[Seroprevalence of Triatoma infestans Chagas disease after vector control measures]

The study is part of a project intended to retrieve information about the serology of the American trypanosomiasis in the state of São Paulo, Brazil, during the period when there was a state effort to control the vector. Data from the municipality of Taquarituba, administrative region of Sorocaba, which was then important in the epidemiology of Chagas disease in that region, were analyzed. Despite the government efforts started in the 1950s, domiciliary triatomines were still being captured in that region during the 1970s.

Population samples were selected from five localities of Taquarituba. Age, sex, birthplace, and time of residence in the house being occupied at the time of the interview, were recorded. It is used Probit analysis to assess a possible relationship between age and seropositivity, the latter taken as indicative of the risk of transmission.

Blood from Taquarituba native people represented 62.9% of the samples examined (n = 2.784) and 62.4% of all seropositives (n = 380). Overall proportion of seropositives was 13.6% with no significant difference between genders (p = 0.538). Children under 6 years of age were not seropovitive, Seropositivity increased from 2.7% in the age group 6-9 years to 30.6% in the age group 30-39 years. By using probit analysis, an age-seropositivity relationship was found within these groups.

The results of serological tests pointed to an association between the actions taken against Triatoma infestans and the decline and eventual control of the transmission of Chagas disease in the late 1960s.