Cruise ships, often marketed as relaxing, all-inclusive holidays at sea, continue to face a heightened risk of disease outbreaks due to their unique environment, public health experts say.
Vikram Niranjan, an assistant professor at the University of Limerick, has cautioned that these “floating cities” create ideal conditions for infections to spread rapidly and are difficult to control once outbreaks begin.
The warning follows a recent incident aboard the MV Hondius, where three passengers died after contracting a rare strain of hantavirus. The vessel had departed from Argentina about a month earlier. According to the World Health Organization, three additional symptomatic passengers were evacuated to the Netherlands for treatment, while around 150 people remain confined to their cabins as the ship stays anchored off Cape Verde during disinfection efforts.
Experts say the structure and daily routines aboard cruise ships contribute significantly to the spread of infectious diseases. Shared dining spaces, particularly buffet-style services, increase the risk of contamination, while close contact in common areas such as restaurants, theatres, lifts and spas facilitates person-to-person transmission.
Dr Niranjan noted that illnesses such as COVID-19, norovirus, and Legionnaires' disease have all been linked to cruise environments. He cited the Diamond Princess COVID-19 outbreak as a prominent example, where more than 600 passengers and crew tested positive.
Studies have shown that norovirus, often referred to as the “vomiting bug,” is particularly common on cruise ships, with outbreaks frequently tied to contaminated food, shared utensils and high-contact surfaces. Experts warn that individuals who are infected but not yet showing symptoms can unknowingly spread the virus.
The design of cruise ships also plays a role. Passengers and crew spend extended periods in enclosed or semi-enclosed spaces, and ventilation systems may not always effectively limit airborne transmission in crowded settings.
Demographics further increase risks, as cruise travel is especially popular among older adults, many of whom may have underlying health conditions that make infections more severe. While ships are equipped with medical facilities, these are generally limited and not designed to manage large-scale outbreaks.
Although rare, diseases such as hantavirus can also emerge in such environments, typically linked to rodent exposure. Experts say the recent incident underscores how quickly infections can spread in confined settings.
To reduce risks, health specialists recommend that passengers ensure vaccinations are up to date before the voyage and obtain travel insurance covering medical emergencies. Onboard, regular handwashing with soap and water remains the most effective defense against infections like norovirus, while avoiding crowded areas and reporting symptoms early can help limit transmission.