Removing domestic animals from the bedroom may significantly reduce transmission
By characterizing the discrete population dynamics of an individual household, and by collecting data for many individual households to serve as an empirical base, a Rockefeller University researcher and his Argentinean colleague have identified improved control tactics for a vexing public health problem.
A mathematical model called a system of nonlinear difference equations indicates that the chronic, frequently fatal Chagas disease infection could be avoided or greatly reduced in humans in the Gran Chaco region of South America by barring domestic animals from bedrooms. Chagas disease, or American trypanosomiasis, is caused by infection with the protozoan parasite Trypanosoma cruzi and occurs predominantly in rural Latin America. Some cases have also been reported in the southern U.S.
The research provides an immediate and practical defense against the disease, complementing the more commonly implemented insecticide spraying and housing improvement controls.
"The mathematical model is a way of putting together everything we know about household transmission of infection, to see how all the pieces of the puzzle affect the bottom line, human infection," says Joel E. Cohen, head of the Laboratory of Populations at The Rockefeller University and Columbia Universitys Earth Institute.
"The model makes it possible to do, inside of a computer, experiments that we could not ethically do in a real household, such as hypothetically varying the number of infected dogs without trying to reduce the number of infected bugs. Our simple mathematics gives insight attainable no other way."
Reporting in the July 27 edition of Science, Cohen and Ricardo E. Grtler of the University of Buenos Aires predicted how four populationsbugs, chickens, dogs and peopleinteract with T. cruzi each season in an individual household.