Surveillance of enteric pathogens in imported seafood and environmental surfaces in five seafood markets before the outbreak of COVID-19

Fu, S.; Wang, W.; Wang, Q.; He, F.; Hao, J.; Pang, B.

To monitor the presence of enteric pathogens in imported seafood, a total of 140 seafood samples imported from eight overseas countries were collected from Beijing, Dalian, Shanghai, Guangzhou, and Wuhan seafood markets from June to November 2019. Additionally, 116 viral, environmental swab samples were also collected from the Wuhan and Guangzhou seafood markets. Five typical enteric bacterial pathogens (Aeromonas spp., Shigella spp., Salmonella spp., Vibrio spp., and Listeria monocytogenes) and four viruses (Rotavirus, Norovirus, Astrovirus, and Sapovirus) were detected positive. Results showed that eight Vibrio parahaemolyticus isolates appeared in seafood imported to Dalian, Wuhan, Shanghai, Guangzhou, and Beijing. In contrast, Vibrio fluvialis and Aeromonas were isolated in another two samples. Norovirus was detected in one oyster sample imported from France and environmental surface in Guangzhou. The remaining pathogens were negative in all the samples being tested. With 120 V. parahaemolyticus isolates from the above countries, the genomic analysis revealed that sequence type ST1152 isolates imported from Canada were clustered with two V. parahaemolyticus isolates from Canada. This study presented the first microbiological analysis of the Wuhan seafood market before the outbreak of COVID-19, which demonstrated that supervision should be strengthened to prevent enteric pathogens via imported seafood. © 2021