Rat infestation associated with environmental deficiencies in an urban slum community with high risk of leptospirosis transmission / Infestação por roedores associada a fatores ambientais numa comunidade carente com alto risco de transmissão da leptospirose / Infestación por roedores asociada a factores ambientales en una comunidad sin recursos con alto riesgo de transmisión de la leptospirosis

Abstract: We analyzed environmental factors that provide food, water and harborage to rodents and the risk of household rodent infestation in a slum community with a high risk of leptospirosis transmission. Detailed environmental surveys were performed in 221 households. Multivariate regression models evaluated the association between rodent infestation and socioeconomic status and environmental attributes obtained from Geographical Information System surveys. The general household infestation rate was 45.9%. Rattus norvegicus signs were the most prevalent, present in 74% of the infested households. The risk for rodent infestation was associated with environmental factors supporting harborage for rats, such as dilapidated fences/walls (OR: 8.95; 95%CI: 2.42-33.12) and households built on an earthen slope (OR: 4.68; 95%CI: 2.23-9.81). An increase of 1 meter from the nearest sewer was associated with a 3% (95%CI: 1%-5%) decrease in the risk of rodent infestation. A lack of sanitation where poor people live provides factors for rat infestation and could the target of educational interventions.

Resumo: O estudo analisou fatores ambientais que facilitam a presença de alimento, água e abrigo para roedores e risco de infestação por roedores numa comunidade com alto risco de transmissão da leptospirose. Foram realizados inquéritos ambientais detalhados em 221 domicílios. Modelos de regressão multivariada avaliaram a associação entre infestação por roedores e nível socioeconômico e atributos ambientais obtidos através de inquéritos com Sistemas de Informação Geográfica. O estudo mostrou uma taxa global de 45,9% de infestação domiciliar. Sinais de Rattus norvegicus eram os mais prevalentes, presentes em 74% dos domicílios infestados. O risco de infestação por roedores esteve associado a fatores ambientais que forneciam abrigo aos ratos, tais como cercas e muros dilapidados (OR: 8,95; IC95%: 2,42-33,12) e domicílios construídos diretamente sobre encostas (OR: 4,68; IC95%: 2,23-9,81). Cada incremento de um metro de distância a partir do esgoto mais próximo esteve associado a uma diminuição de 3% (IC95%: 1%-5%) no risco de infestação por roedores. A falta de saneamento básico nos locais de moradia das famílias pobres facilita a infestação por ratos e é alvo prioritário para intervenções educativas.

Resumen: El estudio analizó factores ambientales que facilitan la presencia de alimento, agua y abrigo para roedores y el riesgo de infestación por roedores en una comunidad sin recursos con alto riesgo de transmisión de la leptospirosis. Se realizaron encuestas ambientales detalladas en 221 domicilios. Los modelos de regresión multivariada evaluaron la asociación entre infestación por roedores, nivel socioeconómico y características ambientales, obtenidos a través de encuestas con Sistemas de Información Geográfica. El estudio mostró una tasa global de un 45,9% de infestación domiciliaria. Los indicios de Rattus norvegicus eran los más prevalentes, presentes en un 74% de los domicilios infestados. El riesgo de infestación por roedores estuvo asociado a factores ambientales que proporcionaban abrigo a las ratas, tales como cercas y muros derruidos (OR: 8,95; IC95%: 2,42-33,12) y domicilios construidos directamente sobre pendientes (OR: 4,68; IC95%: 2,23-9,81). Cada incremento de un metro de distancia, a partir del alcantarillado más próximo, estuvo asociado a una disminución de un 3% (IC95%: 1%-5%) en el riesgo de infestación por roedores. La falta de saneamiento básico en las viviendas de las familias pobres facilita la infestación por ratas y es el objetivo prioritario para intervenciones educativas.

Characterization of protective and non-protective surface membrane carbohydrate epitopes of Schistosoma mansoni

We have produced a number of monoclonal antibodies, protective and non-protective, which recognize a complex of schistosomula antigens, including the 38 kDa antigen. Eight different protective and non-protective monoclonal antibodies, varying in isotypes, were used in the binding assays. Lectin inhibition studies suggested that the monoclonal antibodies probably recognized carbohydrate epitopes on the antigen(s). Immunoprecipitation studies showed that at least two of the monoclonal antibodies recognized different epitopes on the same molecule. Additionally, we tested for monoclonal antibody binding after the antigens were treated with; 1) proteases, 2) periodate, 3) various exo- and endoglycosidases, 4) mild acid hydrolysis. We also tested for binding of the antibodies to keyhole limpet hemocyanin (KLH). Using the 8 monoclonal antibodies as probes, we were able to define at least 4 different carbohydrate epitopes related to the protective monoclonal antibodies, and at least one epitope which is seen by the non-protective antibodies. The epitope seen by the non-protective antibodies was shown to be cross-reactive with epitopes on KLH. These results demonstrate the importance of epitope mapping studies for any defined vaccine.