A stubborn strain of an intestinal illness is making noise in several states, including New Jersey.

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Travelers from overseas have been returning to the U.S. with a strain of Shigella bacteria that's resistant to its primary antibiotic, health officials claim.

Outbreaks of the diarrheal illness are common, but normally, cases would be easily treated with the drug known as ciprofloxacin.

Besides diarrhea, symptoms can include fever, nausea and vomiting.

The Centers for Disease Control and Prevention released an advisory on April 2, acknowledging clusters of the illness from Massachusetts to California. According to the CDC, the drug-resistant strain sickened more than 240 people in 32 states and Puerto Rico between May 2014 and Feb. 2015.

"The majority have traveled overseas to a few countries in the Caribbean and to India and a couple of others, and they all acquired the illness either soon after the travel or during the travel," said CDC epidemiologist Eric Mintz.

Mintz said shigellosis has the ability to develop in the U.S. on its own, but lesser sanitation and hand-washing practices in other nations result in more cases internationally.

Dr. Ed Lifshitz of the Communicable Disease Service with the New Jersey Department of Health said the state knows of three cases associated with the outbreak, but "without a doubt," there are more cases that have gone unreported.

"This is an ongoing problem, not just with Shigella, but with other bacteria in general," Lifshitz said. "We're seeing increasing resistance in many different bacteria."

"Good hand hygiene" is considered the key to preventing the spread of shigellosis, Lifshitz said, primarily before eating and after using the bathroom.

Shigella is considered very contagious, according to the CDC website, but this strain should not result in any fatalities unless old age or underlying medical conditions are part of the equation.