Effects of pesticides and temperature on sporulation and viability of cyclospora cayetanensis
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Outbreaks of Cyclospora cayetanensis had been associated with raspberries, basil and lettuce. The leading hypotheses in the raspberry associated outbreaks were that fungicidal spray water used on raspberry fields was contaminated with the parasite. Three different fungicides including captan, benomyl and zineb and two different insecticides including diazinon and malathion were tested on C. cayetanensis at different dilutions and exposure time. Sporulation was observed at all exposure times starting from the lowest of 30 minutes to highest of 1 week from low to high concentrations of pesticides. A reduction in sporulation was observed only with benomyl. At one week benomyl decreased sporulation at the highest concentration of fungicide (0.03 g/10mL i.e. 2.5 lb/100gal). The temperature of exposure and the length of time affected sporulation of Cyclospora cayetanensis on food substrates like basil and dairy produce. In dairy products as food substrate e.g., milk, diluted milk and whipped cream, sporulation was not observed at -15°C for 24 hrs. With basil as a food substrate, sporulation was observed until 48 hrs at -20°C, 1 hr at 50°C and 4 days at 37°C, however no sporulation occurred at temperatures of -70°C, 70°C and 100°C. Temperature studies on oocysts in water showed similar results except that basil protected oocysts at freezing and heating temperatures more than water, thereby having higher sporulation percentages.