At a glance
Learn about the gastrointestinal illness outbreak on Viking Ocean Cruises II Ltd. ship Viking Mars, including outbreak details and actions taken in response.
Outbreak details
Cruise line: Viking Ocean Cruises II Ltd.
Cruise ship: Viking Mars
Voyage dates: January 10, 2025–January 24, 2025
Voyage number: 10005431
Date outbreak reported to VSP: January 19, 2025
Final case counts:
- Number of passengers who reported being ill during the voyage out of total number of passengers onboard: 62 of 887 (6.99%)
- Number of crew who reported being ill during the voyage out of total number of crew onboard: 9 of 465 (1.94%)
Predominant symptoms: diarrhea, vomiting
Causative agent: unknown
Actions in response to the outbreak
In response to the outbreak, Viking Ocean Cruises II Ltd. and the crew aboard the ship reported the following actions:
- Increased cleaning and disinfection procedures according to their outbreak prevention and response plan
- Collected stool specimens from gastrointestinal illness cases for testing
- Isolated ill passengers and crew
VSP remotely monitored the situation, including review of the ship's outbreak response and sanitation procedures.
More information
Tracking GI illnesses
Gastrointestinal illness is a commonly used term for acute gastroenteritis (AGE). Reporting gastrointestinal illness is important. When passengers and crew tell the medical center onboard about their symptoms, it helps GI outbreaks get detected quickly. This allows steps to be taken to limit the spread of illness. Medical staff evaluate symptoms to see if they meet our case definition for AGE:
- Three or more loose stools within a 24-hour period or what is more than normal for that person OR
- Vomiting along with one of the following symptoms: diarrhea, muscle ache, headache, abdominal cramp, or fever
Cruise ships are required to report these cases to us.
Note: Cases reported are totals for the entire voyage. It does not mean all people are sick at the same time, such as when they arrive or leave a port or ship.
Finding causative agents
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. Finding the agent that caused an outbreak (causative agent) can take time. When an outbreak occurs, people whose symptoms met the case definition are asked to provide stool or vomitus samples. These samples are tested to determine the causative agent.
In this outbreak, samples are pending confirmatory testing.
Learn more about AGE monitoring and how VSP responds to AGE outbreaks.