Abstract: Abstract: Objective   To understand the infection status of Clonorchis sinensis in freshwater fish in some areas in  Anhui Province for evidence in prevention and control of this trematode. Methods  Fresh water fish samples were collected from the fish farm, fish markets and catering industries located in Dangtu County, Hexian County, Jingxian County, Shouxian County, Suixi County, Taihe County and Lingbi County between 2019 and 2021. One sample is defined as a kind of freshwater fish obtained at different sampling time, sampling place and sampling link. The sampling quantity of each freshwater fish shall not be less than 500 g. The sample proportion of positive rate of Clonorchis sinensis in the collected samples was detected by digestive microscopy, polymerase chain reaction (PCR) and loop mediated isothermal amplification (LAMP), and analyzed. Results   Thirty-nine monitoring sampling sites for Clonorchis sinensis in freshwater fish were set up in Anhui Province between 2019 and 2021. In total, 298 freshwater fish samples were collected, including 51 species like Pseudorasbora parva, Abbottina rivularis, Hemiculter leucisculus, Hypophthalmichthys molitrix, Aristichthys nobilis and Ctenopharyngodon idellus. From 2019 to 2021, the sample proportion of positive rate of Clonorchis sinensis in freshwater fish at monitoring sites in Anhui Province were 8.16% (8/98), 3.65% (5/137) and 7.93% (5/63) respectively. Clonorchis sinensis was detected in fresh water fish samples from 6 out of 7 counties investigated. The sample proportion of positive rate of Clonorchis sinensis in fresh water fish was higher in Dangtu County and Lingbi County, 11.54% (3/26) and 11.11% (2/18), respectively. Clonorchis sinensis was detected in the fresh water fish samples collected from fish farm, market and catering sectors. The sample proportion of positive rate was 7.81% (10/128), 5.77% (6/104) and 3.03% (2/66), respectively sampled from fish farm, market and catering sectors. There was no significant difference in the sample proportion of positive rate among the three sampling sectors (χ²=1.775, P＞0.05). The sample proportion of positive rate of Clonorchis sinensis was 12.14% (17/140) for small fish species, such as Pseudorasbora parva, Abbottina rivularis and Hemiculter leucisculus, and 0.60% (1/158) for other fish species. The difference was statistically significant (χ²=17.327, P<0.05). Conclusion   The sample proportion of positive rate of Clonorchis sinensis in freshwater fish is relatively higher in some areas in Anhui Province, and small species of fish are most hit. Following work should be focus on strengthening the monitoring of freshwater fish and supplying publicity and education on food safety in order to reduce the risk of Clonorchis sinensis infection in population.

Key words: Clonorchis sinensis, Metacercaria, Freshwater fish, Infection, Survey, Anhui Province