July 23, 2019

You may want to think twice before sharing a bite of spare food with animals you encounter in public places. That is, unless you’re willing to risk a staph infection.

Staphylococcus aureus (S. aureus) is a bacterium that causes a wide range of infections, such as skin and soft tissue infections (SSTI), bone, joint and implant infections, pneumonia and more. Both penicillin and methicillin have been used to fight S. aureus, but strains resistant to all types of treatment have continued to emerge. Now, methicillin-resistant S. aureus (MRSA) has become a serious international problem.

In a hospital setting, MRSA can be deadly; in fact, it caused 11,000 deaths in hospitals in the U.S. in 2017. And while practices to reduce MRSA cases in hospital populations are improving, the bacterium continues to thrive in the wild in certain geographic areas. It is of particular concern in places where large numbers of humans and animals interact, including popular tourist destinations.

In a recent study, researchers at the Washington National Primate Research Center (WaNPRC) at the University of Washington (UW) along with their Nepali colleagues sampled 59 rhesus monkeys within Nepal. Those monkeys have close interactions with humans, usually at temple sites, where people offer the animals food. The researchers used a non-invasive method to collect saliva samples from the monkeys with subsequent processing at a microbiology laboratory in Nepal.

The findings were astounding. Of the macaque samples tested, 6.8% were positive for MRSA, and three of four MRSA isolates were identified as ST22 SCCmec IV. The ST22 SCCmec IV strain is normally considered a human strain, and this study suggests that humans in Nepal are sharing their strains with the wild macaque populations.

The researchers further reiterate a warning that is becoming all too well known, that even minimal contact with wild animals, especially contact with saliva or an animal bite can present significant health risks to humans.

“Some types of MRSA are found all over the world and are pandemic strains,” said lead study author Marilyn C. Roberts, PhD. “The importance should be stressed in respect to these populations of wild animals. Even feeding chipmunks or ducks human food is not a good thing. They can pick up what we have, and we can pick up what they have. Some of the infectious agents wildlife carry can be deadly.”

“Given the results of our work in Nepal, we are now extending the MRSA investigation to primates in Thailand. These efforts are part of our larger collaborative program promoting the healthy coexistence between humans and primates,” added co-author and field researcher Randall C. Kyes, PhD.


Photo Credit: Randall C. Kyes, PhD

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