Investigation and research of Clonorchis sinensis metacercariae and Metorchis orientalis metacercariae infection in freshwater fishes in China from 2015 to 2017

Abstract

BackgroundClonorchiasis has been known for over 2300 years in China and it is considered as one of the most notorious food-borne parasitic diseases. In 2004, a total number of 15 million people were infected with Clonorchis sinensis around the world, in which more than 85% people lived in China. This was the first epidemical study about Clonorchis sinensis metacercariae and Metorchis orientalis metacercariae infection in freshwater fishes in seven endemic regions of China. MethodsA total number of 2909 samples were collected from year 2015–2017. The regions of epidemic area of C. sinensis and Metorchis orientalis included Jilin, Heilongjiang, Shanghai, Zhejiang, Anhui, Guangdong and Guangxi provinces of China. 16 fish species were examined. Encysted metacercariae of C. sinensis and Metorchis orientalis were examined with digestion technique. The chi-square test, the Fisher's exact test and the logistic regression were applied in this study. ResultsThe infection rate of C. sinensis metacercariae was 3.10% (90/2904) and that of Metorchis orientalis metacercariae was 1.20% (34/2831). The infected freshwater fishes were sold in different locations including fish pond, farm produce market, supermarket and restaurant. The infection rates of C. sinensis metacercariae and Metorchis orientalis metacercariae in Pseudorasbora parva were the highest up to 25.00% (17/68) and 14.93% (10/67), respectively. ConclusionsFish species was the major influence factor to the infection rates of C. sinensis metacercariae and Metorchis orientalis metacercariae.