Author(s): Kara Tardivel, Stefanie White, Aimee Treffiletti, Amy Freeland

Cruise ship travel presents a unique combination of health concerns. Travelers from diverse regions brought together in the often crowded, semi-enclosed shipboard environment can facilitate the spread of person-to-person, foodborne, and waterborne diseases. Outbreaks on ships can be sustained over multiple voyages by crewmembers who remain onboard, or by persistent environmental contamination. Port visits can expose travelers to local diseases and, conversely, be a conduit for disease introduction into shoreside communities.

Some people (e.g., those with chronic health conditions or who are immunocompromised, older people, pregnant people) merit additional considerations when preparing for a cruise. Because travelers at sea might need to rely on a ship’s medical capabilities for an extended period, potential cruise passengers with preexisting medical needs should prepare accordingly by calling the cruise line’s customer service center to learn what type and level of health care services are (and are not) available on specific ships.

Cruise Ship Medical Capabilities

Medical facilities on cruise ships can vary widely depending on ship size, itinerary, cruise duration, and passenger demographics. Generally, shipboard medical centers can provide medical care comparable to that of ambulatory care centers; some are capable of providing hospitalization services or renal dialysis. Although no agency officially regulates medical practice aboard cruise ships, the American College of Emergency Physicians (ACEP) published consensus-based guidelines for cruise ship medical facilities in 1995, and updated the guidelines in 2013. ACEP guidelines, which most major cruise lines follow, state that cruise ship medical facilities should be able to provide quality medical care for passengers and crew; initiate appropriate stabilization, diagnostic, and therapeutic maneuvers for critically ill or medically unstable patients; and assist in the medical evacuation of patients in a timely fashion, when appropriate.

Illness & Injury

Cruise ship medical centers deal with a wide variety of illnesses and injuries; ≈10% of conditions reported to cruise ship medical centers are an emergency or require urgent care. Approximately 95% of illnesses are treated or managed onboard, with the remainder requiring evacuation and shoreside consultation for dental, medical, or surgical issues. Roughly half of all passengers seeking medical care are >65 years old.

Medical center visits are primarily the result of acute illness or injury. The most frequently reported diagnoses include respiratory illnesses (30%–40%); injuries from slips, trips, or falls (12%–18%); seasickness (10%); and gastrointestinal (GI) illness (10%); 80% of onboard deaths are due to cardiovascular events.

Infectious Disease Outbreaks

The most frequently reported cruise ship outbreaks involve GI infections (e.g., norovirus), respiratory infections (e.g., coronavirus disease 2019 [COVID-19], influenza), and other vaccine-preventable diseases (VPDs), such as varicella. Although cruise ships do not have public health authority, to reduce the risk of introducing communicable diseases, some ships conduct medical screening during embarkation to identify ill passengers, prevent them from boarding, or require isolation if permission to board is given.

Before travel, to help limit the introduction and spread of communicable diseases on cruise ships, prospective cruise ship travelers and their clinicians should consult the Centers for Disease Control and Prevention (CDC) Travelers’ Health website for updates on outbreaks and destination-specific travel health notices. People who become ill with a communicable disease before a voyage should consult their health care provider and delay their travel until they are no longer contagious. When booking a cruise, travelers should check the trip cancellation policies and consider purchasing trip cancellation insurance (see Sec. 6, Ch. 1, Travel Insurance, Travel Health Insurance & Medical Evacuation Insurance).

Travelers who become ill during a voyage should seek care in the ship’s medical center; the onboard staff will provide clinical management, facilitate infection-control measures, and take responsibility for reporting potential public health events. For information on how to report travelers who become ill with suspected communicable diseases after they return home from a cruise, see Sec. 8, Ch. 8, Airplanes & Cruise Ships: Illness & Death Reporting & Public Health Interventions.

Infectious Disease Health Risks

Gastrointestinal Illnesses

During 2006–2019, rates of GI illness among passengers on voyages lasting 3–21 days fell from 32.5 to 16.9 cases per 100,000 travel days. Despite the decrease, outbreaks continue to occur. CDC assists the cruise ship industry to prevent and control the introduction, transmission, and spread of GI illnesses on cruise ships. See information on cruise ship GI illnesses and updates on GI illness outbreaks involving ships with US ports of call, specifically.

Norovirus

On cruise ships, >90% of GI illness outbreaks with a confirmed cause are due to norovirus. Characteristics of norovirus that facilitate outbreaks include a low infective dose, easy person-to-person transmissibility, prolonged viral shedding, absence of long-term immunity, and the ability of the virus to survive routine cleaning procedures (see Sec. 5, Part 2, Ch. 16, Norovirus). For international cruise ships porting in the United States during 2006–2019, an average of 12 norovirus outbreaks occurred each year.

Other Sources of Gastrointestinal Illness

GI outbreaks on cruise ships also have been caused by contaminated food or water; most outbreaks were associated with Campylobacter, Clostridium perfringens, or enterotoxigenic Escherichia coli.

Protective Measures

Travelers can reduce the risk of acquiring a GI illness on cruise ships by frequently washing hands with soap and water, especially before eating and after using the restroom. Travelers should call the ship’s medical center promptly, even for mild symptoms of a GI illness, and strictly follow cruise ship guidance regarding isolation and other infection-control measures.

Respiratory Illnesses

Respiratory illnesses are the most common medical complaint on cruise ships. During the pretravel visit, evaluate whether vaccines or boosters (e.g., COVID-19, influenza) are needed and emphasize the importance of practicing good respiratory hygiene and cough etiquette while onboard. As with GI illnesses, cruise ship passengers should report respiratory illness to the medical center promptly and follow isolation recommendations as instructed.

Coronavirus Disease 2019

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, spreads more easily between people in close quarters, and multiple studies have concluded that transmission rates of SARS-CoV-2 among travelers on ships are much greater than in other settings. Cruise ship COVID-19 outbreaks can tax onboard medical and public health resources. Ship-to-shore medical evacuations to facilities capable of providing higher levels of medical care can present logistical challenges and pose additional risks to ill patients.

Cruise passengers and crewmembers who are not up to date with their COVID-19 vaccines are at increased risk for severe illness, hospitalization, medical evacuation, and death. Since cruising will always pose some risk of SARS-CoV-2 transmission, ensure that people planning cruise ship travel are up to date with their vaccinations, and assess their likelihood for developing severe COVID-19. For people at increased risk of severe COVID-19 regardless of their vaccination status (e.g., pregnant people, people who are immunocompromised), discuss the potential health hazards associated with cruise ship travel. CDC has developed recommendations and guidance designed to help cruise ship operators provide a safer and healthier environment for crewmembers, passengers, port personnel, and communities.

Influenza

Historically, influenza has been among the most often reported VPDs occurring on cruise ships. Because passengers and crew originate from all regions of the globe, shipboard outbreaks of influenza A and B can occur year-round, with exposure to strains circulating in different parts of the world (see Sec. 5, Part 2, Ch. 12, Influenza). Thus, anyone planning a cruise should receive the current seasonal influenza vaccine ≥2 weeks before travel if vaccine is available and no contraindications exist. For people at high risk for influenza complications, health care providers should discuss chemoprophylaxis and how and when to initiate antiviral treatment.

See additional guidance on the prevention and control of influenza on cruise ships.

Legionnaires’ Disease

Less common on cruise ships, Legionnaires’ disease is nevertheless a treatable infection that can result in severe pneumonia leading to death (see Sec. 5, Part 1, Ch. 9, Legionnaires’ Disease & Pontiac Fever). Approximately 10%–15% of all Legionnaires’ disease cases reported to CDC occur in people who have traveled during the 10 days before symptom onset. Clusters of Legionnaires’ disease associated with hotel or cruise ship travel can be difficult to detect, because travelers often disperse from the source of infection before symptoms begin. Data reported to CDC during 2014–2015 included 25 confirmed cases of Legionnaires’ disease associated with cruise ship exposures.

In general, Legionnaires’ disease is contracted by inhaling warm, aerosolized water containing the bacteria, Legionella. Transmission also can sometimes occur through aspiration of Legionella-containing water. Typically, people do not spread Legionella to others; a single episode of possible person-to-person transmission of Legionnaires’ disease has been reported. Contaminated hot tubs are commonly implicated as a source of shipboard Legionella outbreaks, although potable water supply systems also have been culpable. Improvements in ship design and standardization of water disinfection have reduced the risk for Legionella growth and colonization.

Diagnosis & Reporting

People with suspected Legionnaires’ disease require prompt antibiotic treatment. When evaluating cruise travelers for Legionnaires’ disease, obtain a thorough travel history of all destinations during the 10 days before symptom onset to assist in identifying potential sources of exposure, and collect urine for Legionella antigen testing. Most cruise ships have the capacity to perform this test, which detects L. pneumophila serogroup 1, the most common serogroup.

Perform culture of lower respiratory secretions on selective media to detect non–L. pneumophila serogroup 1 species and serogroups. Culture also is used for comparing clinical isolates to environmental isolates during an outbreak investigation. Notify CDC of any travel-associated Legionnaires’ disease cases by sending an email to travellegionella@cdc.gov. Quickly report all cases of Legionnaires’ disease to public health officials, who can determine whether a case links to previously reported cases and work to stop potential clusters and new outbreaks.

Other Vaccine-Preventable Diseases

Although most cruise ship passengers come from countries with routine vaccination programs (e.g., Canada, the United States), many of the crew are from low- or middle-income countries where immunization rates can be low. Outbreaks of hepatitis A, measles, meningococcal disease, mumps, pertussis, rubella, and varicella have all been reported on cruise ships. The majority (82%) of these outbreaks occur among crewmembers; prior to the COVID-19 pandemic, varicella was the most frequently reported VPD. Other VPDs (e.g., pertussis) occur more often among passengers.

Each cruise line sets its own policies regarding vaccinations for its crew; some have limited or no requirements. Thus, all passengers should be up to date with routine vaccinations before travel, as well as any required or recommended vaccinations specific for their destinations. People of childbearing age should have documented immunity to measles, rubella, and varicella (either by vaccination or titer) before cruise ship travel.

Vectorborne Diseases

Some cruise ship ports of call include destinations where vectorborne diseases (e.g., dengue, Japanese encephalitis, malaria, yellow fever, Zika) are known to be endemic. In addition, new diseases can surface in unexpected locations; chikungunya was reported for the first time in the Caribbean in late 2013, with subsequent spread throughout the region and numerous other North, Central, and South American countries and territories. Zika was first reported in Brazil in 2015, and subsequently spread across the Caribbean and Latin America, sparking concern because of its association with microcephaly and other congenital abnormalities in the fetus. For disease-specific information, see the relevant chapters of Section 5.

For guidance on how to avoid bites from mosquitoes and other disease-transmitting arthropod vectors, both onboard and while on shore at ports of call, see Sec. 4, Ch. 6, Mosquitoes, Ticks & Other Arthropods. For specific details on yellow fever vaccination and malaria prevention, see Sec. 2, Ch. 5, Yellow Fever Vaccine & Malaria Prevention Information, by Country.

Noninfectious Health Risks

Stresses of cruise ship travel include varying weather and environmental conditions, and unaccustomed changes to diet and levels of physical activity. Despite modern stabilizer systems, seasickness is a common complaint, affecting up to 25% of travelers (see Sec. 8, Ch. 7, Motion Sickness). Note that travel is an independent risk factor for behaviors such as alcohol and illicit drug use and misuse (see Sec. 3, Ch. 5, Substance Use & Substance Use Disorders), and unsafe sex (see Sec. 9, Ch. 12, Sex & Travel).

Travel Preparation

Cruise ship travelers have complex itineraries due to multiple short port visits. Although most port visits do not include overnight stays off ship, some trips offer travelers the opportunity to venture off the ship for ≥1 night. These excursions can complicate decisions about exposures and the need for specific antimicrobial prophylaxis, immunizations, and other prevention measures. Boxes 8-04 and 8-05 summarize recommended cruise travel preparations and healthy behaviors during travel for health care providers and cruise ship travelers.

Travelers with Additional Considerations

Travelers with chronic illnesses and travelers with disabilities who have additional needs (e.g., dialysis, supplemental oxygen, wheelchairs) should inform their cruise line before traveling. Highly allergic travelers and travelers with underlying medical conditions should carry a file that contains essential, pertinent health information (e.g., allergies, blood type, chest radiograph [if abnormal], chronic conditions, electrocardiogram, medication list, primary and/or specialty care provider contact information). Travelers also should bring any medications recommended by their health care provider (e.g., an epinephrine auto-injector) to help facilitate care during a medical emergency. For detailed information on preparing travelers who have additional considerations for international travel, including severe allergies, chronic illness, disabilities, or immune compromise, see Section 3.

Pregnant Travelers

Most cruise lines have policies that do not permit people to board after their 24th week of pregnancy. Contact cruise lines directly for specific guidance before booking. For additional information on preparing pregnant people for international travel, see Sec. 7, Ch. 1, Pregnant Travelers.

Insurance Coverage

All prospective cruise travelers should verify coverage with their health insurance carriers and, if not included, consider purchasing additional insurance to cover medical evacuation and health services received onboard cruise ships and in foreign countries (see Sec. 6, Ch. 1, Travel Insurance, Travel Health Insurance & Medical Evacuation Insurance).