Human leptospirosis in a slum area in the city of Rio de Janeiro, Brazil: a serological and epidemiological study

Abstract

A serologic survey was carried out on slum dwellers in the city of Rio de Janeiro. A total of 259 serum samples from male and female individuals of different age groups were tested for the presence of antileptospire antibodies by microagglutination. Prevalence data were analyzed in relation to the major risk factors present at the site, mainly represented by the presence of carrier animals and the occurrence of frequent floods. Of the samples tested, 25% reacted with antigens of different serogroups at titres ranging from 1:100 to 1:6400, with a predominance of titres less than or equal to 1:400; 35% of positive sera reacted with leptospirae of the Icterohaemorrhagiae serogroup. Reactions with Djasiman, Panama, Javanica, Canicola, Pyrogenes, Australis, Ballum, Sejroe, Bataviae, Grippotyphosa, Autumnalis and Cynopteri were also detected, though at lower frequencies. There was no statistically significant difference between sexes, but higher prevalence rates were found to be associated with increasing age. A focus of infection was characterized, in which social and economic factors contribute to the persistence of leptospirae by favoring the proliferation of the main reservoir.

Factors associated with Leptospira sp infection in a large urban center in northeastern Brazil

“…However, individual and ecological analysis showed that Leptospira sp was inversely associated with education level. The seroprevalence (12.4%) observed in Salvador was lower than what has been reported from other regions of Brazil 24 and other developing countries 19 , where it ranged from 25.0 to 54.2%. It should be noted, however, that the highest levels have been reported among selected populations living in high-risk areas where leptospirosis is hyperendemic or where there is a high degree of exposure.…”

Sex Bias in Infectious Disease Epidemiology: Patterns and Processes

“…Serological evidence of exposure to Leptospira spp. in Brazil [80]–[83] shows a moderately higher risk among males: a random-effects meta-analysis of four surveys ( N  = 3996 subjects) yielded an OR of 1.41 (95%CI 1.18–1.69) (Figure 4). …”

The place behind the case: leptospirosis risks and associated environmental conditions in a flood-related outbreak in Rio de Janeiro

“…In this sense, slums can be considered endemic areas for leptospirosis, yet displaying low incidence rates during the outbreak. A survey performed in one of the lowland Rio de Janeiro slums demonstrated a human serological prevalence as high as 25 %, with an infection rate of 1% per year (Pereira & Andrade, 1990). In such cases, infection is found to be related to occupational and behavioral factors, presenting a typically endemic evolutionary pattern (Velazquez et al, 1984).…”