New York City’s rat population has caught researchers’ attention again, this time for a different reason. According to a study published in mBio, an open-access journal of the American Society for Microbiology, New York rats can be carriers of the COVID-19 virus. The study, conducted by researchers from Columbia University and the University of Missouri, concluded that wild rats in New York are susceptible to three COVID-19 variants, and infected rats have “ample opportunities” to interact with humans.
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The possibility of rats carrying the virus responsible for COVID-19 is not entirely new. During the Black Death, a pandemic that affected Europe from 1347-1351, it was widely believed that the virus was spread to humans through rodents. A large population of rodents were infected by plague-carrying fleas, which in turn directly infected a massive human population. Now, with COVID-19, the study’s principal investigator, Dr Henry Wan, says the new findings highlight the need for further examination to determine if the virus is circulating in rat populations and evolving into new strains that could pose a risk to humans.
Dr Henry Wan is the director of the Center for Influenza and Emerging Infectious Disease at the University of Missouri. He stated that the study was one of the first to show the possibility of COVID-19 variants causing infections in wild rats in a major US urban area. Studies in Hong Kong and Belgium found that rats were exposed to the virus behind COVID-19, but it is unclear which exact variant.
Animals can play a role in pandemics
The study was published on Thursday, virological studies and genomic sequencing was conducted by researchers on samples from 79 rats. The captured rats were mostly from parks in Brooklyn and with the NYC parks department’s permission, particularly in and around areas that were surrounded by wastewater systems. Of the 79 rats, 13 tested positive for COVID-19. Researchers then conducted a virus challenge study and found Alpha, Delta, and Omicron variant infections in Sprague Dawley rats.
“Overall, our research in this space shows that animals can play a role in pandemics that impact humans,” the authors of the study wrote, “and it’s important that we continue to improve our understanding so we can protect both human and animal health.”
The Center for Disease Control and Prevention (CDC) has determined that animal-to-human transmission of COVID-19 is rare, noting that in most cases, animals are infected by humans. However, Dr Wan said the new findings highlight the need for further examination before drawing any conclusions on this matter. There’s a potential risk of the virus in rat populations if it is circulating among the animals and evolving into new strains that could pose a threat to humans, said Dr Wan.
New York’s public health
Though humans are far more likely to catch COVID-19 from other humans than from animals, said Dr J. Scott Weese, director of the Centre for Public Health and Zoonoses at the University of Guelph in Canada, the study is a good reminder that the virus continues to spread. It is also a concern for the future that we need to approach things in a broader context, considering animal and human health altogether.
Other animals like dogs, cats, deer, primates, hippos, and anteaters are among those in which COVID-19 infections have been reported earlier. However, the focus has mostly been on domestic animals, and research on the virus’s transmission from wild animals to humans is still limited.
The study’s findings have prompted concerns over public health, particularly in a city like New York, which has an estimated rat population of eight million. Infected rats can interact with humans, making the possibility of human-to-rat transmission a real concern. As the study’s authors noted, it is crucial to continue research to protect both animal and human health.
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