Lymphatic filariasis in Brazilian urban area (Maceió, Alagoas)

ABSTRACT

A cross-sectional survey conducted among evening students was used to determine the prevalence of Wucheria bancrofti infection in Maceió, capital of the State of Alagoas, northeast Brazil. A single thick-blood smear was used, being collected between 10 p.m. and 12 a.m. From a total of 29,551 students enrolled at evening elementary schools in the 33 city sectors, 16,569 (56.4 per cent) were random selected for inclusion in the studt. From those, 10,857 (65.5 per cent) were interviewed and examined and 73 (0.7 per cent) were found to have microfilaraemia. Autochthonous W. bancrofti carriers live in 10 of the 33 city sectors, suggesting a focal distribution. Moreover, 84 per cent of infections were diagnosed among 29 per cent of all students examined, inhabiting three contiguous sectors at the city central area, presenting infection rates up to 5.3 per cent. Students living in city sectors with prevalence of microfilariae carriers greater than 1 per cent were found to have a higher risk for infection when compared to students from the rest of the town [Relative Odds (RO) 12.8, 95 per cent CI 6.7 - 25.1]. Eleven positive individuals from non endemic areas were living in Maceió for more than 10 years; time of residence in the area was a major risk factor for infection among students not born in the region (p<0.01). Regarding sex, male students presented a higher proportion of positive (RO 1.7, 95 per cent CI 1.1 - 2.9).