[Studies on ecology of Fasciolopsis buski and control strategy of fasciolopsiasis].

The development of eggs of Fasciolopsis buski requires oxygen and the eggs cannot survive anaerobic conditions. The eggs have some resistance to low temperature and can be maintained at 4 degrees C for 3 to 4 months; however, the eggs are killed at 50 degrees C in four hours. The presence of salts can influence the development time of the eggs and reduce their hatching rate. Encysted cercariae exist not only on aquatic plants, but also on the surface of the water. The number of encysted cercariae floating on the water surface is about 3.6% of that of the total encysted cercariae. By inquiring into the case history we found that 10.3-12.8% of the patients and 35.1-40% of the infested pigs were possibly infected by drinking water contaminated with encysted cercariae. The authors suggest the use of fermented silage to feed pigs instead of fresh aquatic green fodders to prevent infection in the animals. In addition, aquatic plants such as water chestnut should be boiled for 1 to 2 minutes before eating to kill the encysted cercariae on the plants.