{"id":151,"date":"2009-03-12T09:56:49","date_gmt":"2009-03-12T09:56:49","guid":{"rendered":"http:\/\/openstream.tv\/zanzare\/?p=151"},"modified":"2014-03-17T11:51:37","modified_gmt":"2014-03-17T11:51:37","slug":"andreas-krueger","status":"publish","type":"post","link":"https:\/\/www.openstream.tv\/zanzare\/andreas-krueger\/","title":{"rendered":"Andreas Krueger"},"content":{"rendered":"

Tabanids and their medical importance<\/strong><\/p>\n

Andreas Krueger<\/strong>
\nGerman Armed Forces \u2013 Hospital Hamburg, Dept. Tropical Medicine at the Bernhard Nocht Institute for Tropical Medicine, Labgroup Medical Entomology. Bernhard-Nocht Str. 74, 20359 Hamburg, Germany<\/p>\n

Tabanids (clegs, horse flies, deer flies) belong in the order Diptera to the \u201clow\u201d infraorder Tabanomorpha and are represented with over 3500 species worldwide, predominantly in the tropics.
\nMost of the 160 or so European species are confined to the Mediterranean area. Only the females feed blood on mammals including humans. They are usually diurnal and exophilic as well as
\nexophagous. They develop in (semi-)aquatic or terrestrial habitats. The optical remote perception of the host is steered by large, dark, heat-emitting objects (also cars!). Tabanids are good and fast
\nfliers, and a potential host is pursued actively by them.
\nAdult Tabanus species can be larger than 2 cm. The eyes of many tabanids have a species-specific, brightly coloured pattern of spots or stripes. For Chrysops species dark-brownish wing patterns are
\ncharacteristic, while in Haematopota species the wings are greyishly mottled and typically kept roof-like over the abdomen. In particular, the clearly segmented antennae distinguish tabanids from
\n\u201chigher\u201d flies. The mouthparts superficially resemble the sponging labella of the cyclorrhaph flies.
\nHowever, they accommodate stylet-like mandibles and laciniae for piercing the host skin, which leads straight to their medical and economic importance: on one hand the robust proboscis causes
\nquite painful bites and leaves, on the other hand, relatively large, after-bleeding wounds. These can attract other flies and be thus entrance gates for various secondary infections. In addition, the saliva may cause toxic effects. A massive nuisance of domestic animals can lead to growth inhibition and
\nreduced milk production. Of special interest is the role of tabanids in the cyclic or mechanical transmission of pathogens to humans and animals. Some Chrysops spp. act as obligatory vectors of
\nthe filaria Loa loa (Nematoda: Spirurida, Onchocercidae), the causative agent of human loiasis disease in Central Africa, where approx. 10 million humans are infected. By migrating of the adult
\nfemale worms in the connective tissue (hence the German name \u201eWanderfilarie\u201c) it comes to swelling (\u201eCalabar\u201c- or \u201eCameroon swelling\u201c) as well as to provoking of the eyes, if the worm
\nmoves under the conjunctiva.
\nExperimental data suggest the possibility of the mechanical transmission of numerous pathogens,
\nbut the situation in the field is widely unclear. Due to the specific behaviour of tabanids, i) short time feeder (at least Tabanus spp.), ii) causing after-bleeding wounds, iii) predominant zoophily,
\nand the association of high population densities during respective disease outbreaks, at least a veterinary meaning must be derived for viruses (equine infectious anemia virus, EIA virus), for bacteria (Bacillus anthracis, Francisella tularensis) as well as for certain protozoa of the genus Trypanosoma. Regarding anthrax only once from India species-related data were given for an outbreak, whereby Tabanus indianus, T. bicinctus (=T. biannularis) and Haematopota montana were incriminated. Eventually, in South America tabanids can act as phoretic vehicles for the eggs
\nof the myiasis-causing human bot-fly Dermatobia hominis.<\/p>\n","protected":false},"excerpt":{"rendered":"

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