July 8, 2025, 12:03 pm | Read time: 5 minutes
In recent months, several cruise ships have experienced significant outbreaks of the norovirus. This highly infectious and resilient pathogen causes severe gastrointestinal illnesses in humans. According to the U.S. Centers for Disease Control and Prevention, there were nearly as many outbreaks by mid-2025 as there were in the entire previous year. TRAVELBOOK discussed this with an expert.
If you’re planning a cruise, be aware: If a virus outbreak occurs on board, the risk of infection is significantly increased. This was also the reason why the German Foreign Office advised against this type of vacation during the coronavirus pandemic. Cruise ships, like communal facilities, are places where viral pathogens can spread particularly quickly. This is especially true for the highly contagious norovirus.
Overview
Increase in Norovirus Outbreaks on Cruise Ships
The U.S. Centers for Disease Control and Prevention (CDC) considers a norovirus outbreak on a cruise ship official when at least three percent of passengers or crew members show symptoms of infection. These include diarrhea, nausea, and vomiting. By mid-May 2025, the CDC’s Vessel Sanitation Program (VSP) – responsible for the health of ship travelers – had already recorded 12 confirmed norovirus outbreaks on cruise ships. For comparison: There were 15 in all of 2024; the numbers have been rising since 2023.
Among the recently particularly affected cruise ships is Royal Caribbean’s “Radiance of the Seas.” During a Caribbean cruise in early February, more than 160 passengers and crew members contracted the virus. According to CDC data, there were also 266 cases on the “Queen Mary 2” in March of this year. Holland America Line’s “Eurodam” also reported a noticeable increase in April and May. There is talk of a new variant and a lack of basic immunity in the population. TRAVELBOOK will speak with an expert on this matter below.
How Norovirus Infection Occurs
Norovirus is the most common cause of what is colloquially known as stomach flu, as explained in more detail by the colleagues at FITBOOK. It spreads particularly quickly when people are in close quarters. This is the case in training or care facilities, and also on cruise ships. Droplet infections are also possible, but noroviruses are mostly transmitted through contact infections, such as direct skin contact or touching contaminated objects like door handles, flush buttons, or tabletops. The sudden symptoms of a norovirus infection include gastrointestinal issues like diarrhea and vomiting, and sometimes fever. If those affected do not wash their hands thoroughly after using the restroom, they can spread the virus on various surfaces they come into contact with. The viruses are very resilient and can remain infectious on surfaces for days.
The acute symptoms of a norovirus infection usually subside after three days at the latest. However, those affected can still be contagious, as the viruses are excreted in the stool for some time. Even after recovery, it is important to maintain hygiene and ideally use a separate toilet or thoroughly disinfect sanitary facilities after each use. Indeed, isolating patients on a cruise is challenging.
Expert Explains the Current Increased Transmissibility
TRAVELBOOK spoke with ship doctor and author Dr. Reinhard Friedl (his book “A Doctor for Every Wave” will be available from July 23 at Goldmann Verlag). He knows from experience that norovirus is a common cause of gastrointestinal infections on cruise ships. In the “Mein Schiff” fleet, he has not yet experienced severe outbreaks that led to the shutdown of ships. “That’s due to our strict hygiene measures,” says the doctor.
Currently, a specific variant is circulating, reports the expert. “The genotype GII.17 is partly responsible for the increase in cases at sea and on land. Through mutations, it can change its binding properties and antigen characteristics, making it less recognizable by our immune system.” To explain: Noroviruses are highly adaptable. They can change through small alterations in their genetic material, known as mutations. Binding properties refer to the ability of noroviruses to attach to specific receptors on the cells of our intestinal lining to trigger an infection. The prevailing variant can also alter its surface structure (antigens). This means the immune system no longer reliably recognizes the pathogen. “This facilitates increased transmissibility and rapid spread,” says Dr. Friedl.
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Tips for Protecting Against Norovirus on Cruise Ships
A past viral infection means that those who recover are immune to the corresponding pathogen – at least for a certain period. Norovirus is one of the particularly variable pathogens. An infection therefore only offers temporary protection. “You can get reinfected repeatedly. That’s why it’s so difficult to develop an effective vaccine,” reports Dr. Friedl. It is therefore always of utmost importance to be cautious to best protect against norovirus infection on cruise ships. The expert offers the following behavioral recommendations:
1. Regular Handwashing
The most important protection is regular and thorough handwashing with soap. Also, avoid touching your face with your hands, as viruses can easily enter the body through the mouth, nose, and eyes.
2. Use Disinfectants
Disinfectant dispensers are usually available on board cruise ships – use them consistently in the event of a virus outbreak. If in doubt, it is also advisable to carry your own hand sanitizer.
3. Follow Cough and Sneeze Etiquette
Cough or sneeze into your elbow to prevent the spread of germs. This is especially important in confined areas like restaurants, elevators, or showrooms.
4. Be Cautious on Shore Excursions
In some ports of call, hygiene standards do not meet European standards. Eat only thoroughly cooked food and drink only from originally sealed bottles.
5. Seek Medical Advice Immediately if Symptoms Occur
If you feel unwell, contact the onboard clinic immediately. Modern PCR tests can help quickly determine the cause.