Study of the distribution of Paragonimus in Pingyuan County in Eastern Guangdong.

Objective To investigate the distribution of Paragonimus in Pingyuan County,eastern Guangdong Province.Methods Freshwater snails and crabs from Muxi,Guowu,Yanziao,Wuzhishi,and Tazili townships were studied.Cercariae and metacercariae of Paragonimus were detected.Domestic cats were inoculated artificially with detected metacercariae and used for further detection.Results The rate of Paragonimus infection in snails was 1‰(2/2 000)in Muxi and 0.5‰(1/2 000)in both Guowu and Yanziao.All snails were found to be Semisulcospira libertina.The rate of Paragonimus metacercariae infection in crabs in the same five areas was 55.36%(62/112),65.26%(62/95),48.38%(60/124),35.13%(52/148),and 36.75%(43/117),respectively.A mixed infection of Pw,Ps and Ec was found in Muxi and Guowu,a mixed infection of Pw and Ps was found in Yanziao,and a mixed infection of Pw and Ec was found in both Wuzhishi and Tali.Six adults and two larvae of Pw,eight adults of Ps,and four adults of Ec were found in six domestic cats inoculated with Paragonimus.Conclusion Muxi Township in Pingyuan County is considered to be a major focus of infection for a mixture of Pw,Ps,and Ec.Guowu,Yanziao,Wuzhishi,and Tazili were newly identified as major foci of infection.In addition,dominant species of freshwater crabs were identified to be Sinopotamon pinheense,which are as the second intermediate hosts of Paragonimus appearing in Pingyuan County.