Environmental contamination with Toxocara eggs and seroprevalence of toxocariasis in children of northeastern Poland

Toxocariasis is a worldwide distributed zoonotic disease. Soil contaminated with Toxocara eggs appears to be the main source of infection for humans. The aim of our study was to estimate the environmental contamination with Toxocara eggs in public areas in northeastern Poland followed by the assessment of seroprevalence of toxocariasis in the children's population inhabiting the areas. A total of 168 soil samples were collected in June and September from public areas, and 28 from patients' residences. They were all examined for Toxocara eggs using the centrifugal flotation technique. Two-step serological tests comprising enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) were performed in 190 children aged 2-17 without any symptoms of toxocariasis. The positive samples accounted for 36 and 32 % in the urban area, 39 and 18 % in the suburbs, and 39 and 46 % in parks, for June and September, respectively. All the sites located near the patients' residences with confirmed persistent toxocariasis were found contaminated with Toxocara eggs. A significant drop in the mean number of eggs was noted in the suburbs after summer (0.64 vs 0.18, p<0.05). High and constant contamination was documented in soil from urban sandboxes and parks. The overall seroprevalence in children tested for toxocariasis was 4.2 % as determined by ELISA and WB (3.0 % in preschool children and 7.7 % in school children). The current study revealed high contamination of public areas in northeastern Poland with Toxocara eggs as well as marked seroprevalence in asymptomatic children. There is an urgent need to introduce and promote preventive health measures to limit spread of toxocariasis.