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

We observed high proportions of positive samples among field rats (34.0%, 239/702) destined for human consumption and insectivorous bats in guano farms (74.8%, 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 (20.7%) to large markets (32.0%) and restaurants (55.6%), indicating amplification along the wildlife supply chain.

High proportions of positive samples were observed among insectivorous bats in guano farms (74.8%, 234/313) adjacent to human dwellings, indicating potential maintenance or reservoir dynamics at bat–human interfaces.

Coronaviruses were also detected in rodents on the majority of wildlife farms sampled (60.7%, 17/28). These coronaviruses were found in the Malayan porcupines (6.0%, 20/331) and bamboo rats (6.3%, 6/96) that are raised on wildlife farms for human consumption as food.

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.

High proportions of positive samples were observed among field rats (34.0%, 239/702) destined for human consumption, with coronavirus RNA detection increasing along the supply chain from traders to markets to restaurants in southern Viet Nam.

Insectivorous bats in guano farms (74.8%, 234/313) adjacent to human dwellings were also coronavirus-positive.

Coronaviruses were also detected in rodents on the majority of wildlife farms sampled (60.7%, 17/28). These coronaviruses were found in Malayan porcupines (6.0%, 20/331) and bamboo rats (6.3%, 6/96) raised on wildlife farms for human consumption.

Coronaviruses were found in bamboo rats (6.3%, 6/96) raised on wildlife farms for human consumption.

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.

We used consensus Polymerase Chain Reactions to detect coronavirus sequences... We identified six known coronaviruses in bats and rodents, clustered in three Coronaviridae genera, including the Alpha-, Beta-, and Gammacoronaviruses.

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.