Nearly one in 10 patients admitted to a New York hospital without symptoms of Clostridioides difficile infection turned out to be carriers of the deadly bug, a new study has found. 

Researchers at Montefiore Health System tested 220 patients who showed no symptoms of C. diff infection at the start of a nine-month study period. Perirectal swabs were completed within 24 hours of admission, and patients were followed for six months. Twenty-one patients were identified as carriers.

Within six months, 38% of those carriers had symptomatic C. diff infection, compared to 2% of the non-carriers.

The findings suggest that C. diff infections originate outside healthcare settings more often than previously thought, said Sarah Baron, M.D., of Albert Einstein College of Medicine, New York City. Efforts to reduce the infections typically focus on patients with symptoms. But there is likely a large pool of people carrying the bacterium who are at risk of passing it to others and/or developing an infection themselves, she said.

“These findings might mean that we can predict who will develop C. diff and try to stop it before it starts,” Baron concluded.

The study was published Wednesday in Infection Control & Hospital Epidemiology.