy is a preferred form of feeding for many small animals, such as worms and arthropods. Some intestinal nematodes, such as Ancylostomatids, feed on blood extracted from the capillaries of the gut, and about 75 percent of all species of leeches (e.g., '' Hirudo medicinalis'') are hematophagous. The spider '' Evarcha culicivora'' feeds indirectly on vertebrate blood by specializing on blood-filled female mosquitoes as their preferred prey. Some fish, such as lampreys and candirus; mammals, especially vampire bats; and birds, including the vampire finch, Hood mockingbird, Tristan thrush, and oxpeckers, also practise hematophagy. Mechanism and evolution Hematophag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onchocerca
Onchocerca is a genus of parasitic roundworm. It contains one human parasite – '' Onchocerca volvulus'' – which is responsible for the neglected disease Onchocerciasis, also known as "river blindness" because the infected humans tend to live near rivers where host black flies live. Over 40 million people are infected in Africa, Central America, and South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o .... , Indiana State University. Accessed 14 February 2008. Other species affect cattle, horses, etc. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leishmania
''Leishmania'' () is a genus of parasitic protozoans, single-celled eukaryotic organisms of the trypanosomatid group that are responsible for the disease leishmaniasis. The parasites are transmitted by sandflies of the genus '' Phlebotomus'' in the Old World, and of the genus '' Lutzomyia'' in the New World. There are 53 species and about 20 of them are responsible for human infections. They are transmitted by around 100 species of sandflies. The primary hosts are vertebrates. They commonly infect hyraxes, canids, rodents, and humans. History Members of an ancient genus of ''Leishmania''-like parasites, '' Paleoleishmania'', have been detected in fossilized sand flies dating back to the early Cretaceous period. The first written reference to the conspicuous symptoms of cutaneous leishmaniasis surfaced in the Paleotropics within oriental texts dating back to the 7th century BC (allegedly transcribed from sources several hundred years older, between 1500 and 2000 BC). D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 blindness due to infection, after trachoma. The parasitic worm is spread by the bites of a black fly of the ''Simulium'' genus. Usually, many bites are required before infection occurs. These flies live near rivers, hence the common name of the disease, River blindness. Once inside a person, the worms create larvae that make their way out to the skin, where they can infect the next black fly that bites the person. There are a number of ways to make the diagnosis, including placing a biopsy of the skin in normal saline and watching for the larva to come out, looking in the eye for larvae, and looking within the bumps under the skin for adult worms. A vaccine against the disease does not exist. Prevention is by avoiding being bitten by flies. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
African Trypanosomiasis
African trypanosomiasis is an insect-borne parasitic infection of humans and other animals. Human African trypanosomiasis (HAT), also known as African sleeping sickness or simply sleeping sickness, is caused by the species ''Trypanosoma brucei''. Humans are infected by two types, ''Trypanosoma brucei gambiense'' (TbG) and ''Trypanosoma brucei rhodesiense'' (TbR). TbG causes over 92% of reported cases. Both are usually transmitted by the bite of an infected tsetse fly and are most common in rural areas. Initially, the first stage of the disease is characterized by fevers, headaches, itchiness, and joint pains, beginning one to three weeks after the bite. Weeks to months later, the second stage begins with confusion, poor coordination, numbness, and trouble sleeping. Diagnosis involves detecting the parasite in a blood smear or lymph node fluid. A lumbar puncture is often needed to tell the difference between first- and second-stage disease. Prevention of severe disease in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leishmaniasis
Leishmaniasis is a wide array of clinical manifestations caused by protozoal parasites of the Trypanosomatida genus ''Leishmania''. It is generally spread through the bite of Phlebotominae, phlebotomine Sandfly, sandflies, ''Phlebotomus'' and ''Lutzomyia'', and occurs most frequently in the tropics and sub-tropics of Africa, Asia, the Americas, and southern Europe. The disease can present in three main ways: Cutaneous leishmaniasis, cutaneous, mucocutaneous leishmaniasis, mucocutaneous, or visceral leishmaniasis, visceral. The cutaneous form presents with skin ulcers, while the mucocutaneous form presents with ulcers of the skin, mouth, and nose. The visceral form starts with skin ulcers and later presents with fever, low red blood cell count, and enlarged spleen and liver. Infections in humans are caused by more than 20 species of ''Leishmania''. Risk factors include poverty, malnutrition, deforestation, and urbanization. All three types can be diagnosed by seeing the paras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Fly
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 species of black flies have been formally named, of which 15 are extinct. They are divided into two subfamilies: Parasimuliinae contains only one genus and four species; Simuliinae contains all the rest. Over 1,800 of the species belong to the genus '' Simulium''. Most black flies gain nourishment by feeding on the blood of mammals, including humans, although the males feed mainly on nectar. They are usually small, black or gray, with short legs and antennae. They are a common nuisance for humans, and many U.S. states have programs to suppress the black fly population. They spread several diseases, including river blindness in Africa (''Simulium damnosum'' and ''S. neavei'') and the Americas (''S. callidum'' and ''S. metallicum'' in C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, Glossinidae. The tsetse is an obligate parasite, which lives by feeding on the blood of vertebrate animals. Tsetse has been extensively studied because of their role in transmitting disease. They have pronounced economic and public health impacts in sub-Saharan Africa as the Vector (epidemiology), biological vectors of trypanosomes, causing African trypanosomiasis, human and animal trypanosomiasis. Tsetse can be distinguished from other large flies by two easily-observed features: primarily, tsetse fold their wings over their abdomens completely when they are resting (so that one wing rests directly on top of the other); Secondly, tsetse also have a long proboscis, extending directly forward, which is attached by a distinct bulb to the bottom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phlebotominae
The Phlebotominae are a subfamily of the family Psychodidae. In several countries, their common name is sandfly, but that name is also applied to other flies. The Phlebotominae include many genera of blood-feeding ( hematophagous) flies, including the primary vectors of leishmaniasis, bartonellosis, and pappataci fever. Sandflies are small; a body size of about 3 mm in length is typical for many species, which aids them in escaping notice. Their bite is not always felt, but leaves a small, round, reddish bump that starts itching hours or days later. Use of insect repellent is recommended in areas where sandflies are present. Diet and reproduction Phlebotomine sandflies have a diet that includes both blood and plant-derived sugar meals. Phlebotomine females, and only females, suck blood from various mammals, reptiles, and birds, while both sexes consume sugary substances including nectar, honeydew, and phloem sap from plants. Some species are selective about their hosts, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salivary Gland
The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary glands can be classified as serous, mucous, or seromucous (mixed). In serous secretions, the main type of protein secreted is alpha-amylase, an enzyme that breaks down starch into maltose and glucose, whereas in mucous secretions, the main protein secreted is mucin, which acts as a lubricant. In humans, 1200 to 1500 ml of saliva are produced every day. The secretion of saliva (salivation) is mediated by parasympathetic stimulation; acetylcholine is the active neurotransmitter and binds to muscarinic receptors in the glands, leading to increased salivation. A proposed fourth pair of salivary glands, the tubarial glands, were first identified in 2020. They are named for their location, being positione ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arbovirus
Arbovirus is an informal name for any virus that is Transmission (medicine), transmitted by arthropod Vector (epidemiology), vectors. The term ''arbovirus'' is a portmanteau word (''ar''thropod-''bo''rne ''virus''). ''Tibovirus'' (''ti''ck-''bo''rne ''virus'') is sometimes used to more specifically describe viruses transmitted by ticks, a superorder within the arthropods. Arboviruses can affect both animals (including humans) and plants. In humans, symptoms of arbovirus infection generally occur 3–15 days after exposure to the virus and last three or four days. The most common clinical features of infection are fever, headache, and malaise, but encephalitis and viral hemorrhagic fever may also occur. Signs and symptoms The incubation period – the time between when infection occurs and when symptoms appear – varies from virus to virus, but is usually limited between 2 and 15 days for arboviruses. The majority of infections, however, are asymptomatic. Among cases in which sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
