According to a preprint study, researchers in Canada may have found a potential case of deer to human COVID-19 transmission.
Viruses often jump from animals to humans and vice versa. While some are just isolated incidents, others can result in a spillover event. Moreover, since viruses undergo mutations in animal reservoirs, there is always a risk of the mutated strains causing more severe infections in humans. In the past, scientists have reported several incidences of animals infected with SARS-CoV-2. Including a case from last year of canine coronavirus causing infection in humans. Now, a preprint study has found evidence of a probable deer to human COVID-19 transmission.
Last year, Canadian researchers analyzed nasal and lymph node tissue samples from 300 white-tailed deers in Southwestern and Eastern Ontario. Only 17 tested positive for SARS-CoV-2. However, genomic sequencing revealed a ‘highly divergent’ strain of the virus within these samples. According to the preprint study, the strain had 76 mutations compared to the original Wuhan strain. Moreover, 23 mutations of these mutations had never before been seen in deers.
Later, when the researchers compared the deers’ viral genomes to those of humans in the area, they found a person infected with a similar strain. The person belonged to Southwestern Ontario and reported close contact with deers. However, it is unclear how the virus could have transmitted from deer to humans. Neither is it confirmed whether an intermediate host was involved, or the person received the virus as direct contact with a deer.
What’s the Concern?
Although this is an isolated case, the single case raises multiple concerns. Firstly, deers can silently harbour infections and likely cause outbreaks in humans. Secondly, the virus can undergo mutations in the deer, leading to new variants of the virus.
According to the study authors, this is the first case of deer to human COVID-19 transmission. However, there is no evidence of other human cases with the particular lineage. For now, Canada’s public health agency is urging caution when feeding or in close contact with deers.
Pickering, Bradley, et al. “Highly Divergent White-Tailed Deer Sars-COV-2 with Potential Deer-to-Human Transmission.” 2022, doi:10.1101/2022.02.22.481551.