The Centers for Disease Control and Prevention are investigating two seemingly separate outbreaks of Norovirus linked to U.S. cruise ships.
Cases have been linked to Princess Cruises' Sapphire Princess and Royal Caribbean International's Radiance of the Seas.
The CDC's Vessel Sanitation Program (VSP) is tracking the "very contagious" outbreaks following reports of passengers in distress.
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Approximately 67 out of 1,993 passengers on the Radiance of the Seas reported falling ill during its voyage from Tampa to Los Angeles between Apr. 8 and 22. An additional two crew members also reported illness.
The predominant symptoms reported from those affected by the Norovirus were diarrhea and vomiting.
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Approximately 94 of 2,532 passengers on the Sapphire Princess reported similar symptoms during its voyage from Los Angeles into the South Pacific that began Apr. 5 and is scheduled to conclude on May 7.
An additional 20 members of the 1,066 crew reported symptoms as well.
Fox Business reached out to both Princess Cruises and Royal Caribbean International for comment on the situation but did not receive a response.
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"Norovirus is a very contagious virus that causes vomiting and diarrhea. Anyone can get infected and sick with Norovirus," the CDC states on its website. "Norovirus is sometimes called the 'stomach flu' or 'stomach bug.' However, norovirus illness is not related to the flu, which is caused by influenza virus."
One of the biggest health risks posed by Norovirus infection is dehydration — the CDC recommends those infected drink plenty of liquids to aid recovering.
The CDC's Vessel Sanitation Program requires cruise lines to report and document cases of illness on their ships in order to facilitate coordinated responses in case of emergency.