GENEVA, May 18 (Xinhua) -- Recent outbreaks aboard several cruise ships have raised renewed concerns about infectious disease risks in the global cruise industry. In response, World Health Organization (WHO) experts recently explained to Xinhua why infectious illnesses can spread onboard, how frequently such outbreaks occur, and what measures are used to contain them.
Why are cruise ships vulnerable to infectious disease outbreaks?
WHO spokesperson Christian Lindmeier said ships are considered high-risk settings because passengers and crew live, dine and participate in activities in close proximity while sharing food sources, ventilation systems, water facilities and recreational spaces.
However, Lindmeier stressed that infectious disease outbreaks on cruise ships remain relatively uncommon compared with the millions of passengers who travel by sea annually.
He said gastrointestinal illnesses, primarily caused by norovirus, account for the majority of reported diarrhoeal events on cruise ships, and are usually brought under control quickly through established hygiene and public health measures.
What happened in the recent cruise ship outbreaks?
Earlier this month, Dutch-flagged expedition cruise ship MV Hondius, operated by Oceanwide Expeditions, reported multiple cases of hantavirus during a voyage off West Africa, prompting medical evacuations and quarantine measures.
The outbreak has resulted in three confirmed deaths and at least 11 reported cases linked to the Andes strain of hantavirus. Around two dozen crew members and medical staff entered precautionary quarantine in the Netherlands on Monday, while former passengers are being monitored across multiple countries, including Canada, France, Spain and the United States.
In April, the Caribbean Princess, operated by Princess Cruises, experienced a norovirus outbreak that sickened dozens of passengers and crew during a Caribbean voyage. Last week, the British cruise ship Ambition, carrying more than 1500 passengers, was also hit by a norovirus outbreak. Despite 49 confirmed infections, French authorities allowed the vessel to depart Bordeaux after enhanced sanitation and isolation measures were implemented onboard.
Lindmeier said there is no single global surveillance system covering all infectious disease events on cruise ships worldwide. Information instead comes from scientific literature, national surveillance systems, and port health notifications.
Available surveillance programmes, such as the U.S. CDC Vessel Sanitation Program, suggest that norovirus remains the predominant cause of gastrointestinal outbreaks on cruise ships, he said.
How are cruise ship outbreaks regulated and controlled?
Under the International Health Regulations (IHR), ships are required to report any potential public health risk to the next port of call as soon as it is identified, including suspected infectious diseases or unusual health events. Ships are also inspected under the IHR framework to issue Ship Sanitation Certificates, according to WHO rules.
In addition, specialized programmes such as the European Joint Action on Ship Sanitation (SHIPSAN) and the U.S. Vessel Sanitation Program (VSP) set specific standards. Cruise lines should have detailed outbreak management protocols, including isolation, enhanced cleaning, contact tracing, medical monitoring, environmental measures, and coordination with port and public health authorities.
SHIPSAN, supported by the European Commission and coordinated by public health authorities in several EU member states, promotes standardized inspection procedures, hygiene guidelines and disease-control measures across European ports. Its guidelines cover food safety, water quality, waste management, ventilation systems, pest control and the prevention of communicable diseases.
What can be done to reduce outbreak risks onboard?
To reduce outbreak risks, WHO recommends that ships implement strict public health measures, including regular cleaning and disinfection, water and food safety plans, ventilation monitoring, environmental health inspections and onboard disease surveillance systems.
WHO experts added that different types of cruises may present different risks. For example, expedition cruises involving closer contact with wildlife or remote environments may require additional preventive measures. Passengers and crew are also encouraged to follow onboard health protocols, including early reporting of symptoms, isolation when required, hand hygiene, and other infection prevention practices.
Lindmeier stressed that existing surveillance and response frameworks are designed to ensure rapid detection and control once cases emerge. ■
