A CDC investigation into the cause of a gastrointestinal illness that infected 284 passengers and 34 crew members on a Princess Cruise line was inconclusive.
Epidemiologists from the CDC's Vessel Sanitation Program led a field response effort March 5 while the ship was docked in Galveston, Texas, according to an update posted on the agency's website. Passengers and crew had been on the voyage since Feb. 26. Those who became ill reported symptoms of vomiting and diarrhea.
A spokesperson for Princess Cruises told CBS they suspect it was norovirus.
"The gastrointestinal illness cases reported are totals for the entire voyage and do not represent the number of active (symptomatic) gastrointestinal cases at any given port of call or at disembarkation," the CDC noted.
To prevent further spread of the illness with an unknown cause, crew members increased sanitation efforts on the vessel and collected samples from infected passengers to aid the CDC's investigation.
Gastrointestinal illness outbreaks are frequently associated with cruise ships, but "Health officials track illness on cruise ships. So outbreaks are found and reported more quickly on a cruise ship than on land," according to the CDC. Living in close quarters also contributes to the quick spread of infections, the agency said.