(CNN) – More than 130 cruise ship passengers reported suffering from a gastrointestinal disease after setting sail from Los Angeles on July 4. The cause of the outbreak has not been determined.
The US Centers for Disease Control and Prevention says 134 passengers on Royal Caribbean’s Navigator of the Seas — or 3.4 percent of the cruise’s total passenger list of 3,900 people — reported feeling ill. Seven members of the crew were also affected, out of a total of 1,266 staff members.
The outbreak was reported to the CDC’s Vessel Sanitation Program (VSP) on July 11 when the weeklong Royal Caribbean cruise returned to Los Angeles to dock after the trip was over.
According to records compiled by the VSP, there have been 18 outbreaks of gastrointestinal illness on cruise ships under the program’s jurisdiction so far this year, mainly related to Norovirus.
That’s the same number of outbreaks reported all of last year, according to incidents logged by the CDC.
While it’s unclear what caused the outbreak on the Royal Caribbean ship, passengers experienced diarrhea, vomiting and abdominal cramps, the CDC said in a post this week about the Navigator of the Seas outbreak.
In April, about 250 passengers on the Queen Mary 2 reported coming down with the highly contagious norovirus.
That disease has a reputation as “the cruise ship virus,” infectious disease expert Dr. William Schaffner, of Vanderbilt University Medical Center, told CNN Travel earlier this year.
That’s because it spreads easily, and anyone in close quarters — like cruise ships — is extra susceptible. Such outbreaks also frequently occur in schools and jails — wherever large groups of people gather in tight spaces.
But the CDC hasn’t determined yet if the culprit on the Navigator of the Seas was norovirus.
“The health and safety of our guests, crew, and the communities we visit are our top priority,” a Royal Caribbean Group spokesperson told CNN Travel. “To maintain an environment that supports the highest levels of health and safety onboard our ships, we implement rigorous cleaning procedures, many of which far exceed public health guidelines.”
The CDC says Royal Caribbean reported boosting its cleaning and disinfection procedures and also collected specimens from infected passengers, after isolating anyone who was ill.
CNN wellness expert Dr. Leana Wen said that while infectious diseases can be “very unpleasant,” they typically “pass within 1 to 2 days.”
While the cause remains unknown in this case, Dr. Wen reiterated that precautions such as thorough hand washing are critical. She also noted that norovirus is not killed by alcohol-based hand sanitizers that are commonly used.
