Seroprevalence of Chagas disease of Triatoma infestans after vector control measures

Introduction The study is part of a project intended to retrieve informatio n about the serology of the American trypanosomiasis in the state of Sao Pa ulo, Brazil, during tho period when there was a state effort to control the vector. Data from the municipality of Taquarituba, administrative region o f Sorocaba, which was then important in the epidemiology of Chagas disease in that region, were analyzed. Despite the government efforts started in th e 1950s, domiciliary triatomines were still being captured in that region d uring the 1970s. Methods Population samples were selected from five localities of Taquaritub a. Age, sex, birth-place 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 t aken as indicative of the risk of transmission. Results Blood from Taquarituba native people represented 62.9% of the sampl es examined (n = 2.784) and 62.4% of all seropositives (n=380). Overall pro portion of seropositives was 13.6% with no significant difference between g enders (p=0.538). Children under 6 years of age were not seropositive. Sero positivity increased from 2.7% in the age group 6-9 years to 30.6% in the a ge group 30-39 years. By using probit analysis, an age-seropositivity relat ionship was found within these groups. Conclusions The results of serological tests pointed to an association betw een the actions taken against Triatoma infestans and the decline and eventu al control of the transmission of Chagas disease in the late 1960s.