14 November 2021

In case you missed it.

At the beginning of the COVID-19 pandemic scientists wondered if other species could catch the virus and transmit it back to humans. Fortunately, so far no COVID-infected animals have transmitted the virus back to us. However white-tailed deer easily catch COVID from humans and spread it deer-to-deer.

NPR reports that a study of deer in Iowa last year found that deer are very susceptible to COVID. During most of the year 30% of tested deer had COVID, but during hunting season with more human contact 80% of deer showed signs of infection. Deer also spread it easily among themselves so that the prevalence of COVID in deer is now 50 times that of humans.

Deer are lucky. COVID doesn’t make them sick and it doesn’t kill them. But the fact that the virus that causes COVID, SARS-COV-2, circulates so widely among a common North American mammal may come back to bite us.

If deer become a reservoir for SARS-COV-2 and eventually transmit it back to us or to our livestock or companion animals (dogs and cats), then it has a good chance of mutating into something more unpleasant. At the very least it will never disappear.

The fact that deer catch COVID should not surprise us. SARS-COV-2 jumped from bats to humans and then spread easily from human-to-human. Here are some other viruses that cross species.

• Influenza originates in aquatic birds (ducks), jumps from birds to domestic pigs, from pigs to humans, then human-to-human. Because the virus evolves so fast a new flu vaccine is needed every year.
• Measles evolved from rinderpest, a virus that infects cattle, which began infecting humans between 400 BC and 500 AD. Eventually the virus diverged from rinderpest in the 11th or 12th centuries.
• Humans mumps is closely related to bat mumps Orthorubulavirus. It probably crossed over from bats.
• Rubella or “German measles” is related to ruhugu, a bat virus.

As deer have shown, virus jumping is more common than we thought.

Read more or listen to the podcast at NPR: How SARS-CoV-2 in American deer could alter the course of the global pandemic.

(photo from Wikimedia Commons)