Survey Of Infectious Status Of Freshwater Fish With Metacercaria (Clonorchis Sinensis) In Jinzhou

ObjectiveTo investigate the infection of Metacercaria ( Clonorchis sinensis ) in freshwater fishes in Jinzhou and provide basis for formulating a prevention and control measures for relevant departments.Methods10 species of freshwater fish totally 1386 speciments were taken from five trading markets in Jinzhou, Heishan, Yixian, Linhai and Beizhen. Direct compression was used to check the the infection rate of metacercaria of Clonorchis sinensis, and the pepsin-HCl artificial digestion method was used to check the average degree. The data was statistical analysed by Chi-square test.ResultsMetacercaria of Clonorchis sinensis(MC) were discovered in all ten species of freshwater fish. Our results showed there were important differences in the positive rate of MC across the different species of fish (χ~2=632.97,P<0.001). Infection rate of Hypophthalmichthys nobilis, Hypophthalmichthys molitrix, Parasilurus asotus, Perccottus glehni, Erythroculter ilishaeformis, Phoxinus lagowskii, Dybowski Pseudorasbora parva, Ctenopharyngodon idellus, Carassius auratus and Cyprinus carpio was 20.75%, 44.90%, 10.42%, 98.41%, 0.77%, 61.29%, 74.51%, 12.5%, 8.57% and 21.21% respectively. The highest positive rate of 98.41% was for Pseudorasbora parva and the lowest rate of 0.77% was for Phoxinus lagowskii Dybowski; the average degree in per fish was 173.30±281.52, 538.65±610.31, 134.17±146.55, 581.50±1067.27, 32, 109.95±97.02, 1152.76±1181.73, 147.76±181.69, 111.78±119.89 and 629.41±317.96 respectively. The largest number of degree infection was Perccottus glehnidybowski (4833 metacercarias per fish), and the lowest was for Phoxinus lagowskii Dybowski (32 per fish). Infection rate of Clonorchis sinensis metacercariae in muscle, scales, skin, fins, gills was 100%, 2.86%, 20.30%, 13.99% and 6.32% respectively.There were important differences in the positive rate of MC across the different waters (χ~2=271.43,P<0.001), the fish in river is the most serious, the second is fish ponds, the lowest is the reservoir. There were important differences in the positive rate of MC across the different administrative region (χ~2=28.29,P<0.001), the fish of Heishan is the most serious, the second is Yixian and Beizhen , the lowest is the Jinzhou and Linhai. There were important differences in the positive rate of MC across the different season (χ~2=47.74,P<0.001), the most serious is summer and autumn, spring and winter are lower. There were important differences in the positive rate of MC across the different water layer (χ~2=64.92,P<0.001), the most serious is upper layer, the second is low layer, the middle is lowest. There were important differences in the positive rate of MC across the different feeding habits (χ~2=308.54 , P < 0.001), the most serious is omnivorous fish and carnivorous fish, herbivorous fish is lower.Conclusions1. The survey confirmed that Jinzhou is endemic area of clonorchiasis, where 10 species of freshwater fish are all infected by Clonorchis sinensis metacercaria, in which the wild Perccottus glehni and Pseudorasbora parva are the most serious.2. Clonorchis sinensis metacercaria is the most serious in muscle, therefore, the scales, skin and gills are relatively slight. 3. There were significantly differences among Clonorchis sinensis metacercaria infection rates in different waters, avrious administrative regions, seasons, water layers and feeding habits of freshwater fish.