Long-distance transmission of pathogenic Vibrio species by migratory waterbirds: a potential threat to the public health

Songzhe Fu,Ruijun Li,Shigen Ye,Ying Liu,Yi Wang,Jingwei Hao,Qian Yang,Ruiting Lan

doi:10.1038/s41598-019-52791-5

Songzhe Fu, Ruijun Li + Show 6 more

Open Access

https://doi.org/10.1038/s41598-019-52791-5

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Abstract

A potential mechanism for the global distribution of waterborne pathogens is through carriage by the migratory waterbirds. However, this mode of transmission has yet been confirmed epidemiologically. Here, we conducted whole genome sequencing of Vibrio spp. collected from waterbirds, sediments, and mollusks in the estuary of the Liaohe River in China to investigate this transmission mode. We found that a V. parahaemolyticus strain isolated from a waterbird was clonally related to the other V. parahaemolyticus strains obtained from the sediments and mollusks, and three V. mimicus strains isolated from bird feces were genomically related to those found in the mollusks and upstream groundwater, suggesting that the bird-carried Vibrio strains were acquired through the direct predation of the local mollusks. Surprisingly, two bird-carried V. parahaemolyticus strains belonging to the same clone were identified in Panjin and Shanghai, which are over 1,150 km apart, and another two were found at two locations 50 km apart, further supporting that waterbirds are capable of carrying and disseminating these pathogens over long distances. Our results provide the first evidence of direct transmission from mollusks to waterbirds and confirm that waterbirds act as disseminating vehicles of waterborne pathogens. Effective surveillance of migratory waterbirds along their routes will be valuable for predicting future epidemics of infectious diseases.

Highlights

A potential mechanism for the global distribution of waterborne pathogens is through carriage by the migratory waterbirds
A follow-up investigation showed that several tons of wastewater from fish ponds were discharged into the river after the clean-up of the outbreak-related ponds, which might have resulted in the transmission of the pathogens from Anshan into the estuary downstream
It has recently been recognized that the dissemination of antibiotic resistance can be mediated by migratory birds[14], the potential of migratory birds to disseminate Vibrio species had been neglected by the scientific community for more than three decades, until 2008 in a study by Halpern et al (2008) which suggested that the dispersal of Vibrio species by waterbird may be attributable to their direct predation of chironomids and copepods[15]

Summary

Introduction

A potential mechanism for the global distribution of waterborne pathogens is through carriage by the migratory waterbirds. This mode of transmission has yet been confirmed epidemiologically. We conducted whole genome sequencing of Vibrio spp. collected from waterbirds, sediments, and mollusks in the estuary of the Liaohe River in China to investigate this transmission mode. Laviad-Shitrit et al.[11] found that both Vibrio species and Aeromonas species were abundant in many types of birds in Israel, suggesting that migratory waterbirds are potential disseminators of waterborne pathogens. We investigated the evolutionary origins of the Vibrio species carried by waterbirds using whole-genome sequencing

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