Factors associated with the presence of helminth eggs in the soil of public areas in Concepción, Chile.

The aim of this study was to assess the association between the distance to the nearest feces, the type of substrate to be studied (feces, soil, grass), and whether a given area was licensed or not with the presence of helminth eggs in Concepción, Chile. A total of 256 samples taken from feces and either from soil or grass at 10 cm, 50 cm, and 100 cm from feces (including 16 public areas), were examined for the presence of parasites using the ZnSO4 technique. The association between variables with the presence of eggs was assessed with multifactorial logistic regressions. 24.21% of samples presented at least one egg. The higher odds of Toxocara egg presence was positively associated with the licensed 'area type' and the soil 'sample type' (when compared with feces). The odds of Ancylostomatidae egg presence was positively associated with the licensed 'area type', but negatively associated with the soil 'sample type' (compared with feces). The results suggest that finding eggs must be interpreted differently based on the parasite species and substrate to be analyzed, and that the presence of parasitized dogs is a more important contributing factor than the frequency with which the ground is cleaned of feces.