Survey on the natural focus of angiostrongyliasis in Guangdong Province

Objective To understand the distribution status of angiostrongyliasis natural focus in Guangdong Province and provide the scientific basis for making surveillance program.Methods Survey sites were chosen by the lamination sampling according to different geographic locations.Different species of freshwater snails and terraneous snails were collected in wild fields for detecting the infection by homogenization and lung dissection methods.Rats were captured for dissecting lung tissues to detect the parasite.Fresh rat feces were collected for etiological detection.Results Totally 17 survey sites were sampled in these four regions including 5 in the Pearl River Delta,5 in East Guangdong,5 in West Guangdong and 2 in North Guangdong.Plentiful Pomacea canaliculatas were found in all of these sites.The survey of Achatina fulica was not carried out in Guangning County.Achatina fulicas were found in surveyed districts,except for Heping County of Heyuan and Qujiang District of Shaoguan.Totally 3 329 Pomacea canaliculatas and Achatina fulicas were collected in 17 survey sites.The snails with Angiostrongylus cantonensis infection were found in 16 of 17 survey sites,except for Xuwen County.The mean infection rate was 6.64%(221/3 329).The infection rates and infection intensities of Achatina fulica were far higher than those of Pomacea canaliculata in all sites.89 round river snails and 252 stone snails were bought in agricultural trading markets,of which only one stone snail from Luoding was found positive,with a positive rate of 1.43%(1/70).In rattus flavipectus captured from Heping County,Leizhou and Zhongshan cities,Angiostrongylus cantonensis adult worms were found,with a positive rate of 11.11%(3/27).Thirty-four cases of fresh mouse feces were collected,with a positive rate of 44.12%(15/34).Conclusion The natural focus of angiostrongyliasis cantonensis distributed widely in Guangdong Province and there were both Pomacea canaliculata and Achatina fulica distributing in all areas except for some mountainous areas of North Guangdong,where no Achatina fulica was found.The intermediate and definitive hosts were with Angiostrongylus cantonensis infection in different levels.