Effects of Reagents and Chemicals Used in Existing Sanitation Helminth Test Methods on the Viability of Ascaris suum Eggs

Various sanitation methods to recover helminth eggs are currently in use; however, no international standard exists. Development of such a method first involves testing the effects of all reagents used in current methods on helminth egg viability to determine whether these chemicals affect the test organism. This study was conducted to investigate the effects on viability and development of Ascaris suum eggs when exposed for various periods to wash solutions (water, ammonium bicarbonate, Tween® 20, Tween® 80, Triton® X-100, Sunlight® Liquid, bentonite, and 7X®), flotation solutions (zinc sulfate, magnesium sulfate, sodium nitrate, brine, and sucrose), extraction solutions (10% formalin, acetoacetic buffer, acid-alcohol, ethyl acetate, and diethyl ether), extraction combinations (10% formalin + ethyl acetate, 10% formalin + diethyl ether, acetoacetic buffer + ethyl acetate, acetoacetic buffer + diethyl ether, and acid-alcohol + ethyl acetate), and incubation solutions (water, 0.1 N sulfuric acid, physiological saline, and 0.5%, 2%, and 5% formalin). Ammonium bicarbonate and 7X® performed best as wash solutions (including for overnight soaking), and zinc sulfate is recommended for flotation for up to 30 min of exposure. Individually, all extraction solutions had minimal effects on egg viability, and in combination, acid-alcohol and ethyl acetate did not impact egg viability for up to 15 min of exposure. Postincubation, sulfuric acid allowed optimal egg development and clear samples for microscopy.