CDC Reports Five Norovirus Outbreaks on Cruise Ships in the Last Month
The main symptoms experienced by affected individuals are diarrhea, vomiting, and abdominal cramps, as reported by the agency.
In the past month, hundreds of cruise ship passengers fell ill due to stomach-related illnesses across five distinct incidents, according to an update from the U.S. Centers for Disease Control and Prevention (CDC).
As of December 31, the five outbreaks reported to the CDC resulted in 781 passengers and 109 crew members contracting illnesses. All outbreaks were attributed to norovirus, a virus known to cause stomach ailments characterized by symptoms such as vomiting and diarrhea.
The primary symptoms observed across all five outbreaks were diarrhea and vomiting, with abdominal cramps reported in both Queen Mary 2 cases.
According to the CDC, there were a total of 16 stomach illness outbreaks on cruise ships throughout 2024. In 13 of these outbreaks, norovirus was identified as the cause, while one instance each was attributed to E.coli and salmonella. The cause of one outbreak was listed as “unknown” by the CDC.
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The CDC indicates that it provides information about outbreaks on cruise ship voyages when at least 3% of the passengers and crew demonstrate symptoms of gastrointestinal illness, or in cases of “other outbreaks of public health importance,” whether the ships are sailing from U.S. or foreign ports.
“While norovirus is frequently responsible for gastrointestinal outbreaks on cruise ships, it is not always immediately clear which agent caused an outbreak during the initial investigation,” state CDC officials. “Identifying the causative agent of an outbreak can be a time-consuming process.”
Historical data reveals a maximum of 65 outbreaks reported during the same week in prior years.
Annually, the U.S. sees approximately 2,500 norovirus outbreaks, which can happen at any time of the year but are most prevalent from November to April.
Norovirus is responsible for around 900 deaths and 109,000 hospitalizations each year in the United States, primarily affecting adults aged 65 and older. It also leads to approximately 465,000 visits to emergency departments, largely among young children.
Health officials note that if a new strain of the virus emerges, there could be more than a 50% increase in norovirus illnesses. Norovirus outbreaks are common in health care facilities, long-term care centers, restaurants, child care facilities, schools, and on cruise ships.
Recognizing the link between norovirus outbreaks and cruise ships, the CDC points out that over 90% of “diarrheal disease outbreaks on cruise ships” can be attributed to the virus.
However, norovirus outbreaks on cruise ships represent “only a small fraction (1%) of all reported norovirus outbreaks,” according to the CDC. “Controlling norovirus on cruise ships can be particularly challenging due to close living conditions, communal dining areas, and high passenger turnover.”
While the majority of patients recover without medical assistance, some individuals—particularly older adults and young children—may need medical care due to dehydration resulting from vomiting and diarrhea.
The Associated Press contributed to this report.
