A comparative study between commonly used laboratory flotation methods for recovering helminth eggs from sand samples

Abstract

Animal fecal deposition in the environment is a public health problem with a potential risk for pathogenic agents like parasites. In epidemiological surveys, the evaluation of soil contamination requires an efficient d easy method for the isolation of parasite eggs from soil samples. The present study was performed aiming to compare flotation methods to test their efficacy in recovering helminth eggs from 50 sand samples, from a sandy area, in the city of Porto Alegre, Rio Grande do Sul State, Brazil. For Kazacos and Faust et al. methods, Zinc sulphate (d=1.35) was used as flotation solution and in Ruiz et al. method, sucrose solution (d=1.2g/ml). Fifty replicated examinations were performed for each type of flotation method. The results were expressed as the number of T. canis eggs recorded and/or percentage rates of recovery in sand samples. Our findings include the presence of 7/50 (14%) samples with Toxocara spp eggs; and 1/50 (2%) sample with Ancylostomidae-like
eggs. The Kazacos method (30g) detected four (4/7) positive samples; Faust et al. (30g) detected two (2/7) positive samples, Faust et al. (6g) detected one (1/7) positive sample, and the Ruiz et al. method detected two (2/7) positive samples. These data showed no differences between the flotation methods used in this study for Toxocara eggs recovery.