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Coronavirus risk increases with exposure to wildlife destined for human consumption

Malayan porcupine (Hystrix brachyura) farm in Dong Nai province, November 2013.

A new publication co-authored by a Berkeley Public Health alumnus shows that the risk of contracting and transmitting coronavirus increases with exposure to farmed wildlife destined for human consumption.

The publication reports on research collected in 2013-2014 on the origins and spread of coronavirus in Vietnam. Released after almost seven years of generating and analyzing data and securing government approval for publication, the study explores the coronavirus risk in and around wildlife supply chains for human consumption.

This study was initiated in 2009 as a part of a United States Agency for International Development epidemiological project, PREDICT, created as an early pandemic warning system.

The study looks at coronaviruses in general, not specifically at SARS-CoV-2, the virus that causes COVID-19. However, researchers said that this study is helpful in determining the origin and emergence of a variety of coronaviruses, including SARS-CoV-2.

Researchers found a 34% rate of coronavirus among field rats intended for human consumption and an almost 75% rate among bats on guano farms located next to human dwellings. The odds of coronavirus detection increased for field rats sold in large markets and field rats sold and served in restaurants.

“Adverse conditions along the rat trade supply chain, such as those at restaurants and large markets, likely contribute to the high prevalence of coronavirus found in wild animals,” said study co-author Huong Nguyen, MPH ’19. “Further investigation into how to prevent these conditions as well as how to minimize direct human contact and exposure using protective equipment and control measures is imperative to reduce the risk.”

Researchers also found that within a majority of the wildlife farms they studied, more than 60% of rodents raised for human consumption—including Malayan porcupines and bamboo rats—carried coronavirus. Researchers identified six different known coronaviruses among bats and rodents in this study.

Nguyen joined the study in 2018 and wrote her capstone paper on the topic. She became interested in coronavirus as an emerging public health threat and also noticed the lack of research from Vietnam.

“This is an important paper because it shows the high risk of human exposure to coronaviruses in the food supply involving farmed wildlife. And that risk goes up as the rats move through the food supply chain,” said Peter Dailey, Infectious Diseases and Vaccinology professor at Berkeley Public Health. “Coronaviruses have high host plasticity, meaning they can move more easily from one species to another, which might enable recombination and selection of variants more likely to infect humans. Now is the time to move from surveillance and predicting spillover to changes in policy and prevention.”

Read the research paper at PLOS One.