Chagas disease is fatal, but difficult to catch. So people are infected, they need to scratch where a blood sucking insect known as the kissing bug has both bits and defecated on them. The itching is scratching feces-loaded with a single-celled parasite called Trypanosoma cruzi -in the skin, but the process is so inefficient that only a human is infected for every 1,700 kissing bug bites. So why nearly 40% of people in some South American communities infected T. cruzi ? At least in Arequipa, Peru, the answer may be guinea pigs, according to a study published online today in the Proceedings of the Royal Society B . Rodents, which are farmed as food in the Andean region, can act as reservoirs of T. cruzi , the infecting bugs lying around their pens and suck their blood. If there was much to balance their uninfected guinea pigs infected friends, this might not be such a problem. But Guinea pig populations rise and fall in a predictable cycle: When the alfalfa prices peak in the dry months of summer, people kill their stock rather than pay more to feed them. (It does not hurt that summer has several holiday which traditionally involve pig Guinea cookouts in the Andes.) If the remaining guinea pigs arrive to transport T. cruzi , the parasite is concentrated in a smaller population . This, in turn, makes it more likely a bug will bite hunger embracing a Guinea pig infected instead of a healthy, transforming the insect in a vector capable of passing along T. cruzi for meals to come, including humans. And this seems to be exactly what is happening in Arequipa. After many years of this cycle, more than 80% of triatomine took two Guinea pig pens have been infected there T. cruzi while only 6% of the sampled insects far rodent enclosures were. Unfortunately, the insects that live near guinea pigs also live close to people, increasing the chance that T. cruzi will find its way into human hosts and maintain the rate of Chagas high
* Correction, June 18, 1:26 p.m. :. This product was called the bug embrace a kind of beetle, which is incorrect. It belongs to the family Reduviidae called insects.
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