Triatoma infestans or "kissing bug", together with other triatomine bugs, are responsible for the transmission of Chagas' disease amongst humans. Triatominae are insects of the order Hemiptera, family Reduviidae, subfamily Triatominae.The vectors live in rural areas in the houses of the poor people where they find shelter in the roof and the walls. During the night the bugs leave their hiding place and feed on the skin of the sleeping inhabitants. In heavily infested houses sometimes thousands of triatomine bugs (or "Vinchucas" in Spanish) can be found and it is not exceptional that people living in these houses will be bitten more than a 100 times per night. Considering that each Vinchuca may take up upto 1ml of blood per meal, it can easily be understood that some people tend to develop a chronic form of aneamia. Unfortunately in some regions of South America it is considered to indicate "luck and happiness" to have vinchucas in the house.
While Triatoma feeds it defecates on the the human skin
While the bug sucks the blood from its victim, it defecates on the host's skin at the same time that it feeds, and the metacyclic trypomastigotes that develop in the hindgut of the insect enter the host's body, most often by being "rubbed in" to the vector's bite or the mucous membranes of the eye, nose, or mouth, where they establish an infection.
Prophylaxis
The use of insecticides for the spraying of houses in rural areas, the use of insecticide-containing paints and of fumigants to sterilize the houses, has been extremely effective in reducing the rate of transmission of Chagas' disease. WHO has reported that in 1997 transmission in Argentina has been interrupted and a similar success is expected soon in Brasil.
Serological tests remain positive in the intermediate stage of the disease and parasitaemia, though not detectable by parasitological methods, can be recognized by xenodiagnosis in 20 - 60 % of cases.
Triatoma infestans is also used for "xenodiagnosis" of Chagas' disease in humans. Bugs that are grown in the laboratory are fed on the skin of suspected Chagas' patients. When trypanosomes are ingested together with the blood these develop in the gut and hind gut of the insect and after dissection of the insect a few weeks later they can be seen with the microscope.
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