NYC rats now carrying COVID-19, study reveals

WASHINGTON — New York City's rat problem may be even worse than anyone thinks. It turns out the filthy rodents can carry COVID-19, a new study warns. Researchers are revealing that rats are susceptible to infection from the Alpha, Delta, and Omicron variants.

Previous studies have discovered rats in Hong Kong and Belgium carrying the virus as they roamed the streets — possibly coming into contact with pedestrians. Now, scientists have evidence that rats in the sewer systems and streets of New York City are also carrying the virus.

Biologists collected samples from 79 rats in the Big Apple. After running various tests, they found that 13, or just under 17 percent, tested positive for COVID-19.

“Our findings highlight the need for further monitoring of SARS-CoV-2 in rat populations for potential secondary zoonotic transmission to humans,” says study principal investigator Henry Wan, Ph.D., Professor and Director of the Center for Influenza and Emerging Infectious Diseases at the University of Missouri, in a media release.

“Overall, our work in this space shows that animals can play a role in pandemics that impact humans, and it’s important that we continue to increase our understanding so we can protect both human and animal health.”

Rats are a widespread problem in urban communities throughout the United States. In New York City alone, there are approximately eight million wild rats who can easily interact with humans. The city's mayor, Eric Adams, was even fined for a rodent infestation in his building!

This is the first evidence of U.S. rats carrying COVID variants

“In Fall of 2021, U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) sampled Norway rats (Rattus norvegicus) in New York City to look for evidence of SARS-CoV-2 infection,” reports study co-author Tom DeLiberto, D.V.M., Ph.D., SARS-CoV-2 Coordinator at USDA APHIS Wildlife Services.

“Two trapping efforts were conducted during September and November with permission from the NYC Department of Parks and Recreation in and around locations surrounding wastewater systems. Most of the rats were trapped in city parks within Brooklyn, although some were captured near buildings outside of park boundaries.”

“To the best of our knowledge, this is one of the first studies to show SARS-CoV-2 variants can cause infections in the wild rat populations in a major U.S. urban area,” Dr. Wan adds.

The rats exposed to SARS-CoV-2 showed a possible link to the viruses that were circulating in humans during the early stages of the pandemic. The team conducted a virus challenge study, revealing that Alpha, Delta, and Omicron variants can all cause infections in rats. There was a high virus replication level in the upper and lower respiratory tracts and in immune responses, though susceptibility to infection depended on the COVID variant.

“Our findings highlight the need for further monitoring of SARS-CoV-2 in rat populations to determine if the virus is circulating in the animals and evolving into new strains that could pose a risk to humans,” Dr. Wan concludes. “SARS-CoV-2 virus presents a typical one-health challenge which requires collaborative, multisectoral and transdisciplinary approaches to fully understand such challenges.”

The study is published in the American Society for Microbiology journal mBio.

South West News Service writer Alice Clifford contributed to this report.