Cross-sectional and evolutive studies of schistosomiasis mansoni in untreated and mass treated endemic areas in the southeast and northeast of Brazil

Abstract

Cross-sectional and evolutive studies on schistosomiasis mansoni were carried out before and after mass treatment in the endemic areas of Capitão Andrade and Padre Paraiso, state of Minas Gerais, Riachuelo, state of Sergipe, Alhandra, state of Paraiba, and Aliança, Alegre and Coroatá, lowland of the state of Maranhão, Brazil, in the last eighteen years. The studies included clinical and fecal examination by the Kato-Katz quantitative technique, skin test for Schistosoma mansoni infection, evaluation of man-water contact and other epidemiological investigations such as infection rate and dynamic of the snail population. Results showed: (1) Higher prevalence of S. mansoni infection, greater egg load elimination and higher and earlier morbidity of the chronic forms of the disease in the southeast areas of Capitão Andrade and Padre Paraiso; (2) The incidence of hepatosplenic form is higher in some family clusters, in whites and mulattos in all the endemic areas but develop earlier in the southeast; (3) The prevalence and morbidity of schistosomiasis are decreasing both in the mass treated northeast and in the untreated southeast areas; (4) The mass treatment reduces rapidly the prevalence of the infection and the morbidity of the disease but can not control it because of the frequent reinfections due to the intensity of man-water contact.

Epidemiological and control aspects of schistosomiasis in Brazilian endemic areas

“…During the decades of 50 and 60, many pioneering works were developed by Pessoa et al (1953Pessoa et al ( , 1955Pessoa et al ( , 1957 in Brazilian Northeast, Brener and Mourão (1956), Rodrigues da Silva (1957), Klotzel (1962Klotzel ( , 1963 Katz and Brener (1966), Barbosa (1966Barbosa ( , 1968, Prata and Schroeder (1967), and Prata and Bina (1968), about morbidity and disease evolution, in areas of Minas Gerais, Alagoas, Pernambuco, and Bahia and many others cited by Coura et al (1980Coura et al ( -1992, which resume epidemiological, laboratorial and clinical studies about the disease until that time.…”

“…More recently, Katz (1992, 1998) Coura et al (1992, Bina (1992) Barbosa and Coimbra Jr. (1992), Kloetzel (1992), Barbosa (1995), and Coura (1995) reviewed the epidemiological situation and suggested controlling actions for disease in Brazil, while Hiroshi Kano (1992) and Amaral and Porto (1994) analyzed the controlling actions adopted by National Health Foundation (Fundação Nacional de Saúde -Funasa).…”

Clinical and laboratory evaluation of schistosomiasis mansoni patients in Brazilian endemic areas

“…According to Coura et al (1992), the policy of mass treatment of the population during the 1980s in areas considered to have high prevalence and the repeated treatments of re-infections may have contributed to a better control of the morbidity caused by schistosomiasis due to a weaker infection intensity as measured by the low parasite load.…”

A thirty years follow-up study on Schistosomiasis mansoni in a community of Minas Gerais, Brazil

“…A survey on the natural history of infection with S. mansoni in Capitão Andrade, MG, conducted in 1973(Conceição 1976 identified high prevalence and morbidity in the autochthonous population, especially when compared to populations from other endemic areas in Brazil evaluated by the same group of researchers (Coura et al 1992). The results obtained during this phase showed a prevalence of infection of 60.8% in Capitão Andrade, with 5.6% of hepatosplenic forms, and 0.6% of infantilism.…”