Cruise Ship Travel
Cruise ships bring together large numbers of people from a variety of communities and backgrounds. Communicable diseases can be introduced onboard by embarking passengers and crew members or acquired during visits to seaports. The crowded, semienclosed environment of the cruise ship can facilitate transmission of infectious diseases from person to person or from contaminated food, water, air, or environmental surfaces. Crew members who remain onboard during successive sailings can sustain transmission of communicable diseases. Certain groups, such as pregnant women, the elderly, and those who are immunocompromised, might be more seriously affected by infectious diseases. In addition, the stress of travel can worsen chronic conditions in any population.
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 clinics can provide medical care comparable to that of ambulatory care centers. Although no official agency 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, most recently updated in 2013. The ACEP guidelines (www.acep.org/content.aspx?id=29500), 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 clinics deal with a wide variety of illnesses and injuries. Approximately 3%–11% of conditions reported to cruise ship infirmaries are urgent or an emergency. Approximately 95% of illnesses are treated or managed onboard, and 5% require evacuation and shoreside consultation for medical, surgical, and dental problems. Approximately half of passengers who seek medical care are older than 65 years. Most (69%–88%) passenger dispensary visits are due to medical conditions, of which respiratory (19%–29%) and gastrointestinal (GI) (9%–10%) illnesses are the most frequently reported diagnoses. Approximately 10%–25% of passengers report seasickness, and injuries (typically from slips, trips, or falls) account for 12%–18% of medical visits. 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 documented cruise ship outbreaks involve respiratory infections (influenza and Legionnaires’ disease), GI infections (norovirus), and vaccine-preventable diseases other than influenza, such as rubella and varicella (chickenpox). To reduce the risk of onboard introduction of communicable diseases by embarking passengers, ships may conduct preembarkation medical screening to identify ill passengers before boarding.
US federal quarantine regulations require ships destined for a US port to immediately report to CDC all shipboard deaths and certain illnesses. CDC guidance for management of common infectious diseases on ships (including varicella, influenzalike illness, and GI illness) and reporting to CDC is available at www.cdc.gov/quarantine/cruise/index.html and www.cdc.gov/nceh/vsp.
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.
- Passengers who become ill during the voyage should seek care in the ship’s infirmary to receive clinical management, facilitate infection control measures, and maximize reporting of potential public health events.
SPECIFIC HEALTH RISKS
CDC’s Vessel Sanitation Program (VSP) conducts twice-yearly, unannounced inspections of ships carrying ≥13 passengers with international itineraries that call on US seaports. In spite of good cruise ship environmental health standards and high VSP inspection scores, outbreaks of gastroenteritis on cruise ships continue to occur. Updates of outbreaks are posted on VSP’s website at www.cdc.gov/nceh/vsp/surv/gilist.htm. More than 90% of GI outbreaks investigated by VSP 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. From 2005 through 2009, approximately 27 outbreaks of norovirus infections occurred on cruise ships each year. To reduce the spread of norovirus on cruise ships, passengers should be counseled on the following:
- Information on cruise ship norovirus outbreaks is available at www.cdc.gov/nceh/vsp.
- Passengers should wash their hands with soap and water often, especially before eating and after using the restroom.
- Passengers who develop a GI illness, even if symptoms are mild, should promptly call the ship’s medical center and follow cruise ship guidance regarding isolation and other infection control measures (see Chapter 3, Norovirus). If no medical center exists, contact the ship’s master to report GI illness.
GI outbreaks on cruise ships from food and water sources have also been associated with Salmonella spp., enterotoxigenic Escherichia coli, Shigella spp., Vibrio spp., Staphylococcus aureus, Clostridium perfringens, Cyclospora cayetanensis, and hepatitis A and E viruses.
Influenza seasons in the Northern and Southern Hemispheres typically occur at opposite times of the year. 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. Using 2008–2011 surveillance data, CDC found a mean rate of influenzalike illness (defined as temperature ≥100°F plus cough or sore throat) of 0.065 cases per 1,000 person-nights, without a detectable seasonal pattern.
During outbreaks, travelers can expect onboard control measures such as isolation of ill people, antiviral treatment of ill people, surveillance for new cases, and prophylaxis of contacts who are at high risk for complications. The following measures are recommended to reduce the spread of influenza aboard cruise ships:
- Clinicians should provide cruise travelers, particularly those at high risk for influenza complications, with the current seasonal influenza vaccine (if available) ≥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 infirmary 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 3, Influenza.Legionnaires’ Disease
Legionnaires’ disease is a severe pneumonia caused by inhalation or possibly aspiration of warm, aerosolized water containing Legionella organisms. The organism is not transmitted from person to person. Contaminated ships’ whirlpool spas and potable water supply systems are the most commonly implicated sources of shipboard Legionella outbreaks. Improvements in ship design and standardization of water disinfection have reduced the risk of Legionella growth and colonization.
Symptom onset is typically 2–10 days after exposure, and older travelers (≥65 years) and those with underlying medical conditions are at increased risk for infection. Most cruise ships can perform Legionella urine antigen testing. People with suspected Legionnaires’ disease require prompt antibiotic treatment. See Chapter 3,Legionellosis (Legionnaires’ Disease & Pontiac Fever) for more information.
More than 20%–25% of all Legionnaires’ disease reported to CDC is travel-associated. Clusters of Legionnaires’ disease associated with hotel or cruise ship travel are difficult to identify, because travelers often disperse from the source of infection before symptoms begin. In evaluating cruise travelers for Legionnaires’ disease, clinicians should do the following:
- Obtain a thorough travel history of all destinations from 10 days before symptom onset (to assist in the identification of potential source of exposure)
- Collect urine for antigen testing
- Collect respiratory secretions for culture, which is essential for identifying the pathogen
- Inform CDC of any travel-associated Legionnaires’ disease cases by sending an email to firstname.lastname@example.org
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, and, most commonly, varicella have been reported on cruise ships. Preventive measures to reduce the spread of VPDs aboard cruise ships should be followed:
- Crew members should have documented proof of immunity to VPDs.
- Passengers, especially older passengers (>65 years) and immunocompromised people, 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 rubella before cruise ship travel.
Cruise ship port visits may include countries where vectorborne diseases, such as malaria, dengue, yellow fever, and Japanese encephalitis 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 in several North, Central, and South American countries), and outbreaks of Zika were reported in the Western Pacific in the first half of 2014. Yellow fever vaccination certificates may be required by some countries for entry.
Passengers should follow recommendations for avoiding mosquito bites and vectorborne infections:
- Use an effective insect repellent (see Chapter 2, Protection against Mosquitoes, Ticks, & Other Arthropods)
- While indoors, remain in well-screened or air-conditioned areas
- When outdoors, wear long-sleeved shirts, long pants, boots, and hats
- Take antimalarial chemoprophylaxis if needed (see Chapter 3, Yellow Fever & Malaria 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 Chapter 2, Motion Sickness).
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, many exotic trips have options for travelers to venture off the ship for ≥1 nights. Therefore, cruise ship travelers may be uncertain about potential exposures and which antimicrobial prophylaxis, immunizations, and preventive measures should be considered. Box 6-1 summarizes recommendations for cruise travelers and clinicians advising cruise travelers in pre-travel 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, 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 consider purchasing additional insurance to cover medical evacuation and health services in foreign countries (see Chapter 2, Travel Insurance, Travel Health Insurance, & Medical Evacuation Insurance).
Box 6-01. Cruise travel health precautions
Advice for Clinicians Giving Pre-Travel Cruise ConsultationsRisk 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.
- 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.
- Consider malaria chemoprophylaxis if itinerary includes port stops in malaria-endemic areas.
- Consider motion sickness medications for self-treatment (see Chapter 2, Motion Sickness).
Precautions for Cruise Ship TravelersPre-Travel
- Evaluate the type and length of the planned cruise in the context of personal health requirements.
- Consult medical and dental care 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 their original containers, with a copy of the prescription and accompanying physician’s letter.
- Bring insect repellent and sunscreen.
- Defer travel while acutely ill.
- Consult www.cdc.gov/travel 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 in areas where outbreaks of vectorborne diseases, such as chikungunya and Zika, are occurring.
- Use sun protection.
- Maintain good fluid intake, but avoid excessive alcohol consumption.
- Avoid contact with ill people.
- If sexually active, practice safe sex.
- Report illness to ship’s infirmary and follow medical recommendations.
REPORTING ILLNESS AFTER TRAVEL
Travelers who become ill after returning home should inform their health care providers of where they have traveled. Clinicians should report suspected communicable diseases in recently returned cruise ship travelers to public health authorities:
- Report GI illnesses related to cruise ship travel to the CDC VSP by calling 800-CDC-INFO (800-232-4636) or by visiting www.cdc.gov and clicking on “Contact CDC-INFO”)
- Inform CDC of any travel-associated Legionnaires’ disease cases by sending an e-mail to email@example.com.
- Report communicable diseases to the public health authority of jurisdiction. Health departments should notify the CDC quarantine station of jurisdiction (www.cdc.gov/quarantine/quarantinestations.html) for communicable diseases of public health concern during travel.
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Krista Kornylo Duong, Kiren Mitruka, and Susan A. Lippold