Anti-Toxocara antibodies detected in children attending elementary school in Vitoria, State of Espirito Santo, Brazil: prevalence and associated factors

Introduction: The aim of this study was to evaluate the frequency of anti-Toxocara antibodies in serum from 7-year-old children attending elementary school in Vitoria-ES, Brazil and to correlate these antibodies with socio-demographic factors, the presence of intestinal helminths, blood eosinophil numbers, past history of allergy or asthma, and clinical manifestations of helminth infections. Methods: The detection of anti-Toxocara antibodies was performed using an ELISA (Cellabs Pty Ltd) on serum from 391 children who had already been examined by fecal examination and blood cell counts. Data from clinical and physical examinations were obtained for all children. Results: The prevalence of anti-Toxocara antibodies was 51.6%, with no gender differences. No significant differences were observed between positive serology and the presence or absence of intestinal worms (60.3 and 51.7%, respectively; p = 0.286). The only variables significantly related to positive serology were onycophagy and the use of unfiltered water. Although eosinophilia (blood eosinophil count higher than 600/mm(3)) was significantly related to the presence of a positive ELISA result, this significance disappeared when we considered only children without worms or without a past history of allergy or asthma. No clinical symptoms related to Toxocara infection were observed. Conclusions: There is a high prevalence of anti-Toxocara antibodies in children attending elementary schools in Vitoria, which may be partially related to cross-reactivity with intestinal helminths or to a high frequency of infection with a small number of Toxocara eggs.