Cruise ship travel presents a unique combination of health concerns. Travelers from diverse regions brought together in the often crowded, semi-enclosed environments onboard ships can facilitate the spread of person-to-person, foodborne, or waterborne diseases. Outbreaks on ships can be sustained for multiple voyages by transmission among crew members who remain onboard or by persistent environmental contamination. Port visits can expose travelers to local vectorborne diseases. The remote location of the travelers at sea means that they may need to rely on the medical capabilities and supplies available onboard the ship for extended periods of time, and cruise travelers and their physicians should be aware of ships’ medical limitations and prepare accordingly. Certain groups, such as pregnant women, the elderly, or those with chronic health conditions or who are immunocompromised, require special consideration when considering cruise travel.
Medical facilities on cruise ships can vary widely depending on ship size, itinerary, length of cruise, and passenger demographics. Generally, shipboard medical centers can provide medical care comparable to that of ambulatory care centers; some can provide hospitalization services. Although no agency officially regulates medical practice aboard cruise ships, consensus-based guidelines for cruise ship medical facilities were published by the American College of Emergency Physicians (ACEP) in 1995 and most recently updated in 2013. ACEP guidelines (www.acep.org/Content.aspx?id=29980), which are followed by most major cruise lines, state that the cruise ship medical facilities should maintain the following minimum capabilities:
Cruise ship medical centers deal with a wide variety of illnesses and injuries. Approximately 3%–11% of conditions reported to cruise ship medical centers are urgent or an emergency. Approximately 95% of illnesses are treated or managed onboard, and 5% require evacuation and shoreside consultation for medical, surgical, or dental problems. Roughly half of passengers who seek medical care are older than 65 years of age. Most medical center visits are due to acute illnesses, of which respiratory illnesses (19%–29%); seasickness (10%–25%); injuries from slips, trips, or falls (12%–18%); and gastrointestinal (GI) illness (9%–10%) are the most frequently reported diagnoses. Death rates for cruise ship passengers, most often from cardiovascular events, range from 0.6 to 9.8 deaths per million passenger-nights.
The most frequently reported cruise ship outbreaks involve respiratory infections, GI infections (such as norovirus), and vaccine-preventable diseases other than influenza, such as varicella (chickenpox). To reduce the risk of onboard introduction of communicable diseases by embarking passengers, ships may conduct medical screening during embarkation to identify ill passengers, preventing them from boarding or requiring isolation if they are allowed to board.
The following measures should be encouraged to limit the introduction and spread of communicable diseases on cruise ships:
From 2008 through 2014, rates of GI illness among passengers on voyages lasting 3–21 days decreased from 27.2 to 22.3 cases per 100,000 travel days. Despite this decrease, GI illness outbreaks continue to occur. Updates on these outbreaks involving ships with US ports of call can be found at www.cdc.gov/nceh/vsp/surv/gilist.htm.
More than 90% of GI outbreaks with a confirmed cause are due to norovirus. Characteristics of norovirus that facilitate outbreaks are a low infective dose, easy person-to-person transmissibility, prolonged viral shedding, no long-term immunity, and the organism’s ability to survive routine cleaning procedures. For international cruise ships porting in the United States from 2010 through 2015, 8–16 outbreaks of norovirus infections occurred each year.
GI outbreaks on cruise ships from food and water sources have also been associated with Salmonella spp., enterotoxigenic Escherichia coli, Shigella spp., Clostridium perfringens , and Cyclospora cayetanensis . To protect themselves from infections and reduce the spread of GI illnesses on cruise ships, passengers should be counseled on the following:
Respiratory illnesses are the most common medical complaint, and influenza is the most commonly reported vaccine-preventable illness on cruise ships. Since passengers and crew originate from all regions of the world, shipboard outbreaks of influenza A and B can occur year-round, and travelers on cruise ships can be exposed to strains circulating in different parts of the world.
Given the cruise ship environment, population, and variable medical capabilities, the following measures are recommended year-round to protect travelers from influenza:
Additional guidance on the prevention and control of influenza on cruise ships is available at www.cdc.gov/quarantine/cruise/management/guidance-cruise-ships-influenza-updated.html. For more information, see Chapter 4, Influenza.
Although it is not a common cause of respiratory illness on cruise ships, Legionnaires’ disease is a treatable infection that can result in severe pneumonia leading to death. 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. From 1977 through 2012, 8 ship-associated outbreaks of Legionnaires’ disease were reported in the literature. These outbreaks included a total of 83 cases, with a median of 4 cases per outbreak (range, 2–50 cases); 6 cases resulted in death.
In general, Legionnaires’ disease is contracted by inhaling warm, aerosolized water containing Legionella . Transmission can also sometimes occur through aspiration of water containing Legionella . A single episode of possible person-to-person transmission of Legionnaires’ disease has been reported. Contaminated hot tubs are a commonly implicated source of shipboard Legionella outbreaks, although potable water supply systems have also been implicated. Improvements in ship design and standardization of water disinfection have reduced the risk of Legionella growth and colonization.
Most cruise ships have health care personnel who can perform Legionella urine antigen testing. People with suspected Legionnaires’ disease require prompt antibiotic treatment. See Chapter 4, Legionellosis (Legionnaires’ Disease & Pontiac Fever) for more information.
In evaluating cruise travelers for Legionnaires’ disease, clinicians should do the following:
Although most cruise ship passengers are from countries with routine vaccination programs (such as the United States and Canada), many crew members originate from developing countries with low immunization rates. Outbreaks of measles, rubella, meningococcal disease and, most commonly, varicella, have been reported on cruise ships. Preventive measures to reduce the spread of VPDs onboard cruise ships should be followed:
Cruise ship port visits may include countries where vectorborne diseases such as malaria, dengue, yellow fever, Japanese encephalitis, and Zika are endemic. New diseases might surface in unexpected locations. For example, chikungunya was reported in late 2013 for the first time in the Caribbean (with subsequent spread throughout the Caribbean and numerous North, Central, and South American countries and territories). Zika virus 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. See Chapter 4 for additional information on specific vectorborne diseases.
Passengers should follow recommendations for avoiding mosquito bites and vectorborne infections:
Stresses of cruise ship travel include varying weather and environmental conditions, as well as unaccustomed changes in diet and physical activity. Foreign travel may increase the likelihood of risk-taking behaviors such as alcohol misuse, drug use, and unsafe sex. In spite of modern stabilizer systems, seasickness is a common complaint, affecting up to one-fourth of travelers (see Motion Sickness later in this chapter).
Because cruise may not allow women to board after the 24th week of pregnancy, pregnant women should contact the cruise line for specific policies recommendations before booking (for additional information, see Chapter 7, Pregnant Travelers).
For reporting travelers that have become ill with a suspect communicable disease after they have returned home from sailing on a cruise ship, please see Appendix D: Airplanes & Cruise Ships: Illness & Death Reporting & Public Health Interventions.
Cruise ship travelers often have complex itineraries due to multiple short port visits. Although most of these port visits do not include overnight stays off the cruise ship, some trips have options for travelers to venture off the ship for ≥1 night. Therefore, cruise ship travelers may be uncertain about potential exposures and which antimicrobial prophylaxis, immunizations, and preventive measures should be considered. Box 8-2 summarizes recommendations for cruise travelers and clinicians advising cruise travelers in pretravel preparation and healthy behaviors during travel.
Travelers with special medical needs, such as wheelchairs, oxygen tanks, or dialysis, should inform their cruise line before traveling. Travelers with health conditions should carry a written summary of essential health information (electrocardiogram; chest radiograph, if abnormal; blood type; chronic conditions; allergies; treating physician contact information; and medication list) that would facilitate their care during a medical emergency.
In addition, 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 in foreign countries (see Chapter 6, Travel Insurance, Travel Health Insurance & Medical Evacuation Insurance).
Risk Assessment and Risk Communication
Immunization and Risk Management
Medications Based on Risk and Need
Kara Tardivel, Stefanie B. White, Krista Kornylo Duong