RESUMO
Objective To investigate the ecological habit and characteristics of Trichobilharzia cercariae in the Huaihe river system. Methods During June of 2002-May of 2003, Radix auricularia snails were collected monthly in Yaohe Fishery of the branch of the Huaihe River. The cercariae, released from the positive snails and collected by Shade Drop Bottle, were examined by direct press. Ducklings were infected by cercariae with different ages and examined for the infection by miracidia hatching method.Results The results showed a typical seasonal fluctuation in infection rate of the snails, i.e. the cercariae detection rate was 0.81% in July, 0.65% in June, 0.07%-0.26% in April, May, August, September and October respectively, with a significant difference (? 2=26.73, P