Socioeconomic conditions as determining factors in the prevalence of systemic and ocular toxoplasmosis in Northeastern Brazil.

Objective: To determine the prevalence of systemic and ocular toxoplasmosis among 1024 students in the city of Natal, Northeastern Brazil, and correlate it with demographic, socioeconomic and epidemiological risk factors.

Methods: The study population was randomly selected, asked to fill out a questionnaire, provide a blood sample for IgG and IgM (MEIA) serology and a hemogram, and undergo an eye examination.

Results: The seroprevalence for IgG was 46% (95% CI = 42.9-49.2%) and that for IgM was 1.4% (95% CI = 0.8-2.4%). The prevalence of ocular lesions was 1.15% (95% CI = 0.6-2.0%). In the univariate analyses, confirmed by multivariate analysis, the socioeconomic conditions were determinants in the prevalence of systemic and ocular toxoplasmosis (mother's schooling = literacy/OR = 2.9 and p < 0.001).

Conclusions: The prevalence of systemic toxoplasmosis, although high, was lower than that found in studies performed in the South and Southeast of Brazil, and the incidence of ocular lesions was totally different, being lower by a factor varying from 5 to 17. Although important epidemiological variables, such as owning a cat, drinking unfiltered water or having had contact with lakes or rivers, were found to be correlated with toxoplasmosis in the preliminary analysis, they lost their influence when included in the logistic model. However, further studies must be undertaken to identify the reasons for these findings, including the determination of the strains of Toxoplasma gondii encountered in different regions of the country and the sources of the water utilized by these populations.