Abstracts: Coronavirus testing indicates transmission risk increases along wildlife supply chains for human consumption in Viet Nam, 2013-2014

Outbreaks of emerging coronaviruses in the past two decades and the current pandemic of a novel coronavirus (SARS-CoV-2) that emerged in China highlight the importance of this viral family as a zoonotic public health threat. To gain a better understanding of coronavirus presence and diversity in wildlife at wildlife-human interfaces in three southern provinces in Viet Nam 2013–2014, we used consensus Polymerase Chain Reactions to detect coronavirus sequences.

In comparison to previous studies, we observed high proportions of positive samples among field rats (34.0 per cent, 239/702) destined for human consumption and insectivorous bats in guano farms (74.8 per cent, 234/313) adjacent to human dwellings. Most notably among field rats, the odds of coronavirus RNA detection significantly increased along the supply chain from field rats sold by traders (reference group; 20.7 per cent positivity, 39/188) by a factor of 2.2 for field rats sold in large markets (32.0 per cent, 116/363) and 10.0 for field rats sold and served in restaurants (55.6 per cent, 84/151).

Coronaviruses were also detected in rodents on the majority of wildlife farms sampled (60.7 per cent, 17/28). These coronaviruses were found in the Malayan porcupines (6.0 per cent, 20/331) and bamboo rats (6.3 per cent, 6/96) that are raised on wildlife farms for human consumption as food. We identified six known coronaviruses in bats and rodents, clustered in three Coronaviridae genera, including the Alpha-, Beta-, and Gammacoronaviruses.

Our analysis also suggested either mixing of animal excreta in the environment or interspecies transmission of coronaviruses, as both bat and avian coronaviruses were detected in rodent feces on wildlife farms. The mixing of multiple coronaviruses, and their apparent amplification along the wildlife supply chain into restaurants, suggests maximal risk for end consumers and likely underpins the mechanisms of zoonotic spillover to people.

The study is from the Wildlife Conservation Society, Viet Nam Country Program, Ha Noi, Viet Nam; Department of Animal Health, Ministry of Agricultural and Rural Development of Viet Nam, Ha Noi, Viet Nam; Wildlife Conservation Society, Health Program, Bronx, New York, USA; EcoHealth Alliance, New York, New York, USA; Regional Animal Health Office No. 6, Ho Chi Minh City, Viet Nam; Faculty of Veterinary Medicine, Viet Nam National University of Agriculture, Ha Noi, Viet Nam; One Health Institute, School of Veterinary Medicine, University of California, Davis, California, USA, and Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria.

Huong NQ, Nga NTT, Long NV, et al. PLoS ONE 2020; 15(8): e0237129.

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