New York City study shows mice carry previously unseen pathogens

Sprawling cities aren’t exactly known for being the most sanitary of places. Huge populations plus small spaces equal lots and lots of trash. That said, human beings aren’t the only vehicles for dirt and disease in urban areas.

Epidemiologists at Columbia University conducted a yearlong study of house mice in New York City, and found that many of these rodents are laden with serious bacteria and viruses — including previously unseen variants.

Researchers collected over 400 mice, mainly from garbage disposal areas, from seven residential buildings in four of the city’s boroughs. (Five bonus mice were caught in food prep areas of a commercial building, and one came from somebody’s private apartment.)

The researchers analyzed the bacteria genomes from the captured mice’s droppings and identified 235 genera and 149 species of bacteria. These included many of the most common foodborne illnesses-causing bacteria: E. coli and Salmonella. The researchers also found evidence of genes associated with antibiotic resistance.

“Mouse droppings may contain harmful bacteria that are difficult to treat with common antibiotics,” Dr. W. Ian Lipkin, the study’s lead author, told CNN.

When they conducted a similar study of the viruses found in the mouse droppings, the researchers identified 36 viruses — six of which were entirely new to them. Fortunately, none were known to infect humans, but they can infect other animals, like dogs, chickens and pigs.

House mouse danger

The concern with mice is that, unlike rats (usually), mice aren’t uncommon in the home, meaning the diseases they carry might easily infect unwitting human neighbors. City residents are advised to keep an eye out for evidence of mouse activity in their homes.

“Mice are more worrisome because they live indoors and are more likely to contaminate our environment,” said Lipkin. “Contaminated areas should be thoroughly cleaned, and contaminated food should be discarded.”

Mice from the Big Apple aren’t the only ones that carry pathogens. Similar studies in other urban areas would likely yield similar results, experts say.

It’s still unclear how often, and how directly, mice might be spreading diseases to humans.

“The next step is to determine whether outbreaks of infection with bacteria can be traced back to exposure to mice,” Lipkin said.

Neogen develops a number of rodenticides and bait stations for effective mouse control in many settings.

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