Prevalence of parasites in soil and dog feces according to diagnostic tests

The objective of this study was to determine the prevalence of parasites in soil and dog feces according to diagnostic tests. We studied soil from 25 public squares in Seropédica, Brazil. Five samples of soil were collected from each square. Eighty-one fresh fecal samples from dogs were analyzed. The technique described by Dunsmore et al. and an adaptation of the Rugai et al. method were used to recover parasites in soil, and the Willis, Hoffman and Centrifugal-Flotation techniques were used to detect parasites in feces. The chi(2) and Fischer's exact tests were used to analyze the statistical significance of the results. Seven squares were found to be contaminated, and the most prevalent parasites were Ancylostoma spp. (13.6%) and Toxocara spp. (4.0%). The Dunsmore et al. technique and the adaptation of the Rugai et al. method did not differ in the detection of Toxocara spp. (p=0.21), Trichuris spp. (p=0.25), Ascaris spp. (p=0.49) and Strongyloides spp. (p=0.49) in soil. However, the two methods differed in the detection of Ancylostoma spp. eggs (p=0.029) and larvae (p=0.001). According to granulometric analysis, the soil samples consisted mainly of sand (from 96.6% to 82.8%). Parasites were detected in 75 fecal samples, the most frequent being Ancylostoma spp. (80.1%), Toxocara spp. (11.1%) and Cryptosporidium spp. (7.4%). There was no difference between the Willis and Centrifugal-Flotation techniques in the detection of Ancylostoma spp., and both techniques were better than the Hoffman technique for detecting this parasite in feces. The Hoffman and Centrifugal-Flotation techniques were different (p=0.03) in Toxocara spp. detection. No difference was observed among these three for Cryptosporidium spp. detection. The prevalences of zoonotic parasites in both dog feces and soil have implications for the spread of human disease in these areas.