Cruise ships susceptible to rapid spread of infectious disease

Large numbers & close quarters allow viruses to travel quickly

Submitted by Parkview Health

Vacationers hitting the seas on cruise ships set sail for fun and sun, but travelers should also be aware of the unique risks they can face from infectious diseases.

After a recent, deadly outbreak of hantavirus identified on board a Dutch-flagged cruise ship traveling from Argentina to Europe, Dr. Michael Davis, Parkview Physicians Group – Infectious Disease, reminds that viruses can chain quickly in confined spaces and spread far and wide when they infect travelers.

Davis

“As we continue to live in a globalized world with increased human-to-human contact, climate change and evolving microbes, we will continue to see the occasional outbreak of uniquely adapted microbes,” Davis said. “Cruise ships simply offer one of the best breeding grounds for the spread of microbes that, otherwise, don’t typically spread from human to human.”

The recent hantavirus outbreak on board a cruise ship that left Argentina on April 1 raised concerns, as that virus, which is common in rodents and other animals, is not usually contagious between humans. But passengers aboard the ship became ill with symptoms of a rare Andes strain that then spread among others aboard the ship, transiting back to Europe.

Cruises are safe, but disease outbreaks are not uncommon, with about a dozen reported per year on average, according to data recorded by the Centers for Disease Control and Prevention. In 2025, the CDC recorded 23 cruise ship outbreaks, defined as 3 percent or more of the total ship population experiencing symptoms of an illness.

Cruise ships have several features that make it easy for disease to spread, Davis said. Cruises bring together a large number of people in a confined space, with lots of overlapping interactions in dining halls and recreational spaces where people can easily pass viruses among each other.

“Most often, we see the spread of respiratory viruses and gastrointestinal viruses between passengers,” Davis said. “Cruise ships carry a few thousand passengers who are in close contact with each other, sharing common spaces for a week, touching contaminated surfaces, and breathing shared air. Crowded and contained areas with large volumes of people offer an ideal situation for transmission.”

Norovirus, which can cause sudden onset of nausea, abdominal cramping, and diarrhea, is the most notorious virus that impacts cruise ships. Of the 23 outbreaks catalogued by the CDC in 2025, norovirus was identified as the responsible pathogen in 18 of those cases.

Respiratory viruses encountered on cruise ships generally result in common flu-like illnesses with cough, nasal congestion, headache, and body aches, Davis said. In the early days of the COVID-19 pandemic, ship-based outbreaks were one of the first large instances of rapid transmission of that virus.

Most who encounter these communicable infections will recover after several days, Davis said. However, those travelers with weakened immune systems are at risk for more severe disease. Although large cruise ships offer medical facilities for travelers in need, they don’t have the treatment capabilities of a traditional hospital.

Davis said the recent hantavirus outbreak is a concerning albeit unusual case, since human-to-human transmission is limited to one rare strain. Future outbreaks are unlikely, Davis explained, so hantavirus is probably not a reason for anyone to cancel upcoming trips.

That said, anyone planning to take a cruise should be aware of the risks of exposure to other ship-based illnesses.

“At the moment, I wouldn’t expect the current hantavirus outbreak to cause differing safety concerns for future cruises,” Davis said. “But when embarking on cruise travel, it’s important to keep in mind the risks of acquiring a communicable infection and take necessary risk reduction measures to decrease the chances of picking up one of these viruses.”