More than 140 people on board two cruise ships were sickened in two gastrointestinal illness outbreaks, according to U.S. Centers for Disease Control and Prevention updates issued this week.

The agency said on Wednesday that a norovirus outbreak occurred on Holland America’s Eurodam, with 109 passengers and 13 crew members reporting illnesses. Their primary symptoms were diarrhea and vomiting due to the virus.

An outbreak of illnesses was also reported on the Oceania Cruises’ Oceania Nautica, with 18 passengers and 20 crew reporting symptoms, the CDC said. The cause was currently listed by the CDC as “unknown.”

A total of 2,139 passengers and 832 crew workers are on board the Eurodam cruise, while 639 passengers and 398 crew are on board the Oceania Nautica, the CDC said.

Both ships’ cruise trips are scheduled to end on Wednesday, according to the CDC.

The CDC said that each ship operator has taken steps to mitigate the spread of the outbreak, including more cleaning and disinfection procedures, isolating sick passengers and crew, and collecting samples to submit to the agency.

The announcement follows a series of other norovirus outbreaks on cruises in recent weeks impacting lines operated by Princess Cruises, Cunard Line, and Holland America.

Five outbreaks involved Cunard Line’s Queen Mary 2 in two separate incidents, Holland America Line’s Rotterdam, Princess Cruises’ Ruby Princess, and Holland America Line’s Zuiderdam, the CDC said on Dec. 31, 2024.

The primary symptoms in all five outbreaks included diarrhea and vomiting, according to the CDC. Abdominal cramps were also reported in the two separate Queen Mary 2 outbreaks.

More than 18 outbreaks of gastrointestinal illness were reported on cruise ships throughout 2024, the CDC said. Norovirus was the causative agent for 14 of them.

In 2023, the CDC reported 14 outbreaks on cruise ships, with all but one being caused by norovirus. One outbreak was caused by salmonella.

“Norovirus is often a cause of [gastrointestinal] outbreaks on cruise ships, but we don’t always know the cause of the outbreak when we begin an investigation,” the agency has said. “Finding the agent that caused an outbreak (causative agent) can take time.”

Health officials say that symptoms of norovirus include vomiting, diarrhea, and nausea. The virus also spreads easily through contaminated food or surfaces or through close contact.

Symptoms of the virus generally start 12 to 48 hours after exposure, the Mayo Clinic says.

Symptoms such as vomiting and diarrhea tend to last for one to three days. While most people recover without treatment, some people—such as older adults or young children—have to seek medical attention due to dehydration caused by vomiting and diarrhea, it says.

Norovirus causes an average of 900 deaths and 109,000 hospitalizations annually in the United States, mostly among adults aged 65 and older, officials say. It also leads to 465,000 emergency department visits, mostly involving young children.

Overall U.S. cases of norovirus have increased in recent days, federal officials say. The most recent data published by the CDC show that there were 91 outbreaks of the virus for the week ending Dec. 5, 2024, the most recent update on the virus that is available.

The Associated Press contributed to this report.