Summary
The results are given of a serological investigation on the incidence of antibodies against Leptospira serotypes in the area known as Humboldt, Município of Aripuanã, Mato Grosso State, Brazil. Of 234 sera from local inhabitants, 22 (9.40%) showed antibodies by the micro agglutination test. Titres of 1:100 were considered as significant in view of the fact that this was an epidemiological survey and not a clinical study. Antibodies were demonstrated against the following serotypes: panama, bataviae, andamana, tarassovi, butembo, wolffi, javanica, brasiliensis, pyrogenes, celledoni e castellonis. Of these, the first three were most prevalent. The incidence of positive reactions was 1.56% in 128 persons under the age of 20 and 18,86% in those of 20 years and upwards. With regards the incidence in different sexes, positive sera were recorded in 8.39% of 131 men and 10.67% of 103 women. Among wild animals, 5 of 50 rodents examined gave positive reactions, 3 of 29 bats, and 1 of 3 wild pigs. No positives were recorded in 16 monkeys, 9 marsupials and 27 birds. Serotypes encountered in these animals were: celledoni, brasiliensis and shermani in rodents, australis and javanica in bats, and brasiliensis in the single, positive wild pig. The results of this study are discussed in terms of ecology, activities of the local inhabitants, and other factors related to the serological data obtained.