Health officials warn that overseas travelers have been returning to the U.S. with a strain of Shigella bacteria that's resistant to antibiotics. There is no vaccine to prevent Shigellosis, so what can you do to avoid infection?

Here are steps recommended by the Centers for Disease Control and Prevention to avoid this diarrheal disease:

1. Carefully wash your hands with soap, especially before eating or handling food and after changing a diaper, especially if you are caring for a child who has Shigellosis.

2. Avoid swallowing water from ponds, lakes, or untreated swimming pools.

3. When traveling internationally, follow food and water precautions strictly and wash hands with soap frequently.

4. Avoid sexual activity with those suffering from symptoms of Shigellosis or who have just recovered from it.

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

The CDC released an advisory on April 2, acknowledging clusters of the illness from Massachusetts to California. It said 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.