DEVELOPMENT OF FASCIOLA-HEPATICA EGGS IN OUTDOOR TEMPERATURES IN TEMUCO, SOUTHERN CHILE

A two-year study on the development of Fasciola hepatica eggs under ou tdoor conditions was carried out in Temuco, southern Chile (38-41S, 72 -25W). Eggs obtained from bile of infected cattle were placed in bucke ts in a medium of distilled water once a month, and examined at monthl y intervals: until 50% had hatched. The shortest period of development was 37 days in eggs placed outside in January, 1990. The longest peri od required for development was 249 days for eggs placed outside in Ap ril 1988. Eggs placed outside in March failed to hatch in autumn and r emained viable throughout the winter; most of them hatched in October or November. It was proved that liver fluke eggs do not have a paralle l development and that the time taken to hatch vary within each sample . The hatching stage only occurred when the mean temperature was more than 10 degrees C. It can be concluded that in outdoor conditions, the development time is influenced by environmental temperature, latitude of the habitat and that no hatching occurs below an average temperatu re of 10 degrees C.