Cruise ships, often marketed as stress-free, all-inclusive holidays at sea, are particularly vulnerable to disease outbreaks, according to an expert. Vikram Niranjan, an assistant professor in public health at the University of Limerick, has warned that these 'floating cities' facilitate the spread of infections in ways that are 'hard to stop'.
His comments come after three passengers on the Dutch cruise ship MV Hondius died from a rare strain of hantavirus, following its departure from Argentina roughly a month ago. The World Health Organisation confirmed that three additional individuals exhibiting symptoms have been evacuated from the vessel to receive medical care in the Netherlands. Approximately 150 people remain onboard, confined to their cabins while disinfection and other public health measures are carried out, as the ship remains anchored off Cape Verde.
Why Cruise Ships Are Hotbeds for Disease
Dr Niranjan explained that buffet-style dining, ship design, and ventilation systems all contribute to the rapid transmission of diseases such as Covid-19, norovirus, and legionnaires' disease. 'The basic structure of cruise travel still creates the same challenge: many people sharing the same meals, the same air, the same water systems and the same common spaces,' he wrote in The Conversation. 'That is why outbreaks keep returning, and why cruise ships remain a useful reminder that public health is shaped as much by design as by germs.'
The outbreak of the rare, rat-borne illness, which carries a 40 per cent mortality rate, has resulted in three deaths and several serious illnesses. Dr Niranjan referenced the 2020 Diamond Princess outbreak, where 619 passengers and crew tested positive for Covid-19, as a well-known example. Researchers found that conditions on the ship facilitated the spread of the coronavirus.
Norovirus: The Cruise Ship Staple
Norovirus, commonly known as the vomiting bug, is the infection most closely linked to cruise ships. A review of previously published studies identified 127 reports of norovirus outbreaks on cruise ships, many linked to contaminated food, surfaces, and person-to-person spread. 'Food service plays a big part in this risk,' Dr Niranjan said. 'Buffet-style dining, shared utensils and many people touching the same surfaces can make it easier for stomach bugs to spread. If someone is infected but does not yet feel sick, they may still contaminate food or surfaces before they realise they are unwell.'
The design of these ships exacerbates the issue, as passengers spend considerable time together in dining areas, bars, lifts, corridors, theatres, and spas. Crew members also live and work in the same environment, often in shared accommodation.
Ventilation and Age Factors
'Ventilation also plays a crucial role,' Dr Niranjan added. 'Cruise ships are not closed boxes, but they do rely heavily on indoor spaces where people spend long periods together. Studies into cruise ship air quality have shown that illness can spread more easily in crowded, enclosed spaces, like cabins, restaurants and entertainment venues, if the ventilation system is not up to scratch.'
Age is another factor, as cruise holidays are particularly popular among older adults, many of whom have long-term health conditions that make infections more serious. While cruise ships have medical facilities, these are limited compared to land-based hospitals and are not designed to handle fast-moving outbreaks.
Legionnaires' Disease and Hantavirus
Dr Niranjan noted that legionnaires' disease, a serious lung infection caused by bacteria, can spread easily through contaminated water systems, with a well-known outbreak linked to a whirlpool spa. Hantavirus, a severe respiratory illness spread by rodents, is rare on ships, but as the recent deaths on the MV Hondius demonstrate, germs in close quarters find it much easier to spread.
How to Protect Yourself
To limit risk, the best protection starts before boarding, Dr Niranjan advised. This includes ensuring routine vaccines are up to date and that travel insurance covers illness-related disruptions. 'Once on board, washing your hands with soap and water is the most useful step for preventing stomach bugs like norovirus,' he said. 'Hand sanitiser can help, but it does not replace soap and water. If you start to feel unwell, the safest move is to avoid buffets and crowded shared spaces and report symptoms early rather than trying to carry on as normal.'
Hantavirus Symptoms
Early symptoms include fever, fatigue, muscle aches, headaches, chills, dizziness, nausea, vomiting, and diarrhoea. Late symptoms, appearing four to 10 days after the initial phase, include coughing, shortness of breath, and potential tightness in the chest as the lungs fill with fluid. Potential complications include haemorrhagic fever with renal syndrome (HFRS), which can cause intense headaches, back and abdominal pain, fever, chills, nausea, blurred vision, and flushing of the face, inflammation of the eyes, or a rash. Later symptoms can include low blood pressure, lack of blood flow, internal bleeding, and acute kidney failure. Hantavirus pulmonary syndrome (HPS) can cause significant shortness of breath, coughing, and low blood pressure due to fluid filling the lungs, and is often fatal.
