Chagas' disease in São Paulo State: a comparative study between systematic search and inhabitants' report of bugs in the area under entomological surveillance

Entomological surveillance of Chagas' disease in São Paulo State has adopted a scheme that uses the locality as a unit for field work. Actions are prioritized according to infestation levels obtained by systematic search of triatomine (routine actions), bugs in areas with high infestation levels and in houses whose inhabitants report the presence of the bugs (reply to notification). The most prevalent triatominic species in Sao Paulo State at present are Triatoma sordida and Panstrongylus megistus. A comparative study of infestation levels obtained in houses and surroundings in routine search and replies to notification in the two-year periods of 90/91, 92/93 and 94/95, has shown average percentage positivity of 1.3 indoors in routine activity and 6.2 in the reply to notification. For the house surroundings the values were 8.6 and 18.2 respectively, no differences being found between the two-year periods. Replies to notification showed average percentage positivity (focus) in 26% of the houses. It was verified that the notifications had come from localities with prior infestation levels equal to zero (I = O), intermediary infestation levels (I < 5) and high infestation levels (I > 5), although the percentages of positive replies to notification were higher in those localities with high prior infestation levels. These results reinforce the importance of notification in the surveillance of vector species of the invasive type like those currently prevalent in Sao Paulo State.