ATLANTA – International travelers are returning to the United States carrying more than luggage. The Atlanta-based Centers for Disease Control and Prevention reported that multidrug-resistant Shigellosis is being repeatedly introduced to the US by sick travelers, who later infect other individuals. 

A photo of drug-resistant Shigella bacteria

Drug-resistant Shigella

The CDC and its health partners made the discovery while researching a cluster of Shigella sonnei outbreaks that sickened 243 individuals in 32 states and Puerto Rico between May 2014 and February 2015. Nearly 90 percent of the cases tested were resistant to ciproflaxin, an antibiotic that is the first choice to treat Shigellosis, CDC reported.

“These outbreaks show a troubling trend in Shigella infections in the United States,” said CDC Director Tom Frieden, MD, MPH. “Drug-resistant infections are harder to treat and because Shigella spreads so easily between people, the potential for more — and larger — outbreaks is a real concern.

“We’re moving quickly to implement a national strategy to curb antibiotic resistance because we can’t take for granted that we’ll always have the drugs we need to fight common infections.”

The agency said Shigella already is resistant to ampicillin and trimethoprim/sulfamethoxazole. Meanwhile, Cipro-resistant Shigellai is spreading globally.

In December 2014 CDC spotted an increase in Shigella sonnei infections with an uncommon genetic fingerprint through the agency’s PulseNet lab network. Further testing revealed that the bacteria were resistant to Cipro. The cluster of illnesses found via PulseNet included 45 cases in Massachusetts; 25 cases in California; and 18 cases in Pennsylvania.

CDC said about half the cases with patient information were associated with international travel, mostly to the Dominican Republic and India. In San Francisco, another 95 cases — nine uncovered by PulseNet — involved homeless individuals or people living in single-room occupancy hotels, the agency said.

“The increase in drug-resistant Shigella makes it even more critical to prevent shigellosis from spreading,” said Anna Bowen, MD, MPH, a medical officer in CDC’s Waterborne Diseases Prevention Branch and lead author of the study. “Washing your hands with soap and water is important for everyone. Also, international travelers can protect themselves by choosing hot foods and drinking only from sealed containers.”

Shigella sickens an estimated 500,000 individuals per year. It spreads rapidly from person to person through contaminated food and recreational water. It can cause watery or bloody diarrhea, abdominal pain, fever, and malaise. Shigellosis can spread very quickly in specific groups such as children in childcare facilities and homeless people, as occurred in these outbreaks. CDC recommended improving access to toilets and soap and water for hand washing to help prevent Shigella transmission among the homeless.