Abstract. Environmental, demographic, and entomologic variables were analyzed by logistic multiple regression analysis for their association with the likelihood of being seropositive for Trypanosoma cruzi in three highly infested rural villages of northwest Argentina. The prevalence of seropositivity for T. cruzi, as determined by the composite results of three serologic tests, was 34% among 338 persons in 1992. The strongest positive predictors of the adjusted odds of being infected were the household number of dogs, the density of T. cruzi-infected Triatoma infestans in bedroom areas, and each person's age. Dwellers from houses with roofs made completely or partly with a grass called simbol, or which used insecticides rudimentarily and nonsystematically, had a significantly lower odds of being seropositive for T. cruzi than residents from other types of dwellings. The adjusted odds of infection also increased with the number of T. cruzi-infected dogs or cats and the presence of chickens in bedroom areas. No significant effects on the adjusted odds of infection of a community-wide deltamethrin spraying carried out in one of the villages seven years before were detected. Socioeconomic indicators, such as domiciliary area, and numbers of corrals and livestock, were inversely related to being infected. Our study identified several manageable variables suitable for control actions, most of them not examined before in univariate or multivariate analyses. Environmental management based on low-cost housing with appropriate local materials and removal of domestic animals from domiciliary areas have a crucial role to play in the control of Chagas' disease in rural areas.Chagas' disease is highly prevalent in the Chaco, a natural landscape unit of about 1,000,000 km 2 extending over northern Argentina, Bolivia, Paraguay, and southwestern Brazil. In this region, Triatoma infestans is the main or only domiciliary vector of Trypanosoma cruzi, the causative agent of Chagas disease, and mud-and-thatch houses are the typical rural dwellings. 1,2 The Chaco is one of the most endemic regions for Chagas' disease in the Americas, where an estimated 16-18 million people are infected and an additional 90 million people are at risk of contracting the infection. 3 Although mud-and-thatch houses are usually regarded as homogeneous, the density of triatomines varies widely among them for reasons that are becoming increasingly understood. Triatomine infestation is closely connected to thatched roofs and cracked or unplastered walls, 4-7 the household number of resident people, 8 and the presence of dogs and hens in bedroom areas. 9,10 In northwest Argentina, houses with thatched roofs made of simbol (Pennisetum sp., a long-leaved grass arranged in compact bundles), walls well-plastered with mud, and where domestic insecticides were rudimentarily and nonsystematically applied by house dwellers had a significantly lower density of Triatoma infestans and dog infection rates with T. cruzi than other typical rural dwellings. 9,11 Studying the...
