Isolation of Eimeria oocysts from soil samples: a simple method described in detail

Abstract

Molecular methods are currently available to detect parasitic DNA in soil, but do not replace the need for direct parasitological methods that can identify the extent of contamination. This report describes an inexpensive and fast flotation method for retrieving Eimeria oocysts from soil that requires few tools. Soil samples were experimentally contaminated with 50,000 E. bovis oocysts and compared with soil-free controls. A separate experiment tested the effect of mechanical stress by shaking the soil and oocyst mix 0, 1, 5, and 10 times before attempting to retrieve the oocysts. The percentage of oocysts retrieved using the flotation method was 22%, which was similar to the results obtained with previously described, more labour-intensive methods. The presence of soil reduced the percentage of oocysts that could be retrieved by 23%. A single shake of the oocysts and soil mixture was sufficient to significantly reduce the recoverable proportion of oocysts. The results indicated that the developed simple method can be applied to recover oocysts, and that gentle handling of soil samples prior to oocyst isolation is important.

Keywords

• Eimeria
• soil
• diagnosis
• contamination
• flotation
• method