No evidence that livestock can transmit COVID-19 to humans

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Veterinary experts assert that there is no indication that livestock can be carriers of COVID-19 and be a source of infection to people.

A growing chorus of veterinary experts is pointing out that while multiple species-specific coronaviruses affect livestock and poultry, there is no evidence that the currently circulating novel SARS-CoV-2 coronavirus, which causes COVID-19, causes disease in livestock and poultry.

“Producers are well aware that there is a (different strain of) coronavirus that is associated with neo-natal diarrhea, and there’s another one that we think is now associated with cattle respiratory disease,” said Gregg Hanzlicek, director of the production animal field investigations unit in the Kansas State University Veterinary Diagnostic Laboratory.

“I want to make it perfectly clear that our cattle coronavirus has no relationship to the coronavirus that is currently circulating in humans. These coronaviruses are very species-specific. There is absolutely no indication that livestock can be carriers of COVID-19 and be a source of infection to humans, either through carrying it on their skin or their hair or anywhere else,” Hanzlicek said.

“Milk, eggs, beef, pork ... whatever proteins that are produced by livestock are absolutely safe to eat. People do not have to worry about those products carrying COVID-19 to the population,” he added.

Coronavirus infections are nothing new to the poultry industry. For as long as anyone can remember, infectious bronchitis (IB) viruses have caused widespread losses in poultry flocks worldwide.

Dr. Mark Jackwood, a molecular virologist and infectious bronchitis specialist who works at the University of Georgia’s Poultry Diagnostic & Research Center and heads the department of population health in the university's College of Veterinary Medicine, explained that the coronavirus that affects poultry and causes respiratory disease in chickens is in the avian gammacoronavirus group, which does not infect or cause disease in people.

Jackwood noted that the virus that causes COVID-19 is in the betacoronavirus group along with SARS-CoV and MERS-CoV.

“It was previously shown that SARS-CoV does not infect or cause disease in poultry,” Jackwood said in a statement jointly issued by the University of Georgia and the American Association of Avian Pathologists.

Because the COVID-19 virus belongs to the same group as SARS-CoV and uses the same ACE-2 host cell receptor, he said it was “highly unlikely” that the COVID-19 virus would infect or cause disease in poultry.

Scott Kenney, a coronavirus researcher at The Ohio State University College of Food, Agricultural & Environmental Sciences, noted that “viruses are constantly sampling and evolving, trying to find other hosts.”

When viruses infect an animal, they produce billions of copies of themselves, Kenney said, adding that some of the copies tend to be slightly changed from the original virus. While most of these irregular copies die, occasionally one has a change that is beneficial for the virus, such as altering its ability to infect a different species, Kenney said.

“If the new species is exposed to this altered virus, it can now make many more copies of itself and potentially infect a whole new species,” he said.

So far, the only research on COVID-19 and animals involves studies in China that showed two dogs tested positive for COVID-19, but neither of the infected dogs had symptoms of the virus, and researchers in those studies do not believe they transmitted the disease to any other animals or people, Kenney said.

Among farm animals, pigs seem to be the most susceptible to coronaviruses, able to contract up to six different pig-specific coronaviruses, Kenney said.

“I’m not sure anyone really knows why,” he said. “Outside of bats, pigs and humans seem to be infected by the largest numbers of different coronaviruses.”

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