Toxoplasmosisand mental retardation: report of a case; control study

A case-control study evaluating the association between mental retardation and toxoplasmosis was conducted among 845 school children in Belo Horizonte, MG, Brazil. Cases (450) were mentally retarded children attending a public school for special education. Controls (395) were children from the regular public school system. Clinical and anthropometric examinations and interviews were carried out to determine risk factors for toxoplasmosis and mental retardation. Diagnosis of Toxoplasma gondii infection was based upon an indirect immunofluorescent test (IFA); 55% of cases and 29% of controls were positive. The Relative Odds of mental retardation in children with positive serology was 3.0 (95% CI 2.2-4.0). Maternal exposure to cats and contact with soil were associated with an increased risk of mental retardation. Retinochoroiditis was fourfold more prevalent among cases than controls and was only diagnosed in T. gondii IFA positive participants. Congenital toxoplasmosis, in its subclinical form, appears to be an important component in the etiology of mental retardation, especially in high risk (lower socio-economic) groups. The population attributable risk was estimated as 6.0 - 9.0%, suggesting the amount of mental retardation associated with this infection

Epidemiology of Schistosoma mansoni infection in a low-endemic area in Brazil: clinical and nutritional characteristics

A cross-sectional case-control study designed to evaluate the role of malnutrition in the association between the intensity of Schistosoma mansoni infection and clinical schistosomiasis, was conducted in an area with both low frequency of infection and low morbidity of schistosomiasis in Brazil. Cases (256) were patients with a positive stool examination for S. mansoni; their geometrical mean number of eggs/gram of feces was 90. Controls (256) were a random sample of the negative participants paired to the cases by age, sex and length of residence in the area. The clinical signs and symptoms found to be associated with S. mansoni infection, comparing cases and controls, were blood in stools and presence of a palpable liver. A linear trend in the relative odds of these signs and symptoms with increasing levels of infection was detected. Adjusting by the level of egg excretion, the existence of an interaction between palpable liver and ethnic group (white) was suggested. No differences in the nutritional status of infected and non-infected participants were found