Influence of variables on centrifuge-flotation technique for recovery of Toxocara canis eggs from soil Influência de variáveis na técnica de centrífugo-flutuação para a recuperação de ovos de Toxocara canis em solo

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Vamilton Alvares Santarém, Luciana Puga Magoti, Tathiana Dias Sichieri
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 2009
• Subjects: Toxocara canis eggs; Recovery technique; Soil contamination; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic; Partida
• Online Access: https://doi.org/10.1590/S0036-46652009000300007; https://doaj.org/article/a36bbc4743fc45e2ba4fd7de874546c8

The purpose of this study was to evaluate the influence of variables in a flotation technique for the recovery of Toxocara canis eggs from soil. The trials were done under standardized conditions on one gram of previously sterilized soil samples contaminated with 200 eggs of T. canis. The following variables were evaluated in serial steps: sieving; type of wash; time of stirring; resuspension of sediment; solution flotation. Centrifuge-flotation in sodium nitrate (d = 1.20 g/cm³) was adopted as an initial technique, using Tween 80 (0.2%) and decinormal sodium hydroxide as solutions for washing the samples. Ten tests were done to compare the variables, using counting in triplicate. The sieving of the material reduced significantly the recovery of eggs (p < 0.001) and the number of eggs recovered was higher when the sediment was resuspended (p < 0.05). After standardization, flotation solutions sodium chloride, zinc sulfate, sodium dichromate, magnesium sulfate, and sodium nitrate (d = 1.20g/cm³) were compared. The best results were obtained by using zinc sulfate solution. In conclusion, the chances of recovering T. canis eggs from samples using flotation solutions can be increased by washing of soil twice using distilled water, and resuspension of sediment. On the other hand, the sieving procedure can drastically reduce the number of eggs. Com o objetivo de avaliar a influência de variáveis na técnica de centrífugo-flutuação para a recuperação de ovos de Toxocara canis em solo, amostras de solo foram previamente esterilizadas e divididas em alíquotas de um grama e contaminadas com 200 ovos. Após contaminação, foram comparadas, em etapas seriadas, as variáveis: filtragem, tipo de lavagem e ressuspensão do material. Como ponto de partida, utilizou-se técnica com lavagem de solo em Tween 80 (0,2%) e solução de hidróxido de sódio 0,1N; ressuspensão; e centrífugo-flutuação em solução de nitrato de sódio (d = 1,20 g/cm³). Os ovos recuperados foram contados com 10 repetições e três leituras para cada repetição. A ...