Deer carry variants of COVID that are no longer seen in humans

By Cara Murez

health day reporter

FRIDAY, Feb. 3, 2023 (HealthDay News) — Although the Alpha, Gamma and Delta variants of COVID-19 are no longer circulating among humans, they continue to spread among white-tailed deer.

Animals are the most abundant large mammal in North America. Scientists don’t know if deer could serve as a long-term reservoir for these outdated variants.

In a new study, researchers at Cornell University, in Ithaca, NY, collected 5,700 lymph node samples from deer from 2020 to 2022 in the state, comparing the genomic sequences of variants found in deer with sequences from the same variants taken from humans across New York.

Investigators found that the viruses had mutated in deer, suggesting the variants had likely been circulating in the animals for many months.

“One of the most striking findings of this study was the detection of the co-circulation of three variants of concern – Alpha, Gamma and Delta – in this wild animal population,” said Diego Diel, associate professor of medicine Populations and Diagnostic Sciences at Cornell. , said in a university press release.

When the researchers detected the Alpha and Gamma variants in deer, there was no evidence that these viral strains were still circulating in humans, and they hadn’t been for four to six months.

“When we performed sequence comparisons between these viruses recovered from white-tailed deer with the human sequences, we observed a significant number of mutations in the virus genome,” Diel said.

Some of the viruses had up to 80 mutations compared to human sequences. This provided further evidence that the viruses had likely been circulating in deer for some time. The virus may have adapted to deer, possibly making it more transmissible between them.

According to the study, deer have been infected with COVID-19 through continuous contact with humans, possibly through hunting, wildlife rehabilitation, feeding wild animals, or through sewage or springs. of water.

“A virus that emerged in humans in Asia, most likely after an animal reservoir spillover event into humans, has apparently, or potentially, found a new wildlife reservoir in North America,” Diel said. .

A 2022 study by Diel and others found that in five states surveyed in 2021, the COVID-19 virus was found in up to 40% of white-tailed deer. There are 30 million animals in the United States.

The researchers said further studies were needed to confirm whether these variants would disappear in deer over time or spread to other wildlife, such as predators.

“Because of the evidence obtained in our study, it is very important to continue to monitor the virus in these animal populations to truly understand and track changes that could lead [to] or favor the return on humans and other wild animals,” Diel said.

The results of the study were published on January 31 in the Proceedings of the National Academy of Sciences.

More information

The US Centers for Disease Control and Prevention has more on COVID-19 in animals.

SOURCE: Cornell University, press release, January 31, 2023