Uh-Oh: NYC Mice May Be More Dangerous Than Rats

(CN) — New York City house mice carry bacteria that can give humans a stomach flu that ranges from mild to life-threatening — and may be antibiotic-resistant — a new study finds.

The report published Tuesday in the journal mBio was based on 416 mice collected at residential properties in seven sites over a year. Researchers performed genetic analyses of the rodents’ droppings, which revealed that they carry multiple stomach flu-causing bacteria, including salmonella, Clostridium difficile, E. coli and shigella.

“From tiny studios to penthouse suites, New York City apartments are continually invaded by house mice,” according to lead author Simon H. Williams, a research scientist at Columbia University’s Center for Infection and Immunity (CII).

He added: “Our study raises the possibility that serious infections — including those resistant to antibiotics — may be passed from these mice to humans, although further research is needed to understand how often this happens, if at all.”

The team said it is well known that salmonella infections can result from people consuming food contaminated with animal waste, such as mouse feces. Though typically transmitted in health care settings, C. difficile infections can also be spread by mice that carry the pathogens.

There are 1.4 million reported cases of salmonella infection in the United States each year, leading to 15,000 hospitalizations and 400 deaths.

A corresponding report also published in mBio examines the array of viruses found in the mouse droppings. The researchers identified 36 viruses, including six new ones, though none are known to infect humans. However, the pathogens’ genetic sequences match viruses that infect pigs, chickens and dogs, which suggests that some of them could have been transferred from other species.

Mice in the Chelsea neighborhood of New York were heavier than mice at other sites and carried more viruses.

A previous study on New York rats by CII researchers revealed several of the same pathogens, such as salmonella, E. coli and C. difficile.

“New Yorkers tend to focus on rats because they are larger and we see them scurrying around in streets or subways; however, from a public health vantage point, mice are more worrisome because they live indoors and are more likely to contaminate our environment, even if we don’t see them,” said CII director W. Ian Lipkin, senior author of both papers.

The research was supported by grants from the National Institutes of Health and the Alfred P. Sloan Foundation.

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