Comparative assessment of flotation methods for the detection of Toxoplasma gondii oocysts in soil samples

The aim of the study was to select the optimal method for determining the level of soil contamination by protist oocysts. Soil samples were taken from housing area, playgrounds and other objects of Kazan city to conduct a comparative analysis of flotation methods in terms of their suitability for determining the level of contamination of environmental objects with parasitic protists Toxoplasma gondii oocysts. It was found that the average time per sample when setting modified flotation with zinc sulfate was the smallest - 5 minutes. Centrifuging of suspended soil sample with a Sheather solution takes 15 minutes at 3100 turns/minute. Microscopic studies of the obtained flotates, regardless of the flotation method, in all the samples equally revealed the presence of oocysts of the genera Hammondia, Neospora, Toxoplasma and other morphologically related coccidia. The effectiveness of the application varies based on the complexity of the composition of the working solutions and the duration of the study. The use of formaldehyde in flotation using a Sheather solution and formalin in modified flotation with zinc sulfate does not meet the criteria of simplicity and cheapness. Low efficiency of flotation with sodium chloride is associated with long centrifugation operating cycles, which increase the time of the sample research. The results of this work indicate that sucrose flotation is most effective in terms of component composition and time of the study. Modification of the method with the addition of gelatin increases the degree of purification of oocysts from soil samples, while not complicating the flotation procedure.