ABSTRACT
Objective To understand the current status of the sanitation of freshwater aquaculture environments ,and Clo-norchis sinensis infection of freshwater fish in the aquaculture and market in a city of Pearl River Delta region,so as to provide the evidence for formulating the prevention and control strategy of clonorchiasis sinensis. Methods In 2016,based on the dis-tribution of freshwater aquaculture,36 freshwater fish ponds among 14 towns were selected for sampling and investigation,and 10-20 pieces were collected from each pond. Besides,3 aquatic product wholesale markets were included,among which 3-6 stalls were selected from each market,and 20-30 pieces were collected from each stall. The metacercaria in the fish was exam-ined by the digestion method. Results In the 36 fish ponds,there were no toilets with the stool being drained into fish ponds di-rectly,and there was only one pond with duck sheds with the stool being drained into fish ponds directly. Totally 437 pieces of freshwater fish from ponds were detected,with a metacercaria positive rate of 4.35％(19/437). The metacercaria positive fish were distributed in 50％(7/14)of towns and 25％(9/36)ponds. The positive rates of crucian carp,grass carp,dace,aristich-thysnobilis,and tilapia were 13.95％(6/43),4.76％(9/189),4.44(2/45),1.55％(2/129),and 0(0/31)respectively,with statistically significant difference(χ2=13.46,P=0.01). Totally 307 pieces of freshwater fish were collected from the wholesale markets,with a total positive rate of 1.95％(6/307). The positive rate of grass carp and aristichthysnobilis were 3.20％(4/125) and 2.78％(2/72)respectively,and no positive samples were found in crucian carp,dace and tilapia,with no statistically sig-nificant difference among the different fish in the infection rate(Fisher exact P=0.75). Conclusions The sanitation of fresh-water aquaculture environments in a city of Pearl River Delta region is relative good. However,there are different degrees of Clo-norchis sinensis infection of freshwater fish in some aquaculture environments and markets.