Low-tech prescription for Chagas.

• Author: Hardman, Chris
• Position: IOjo! - Brief Article

CHAGAS DISEASE is a serious and sometimes deadly infection that affects some sixteen to twenty million people throughout the Americas. What if there were a simple and inexpensive way to prevent transmission?

Rockefeller University and Columbia University professor Joel E. Cohen and Ricardo Gurtler from the University of Buenos Aires say there is, and they have the scientific data to prove it. Cohen and Gurtler are combining their expertise in applied mathematics and tropical infectious diseases to develop mathematical models to solve health problems.

According to the World Health Organization, Chagas disease is endemic to twenty-one countries in the Americas, where one hundred million people are at risk of contracting the disease. The infection is life-long and in its most severe form can lead to heart failure. Humans contract the disease from the Trypanosoma cruzi parasite. The parasite is transmitted to humans through an infected blood transfusion or through the feces of the blood-sucking reduviid bug, locally known as "kissing" bugs, "cone-nosed" bugs, vinchuca, or barbeiro.

Cohen and Gurtler set out to learn how the parasite spreads in rural households. They created a mathematical model based on a decade of data from three rural villages in northwest Argentina. The first model of its kind, it processes data from household populations of bugs, parasites, and their relationship to the numbers of humans, chickens, and dogs living within a household.

The results show that transmission follows a seasonal pattern based on what animals live in the house at what time. The cycle begins in the spring, when humans, dogs, and chickens all sleep inside together--a safeguard against chicken theft or predation. The bugs also live inside, and they feast on the chickens, finding them to be an ideal source of a blood meal. Although chickens can't be infected with the parasite, their presence in the household increases the bug population, which peaks in the summer when the chickens are usually moved outside. The bugs then turn to the dogs as their secondary choice...