New York City rats can catch the coronavirus that causes Covid-19, study finds

CNN

New research has revealed that Covid-19 can be transmitted to millions of Norway rats living in New York. Reports of the virus spreading to humans from other animals are rare.

Covid-19 has been found in pets such as cats, dogs, and hamsters, as well as zoo animals like big cats, primates, and hippos, farmed mink, and wildlife such deer and anteaters. The study was published in the American Academy of Microbiology journal mBio on Thursday. It involved the capture of 79 rats from three Brooklyn locations in fall 2021 to test for SARS-CoV-2 exposure.

In a news release, Dr. Tom DeLiberto (study co-author and SARS-CoV-2 coordinator at the US Department of Agriculture’s Animal and Plant Health Inspection Service) stated that most rats were caught in Brooklyn's city parks.

Thirteen (16%) of the 79 rats tested positive for the virus in IgG and IgM antibodies, suggesting an earlier infection with SARS-2.

Researchers note that a number of studies have shown that SARS-CoV-2 fragments have been found in sewage systems. They also suggest that SARS-CoV-2 outbreaks in human populations coincide with the presence of SARS-2 genes in sewage systems. However, there is no evidence that SARS-CoV-2 viruses found in sewage water are pathogenic, which suggests that rats may have been exposed via airborne transmission. Indirect transmission from unknown fomites or living in close proximity to humans, e.g. contaminated food waste.

The study found that two rats were positive for viral RNA and had positive blood tests. This suggests that animals previously exposed to seropositive bacteria may still be susceptible to contracting or shedding SARS-Co-V-2.

Genomic analysis showed that the virus that infected the rats was associated with the B lineage strain, which was predominant in the city during the Covid-19 pandemic.

The researchers conducted a virus challenge study to find out if the Alpha, Delta, and Omicron coronavirus variants could infect laboratory rats.

While other research has shown that rats from Hong Kong might have been exposed to coronavirus, this new release is believed to be the first to demonstrate that the variants can infect urban rats. Dr. Henry Wan was the principal investigator and director of Center for Influenza and Emerging Infectious Diseases (University of Missouri).

Wan states that the findings demonstrate the need to continue monitoring rat populations for new strains of virus. He also says that it is important to keep improving our knowledge so that both animal and human health can be protected.

The cases of humans spreading the virus from animals to animals are well documented. However, it is rare for infected mammals to spread the virus to humans by close contact, according to the US Centers for Disease Control and Prevention. The agency states that there is no evidence animals play any role in spreading the virus.

These findings will not change the behavior of people, and humans are still more likely to contract Covid-19 from others than animals, according to Dr. J. Scott Weese of the Centre for Public Health and Zoonoses of the University of Guelph, Canada. He was not part of the new research.

The study, however, is a reminder that the virus continues its spread, he stated.

"This study, I believe, just reinforced that we did a great job of passing it along to other species and they may still be maintaining it. This is what we will need to examine over time: Does it really stay in the rat and does it change over the time?

Weese stated that wild rats should be avoided in the interim. You can get many things from them. Just add [Covid-19] on to the list.

The USA was experiencing a downslope of the Delta wave when the Norway rats were collected in autumn 2021. There were more than 1,000,000 Covid-19 cases per week in September, and more than 500,000 in November, according to CDC data.