Fatores determinantes da manutenção da transmissão da esquistossomose mânsonica em área endêmica do Ceará

Abstract

Schistosomiasis caused by Schistosoma mansoni is a very important disease from a public health perspective. Although, the disease is focused its distribution is worldwide. The infection can determine clinical disease which hamper the laborious capacity of individuals and reduce the quality-adjusted life years. Recently, control programmes based in treatment, sanitation, supply of clean water and chemical control of snails have had a significant impact on the morbidity of this parasitosis, mainly due to reduction of the intensity and prevalence of infection. The endemic area for schistosomiasis in Ceara, was delimited in 1977, and it includes 2,972 villages over 16 municipalities. The control programme has been implemented, systematically and uniformly, in all endemic villages of Ceara for 20 years. Some villages have displayed a dramatic decrease in the intensity and prevalence of infection, although other did not. This study aims to describe the factors involved in the maintenance of transmission of schistosomiasis in an area under pressure of control over 20 years. Specifically, we compared the prevalence of risky behaviors, environmental risk factors, density and natural infection rate of snails from villages with high transmission with those from low transmission villages. We have concluded that some risk factors were more prevalent in high transmission villages, and others had similar prevalence in both group of villages. Moreover, the low transmission villages were in a lower degree of urbanization, in order that the man-water contact were more frequent there. Despite a lower exposure to water in the high transmission area, the likelihood of infection was higher because the environment exposes individual to a higher burden of the parasite expressed by a higher density and natural infection rate of snails in the higher transmission area.