Cruise Ship Travel
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.
Cruise Ship Medical Capabilities
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:
- Provide emergency medical care for passengers and crew
- Stabilize patients and initiate reasonable diagnostic and therapeutic interventions
- Facilitate the evacuation of seriously ill or injured patients
Illnesses and Injury Aboard Cruise Ships
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:
- Passengers and their clinicians should consult CDC’s Travelers’ Health website (www.cdc.gov/travel) before travel for updates on outbreaks and travel health notices.
- Passengers ill with communicable diseases before a voyage should delay travel until they are no longer contagious. When booking a cruise, travelers should check to see what the trip cancellation policies are, as well as consider purchasing trip cancellation insurance.
- Passengers who become ill during the voyage should seek care in the ship’s medical center to receive clinical management, facilitate infection-control measures, and maximize reporting of potential public health events.
Specific Health Risks
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:
- Washing hands with soap and water often, especially before eating and after using the restroom.
- Promptly calling the ship’s medical center and follow cruise ship guidance regarding isolation and other infection-control measures, even for mild symptoms of a GI illness (see Chapter 4, Norovirus).
- Additional information on cruise ship GI illnesses is available at www.cdc.gov/nceh/vsp/.
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:
- All travelers planning a cruise should have the current seasonal influenza vaccine (as long as there is no contraindication and if available) at least 2 weeks before travel.
- Passengers at high risk for influenza complications should discuss antiviral treatment and chemoprophylaxis with their health care provider before travel.
- Passengers should practice good respiratory hygiene and cough etiquette.
- Passengers should report their respiratory illness to the medical center promptly and follow isolation recommendations, if indicated.
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:
- Obtain a thorough travel history of all destinations during the 10 days before symptom onset (to assist in the identification of potential sources of exposure).
- Collect urine for antigen testing, which detects L. pneumophila serogroup 1 (the most common serogroup).
- Culture lower respiratory secretions on selective media, which is important for detection of non–L. pneumophila serogroup 1 species and serogroups and is useful for comparing clinical isolates to environmental isolates during an outbreak investigation.
- Inform CDC of any travel-associated Legionnaires’ disease cases by sending an email to email@example.com. Cases of Legionnaires’ disease should be quickly reported to public health officials in order to determine if there are links to previously reported cases and to stop potential clusters and new outbreaks.
Vaccine-Preventable Diseases (VPDs)
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:
- All passengers should be up-to-date with routine vaccinations before travel, as well as any required or recommended vaccinations specific for their destinations.
- Women of childbearing age should be immune to measles, varicella and rubella before cruise ship travel.
- Crew members should have documented proof of immunity to VPDs (see Chapter 2, Vaccination & Immunoprophylaxis: General Recommendations).
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:
- Use an Environmental Protection Agency (EPA)-registered insect repellent (see Chapter 3, Mosquitoes, Ticks & Other Arthropods).
- Treat clothing and gear with permethrin or purchase permethrin-treated items.
- While indoors, remain in well-screened or air-conditioned areas.
- When outdoors, wear long-sleeved shirts, long pants, boots, and hats.
- Obtain yellow fever vaccination if recommended or required.
- Take antimalarial chemoprophylaxis if needed (see Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country).
Other Health Concerns
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.
Preventive Measures for Cruise Ship Travelers
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).
Box 8-2. Cruise travel health precautions
Advice for Clinicians Giving Pretravel Cruise Consultations
Risk Assessment and Risk Communication
- Discuss itinerary, including season, duration of travel, and activities at port stops.
- Review the traveler’s medical and immunization history, allergies, and special health needs.
- Discuss relevant travel-specific health hazards and risk reduction.
- Provide the traveler with documentation of his or her medical history, immunizations, and medications.
Immunization and Risk Management
- Provide immunizations that are routinely recommended (age-specific), required (yellow fever), and recommended based on risk.
- Discuss food and water precautions and insect-bite prevention.
- Older travelers, especially those with a history of heart disease, should carry a baseline electrocardiogram to facilitate onboard or overseas medical care.
Medications Based on Risk and Need
- Consider malaria chemoprophylaxis if itinerary includes port stops in malaria-endemic areas.
- Consider motion sickness medications for self-treatment (see Motion Sickness in this chapter).
Precautions for Cruise Ship Travelers
- Evaluate the type and length of the planned cruise in the context of personal health requirements.
- Consult medical and dental providers before cruise travel.
- Notify cruise line of special needs (such as wheelchair access, dialysis, oxygen tank).
- Consider additional insurance for overseas health care and medical evacuation.
- Carry prescription medications in original containers, with a copy of the prescription and accompanying physician’s letter.
- Bring EPA-registered insect repellent and sunscreen, and consider treating clothes and gear with permethrin.
- Defer travel while acutely ill.
- Consult wwwnc.cdc.gov/travel/notices for travel health notices.
- Check www.cdc.gov/nceh/vsp/surv/gilist.htm for gastrointestinal outbreaks.
- Wash hands frequently with soap and water. If soap and water are not available, use an alcohol-based sanitizer that contains ≥60% alcohol.
- Follow safe food and water precautions when eating off the ship at ports of call.
- Use measures to prevent insect bites during port visits, especially in malaria- or dengue-endemic areas or areas where outbreaks of vectorborne diseases, such as chikungunya and Zika, are occurring.
- Use sun protection.
- Maintain good fluid intake, and avoid excessive alcohol consumption.
- Avoid contact with ill people.
- If sexually active, practice safe sex.
- Report illness to ship’s medical center and follow medical recommendations.
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Kara Tardivel, Stefanie B. White, Krista Kornylo Duong