Identification and genetic characterization of Contracaecum sp. (Nematoda: Anisakidae) from China

Contracaecum species are economically important fish-borne larval nematodes with zoonotic significance. In June 2019, more than one hundred piscivorous birds were died in its habitats close to the Wild Duck Lake, located in Yanqing, northwest of Beijing, China. Post-mortem examination of Black Night Herons (Nycticorax) revealed the presence of numerous anisakid nematodes in the proventriculus. Recovered nematodes were identified as Contracaecum sp. based on morphological description. Phylogenetic analysis of the mitochondrial (mt) genome and the ITS gene showed that sequences of Contracaecum sp. Beijing isolates were grouped into a new individual cluster. Furthermore, the parasite was successfully isolated from fresh dead birds, feces of piscivorous birds, and fish and prevalence ranged from 8.0% to 81.8%. Consequently, our study demonstrated the Contracaecum sp. infections in different sources from China, which might constitute a threat to wildlife, aquaculture, and public health. This article is protected by copyright. All rights reserved.