Epidemiologia da esquistossomose mansoni em São José do Acácio, MG.: Análise multivariada dos fatores associados à infecção. Variáveis sócio-demográficas e contatos com águas naturais

Abstract

A cross sectional study of schistosomiasis mansoni was undertaken in Sao José do Acacio (in the municipality of Engenheiro Caldas, Minas Gerais) with the aim of evaluating the distribution in the population of indicators of schistosomiasis (prevalence, intensity of infection and distribution of clinical forms), describing the patterns of water contact in the population and determining the risk factors for infection with Schistoggmg mansoni in this endemic area. The study population consisted of all the residents in the urban zone of the district of São José do Acacio. The total population of the locality was 766 individuals of whom 678 (88.5%) were submitted to fecal examination, 627 (81.9%) to clinical examination and 746 (97.4%) were included in a socio-demographic survey. Infection with S.mansoni was determined by fecal examination by the KATO/KATZ method. The socio-demographic survey and water contact studies were done by interview with standardized questionnaires using a double blind protocol . For the study of risk factors, socio-demographic characteristics and the reasons for water contact of individuals Who were eliminating S. mansoni eggs in their feces (cases) were compared with those of individuals not eliminating eggs in their feces (controls). The prevalence of infection was 26.2%, the geometric mean of the number of eggs per gram of feces was 60.3 (CI 95% = 4.4 - 826.3) and 2.4% of those infected presented splenomagaly. Fifty-one percent of the population studied reported at least one contact with fresh water in the 60 days proceeding the interview: 34% in order to cross streams, 25% to bathe and/or swim, 17% to fish, 17% for work associated with irrigation, 4% to collect sand 2% to wash clothes and 1% to collect water for the home and/or wash dishes. The following variables showed independent association with infection: age (Odds Ratios adjusted by logistic regression = 3.0, 12.1 and 4.2 for the age groups 10 -14, 15 34 and 35 and over, respectively), absence of a source of water (tank) in the home (OR = 2.8), sex (OR = 2.6) and water contacts for swim ing and/or bathing (OR = 1.9 and 2.3 for weekly and daily contacts, respectively) and fishing (OR = 1.2 and 4.6 for weekly and daily contacts, respectively). It was shown that the absence of a water tank in the home was the most important risk factor for infection with 55 mansoni in the study area (Attributable risk = 0.2488) followed by water contact for bathing or swimming (AR = 0.1526 and 0.0599 for weekly and daily contacts, respectively) h and fishing (AR = 0.0289 and 0.00886) for weekly and daily contacts, respectively). This indicates that efforts of preventing infection with 55 mansoni in this endemic area should take the increase of availability of water in the home and intervention to prevent contact with natural water for bathing and/or swim ing and fishing as priorities.