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Pet Protection

Furry friends might be immunity boosters against MRSA.

Story by Salma Warshanna-Sparklin • Photography by Goja1/iStock • Illustration by Meriel Jane Waissman/iStock

Owning a pet means sharing everything from beds to bacteria. Don’t grimace: “The human immune system could actually benefit,” says veterinarian Meghan Davis, PhD ’12, MPH ’08, one of the few scientists in the U.S. studying this give-and-take, particularly with regard to methicillin-resistant Staphylococcus aureus (MRSA).

Community-associated MRSA spreads in gyms, schools and other places where people congregate, driving the rising epidemic of human-to-human transmission in the U.S. for the last 20 years. Researchers have blamed furry friends for helping MRSA colonize and infect humans.

“While pets can be MRSA vectors, they often get it from people first,” says Davis, assistant professor in Environmental Health Sciences.

Her latest findings from the Pets and Environmental Transmission of Staphylococci (PETS) study suggest that over time, pets contribute microbial diversity to the household, and this actually benefits owners. As to why, Davis isn’t sure yet. “So far, research in both people and animals appears to support that higher diversity is good,” she explains. “Lower diversity systems are more fragile, more likely to succumb if threatened by a disruption like a pathogen.”

In fact, having two or more pets was associated with a protective effect against MRSA colonization, her research shows.

Based on the data, household surfaces harbored more MRSA than family pets and posed a bigger transmission threat. Among pet-owning MRSA patients, only 15 percent of them had MRSA-positive animals at home. A whopping 70 percent had the bacterium on household surfaces.

Davis’s animal-loving bottom line: “We should definitely keep our pets—and keep them healthy—so they can contribute to the good health and well-being of our families.” 

Well Vetted


Well Vetted

As an environmental microbiologist, Meghan Davis studies the interface of bacteria and hosts to reduce disease in humans and animals. In between research, lectures, grading and conferences, she also mentors fellow veterinarians who are Bloomberg School MPH students. Davis—whose former students work for the Epidemic Intelligence Service at the CDC and the Center for Veterinary Medicine at the FDA—is enthused about the class of 2016 vets: “We’ve got a bumper crop this year!”

  • Caitlin Cotter, Wisconsin, U.S.
    Interests: Emerging infectious diseases and tropical medicine
  • Kathryn Dalton, Pennsylvania, U.S.
    Interests: Food safety and infectious disease management
  • Camille Effler, New Mexico, U.S.
    Interests: Food insecurity, water scarcity and sustainable agriculture
  • Matthew Ferreira, New Jersey, U.S.
    Interests: Relationships between human, animal and environmental health
  • Ricardo Millan, Bogotá, Colombia
    Interests: One Health, policy and infectious diseases 
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