At a glance
Learn about the gastrointestinal illness outbreak on the Lindblad Expeditions ship National Geographic Sea Lion, including outbreak details and actions taken in response.
Outbreak details
Cruise line: Lindblad Expeditions
Cruise ship: National Geographic Sea Lion
Voyage dates: April 15, 2025–April 29, 2025
Voyage number: SL 22512
Outbreak reported to VSP: April 21, 2025
Final case counts:
- Number of passengers who reported being ill during the voyage out of total number of passengers onboard: 5 of 43 (11.6%)
- Number of crew who reported being ill during the voyage out of the total number of crew onboard: 2 of 37 (5.4%)
Predominant symptoms: vomiting, fever, diarrhea
Causative agent: unknown
Actions in response to the outbreak
In response to the outbreak, Lindblad Expeditions and the crew aboard the ship reported the following actions:
- Increased cleaning and disinfection procedures according to their outbreak prevention and response plan
- Isolated ill passengers and crew
- Consulted with VSP about sanitation cleaning procedures and reporting ill cases
VSP remotely monitored the situation, including review of the ship’s outbreak response and sanitation procedures.
More information
Tracking gastrointestinal illnesses
Gastrointestinal (GI) 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 illness 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 illness 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, people whose symptoms met the case definition did not provide samples.