Researchers' mathematical model provides chagas diseas...( e model was developed in close connecti...)

T. cruzi is spread through the feces of domestic blood-feeding bugs called triatomines, also known as "kissing bugs" (with local names such as "vinchuca," "chipo," or "barbeiro").

Domestic triatomine bug populations start to grow in Argentina during the spring. Part of the bug population growth is fueled by blood meals the bugs take from chickens, which during the spring are kept indoors to brood protected from theft or predation.

Chickens cannot be infected with T. cruzi whereas dogs and humans can be. But the infected dogs are much more infectious to the bugs than the infected humans, and therefore fuel population growth of both bugs and T. cruzi.

By the time the chickens roost outdoors in the summer, the already large domestic bug population shifts to feed preferably on dogs and secondarily on humans, which rapidly spreads the prevalence of T. cruzi among bugs. This in turn increases the infection rate among dogs and humans.

Because triatomine bugs are more likely to feed on chickens and dogs than on humans, summer infection rates grow for humans as people share domestic sleeping quarters with infected dogs.

The mathematical model provides thirteen predictions about the transmission of T. cruzi. Two of them greatly affect human health:

• keeping dogs in the bedroom is "the worst thing householders can do," with respect to Chagas disease;
• and exclusion of infected dogs from sleeping areas will virtually eliminate transmission of the parasite, at least in semi-arid settings like those studied in the Gran Chaco region.

"Because of budget constraints in spraying programs in Latin America, it might take ten years to get around to spraying all the rural villages. But it only takes t
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Contact: Lynn Love
lovel@rockefeller.edu
212-327-8977
Rockefeller University
25-Jul-2001