The results of the National Survey on Prevalence of Schistosomiasis Mansoni and Geohelminthiasis, a study conducted by Fiocruz Minas under the coordination of researcher Naftale Katz, show a reduction in the number of cases of these diseases throughout the country. The rate of positivity for schistosomiasis fell to 1%, a significant drop compared to previous investigations, which recorded a rate of 10% in 1953 and 6.9% in 1977.
Regarding geohelminthiasis, the decrease in the number of people infected is even greater, in all locations investigated. In Maranhão, for example, the proportion of schoolchildren positive for geohelminths was 99.4% in 1953, and currently stands at around 20%. In Minas Gerais, where rate was 89.4%, in the latter survey it was 1.4% for Ascaris, 0.9% for hookworms and 0.60% for Trichuris.
In order to conduct the research, were examined 197,564 students residing in 521 municipalities, distributed by the 27 units of Federation and Federal District, between the years of 2010 and 2015. This is a cross-sectional, population-based study, whose purpose is to know the current situation of schistosomiasis, trichuriasis, ancylostomiasis and ascariasis, in schoolchildren between aged 7 to 17 years, of both genders.
For the authors of the survey, the reduction in parasite positivity rates can be attributed to urbanization and sanitation, that is, the supply of domestic water and sewage that had a significant growth in this period. According to the researchers, it is also necessary to consider the millions of specific treatments that have been carried out for decades in Brazil, with medicines of low toxicity that produce few side effects.
However, they point out that such improvements, especially in relation to sanitary sewer system, have been occurring at a slow pace, which reinforces the concern with the effects of changes in both sanitation policies and social policies aimed at eliminating the conditions of poverty, all of which have a strong impact on the prevalence rates of the diseases under investigation.