Cruise Ship Travel
Cruise travel continues to gain popularity. In 2010, the North American cruise industry, which makes up most of the global cruise market, comprised 205 ships that carried nearly 15 million passengers to destinations. Of these, almost 10 million passengers left from US ports, and Florida accounted for two-thirds of all US departures. The Caribbean is the top destination, followed by the Mediterranean, Europe, and Alaska. The average length of a cruise is 7 days, although voyages range from a few hours (“voyages to nowhere”) to several months for around-the-world cruises. An average-sized cruise ship carries 2,200 passengers; however, cruise ship capacities continue to increase, and “mega ships” can exceed 5,000 passengers. The crew-to-passenger ratio is roughly 1:2. The median age of a cruise ship passenger is 48 years, and more than one-quarter are ≥60. To a certain extent, cruise lines target different population groups, and longer cruises often attract older passengers.
Although most passengers on North American cruise ships are from the United States or Canada, 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 facilitates transmission of communicable diseases either person to person or from contaminated food, water, or environmental surfaces. Crew members who remain onboard can sustain transmission of infectious diseases. The stress of travel can worsen chronic conditions in specific groups, such as pregnant women and the elderly, who may also be more seriously affected by infectious diseases.
HEALTH AND SAFETY REGULATIONS
The World Health Organization’s International Health Regulations (IHR), which were revised in 2005 and implemented in 2007, provide international standards for ship and port sanitation, disease surveillance, and response to infectious diseases. The intent of the IHR (2005), binding in 194 countries, is to help the international community prevent and respond to acute public health risks worldwide, while avoiding unnecessary interference with international traffic and trade (www.who.int/ihr/en).
The US Coast Guard enforces safety, security, and environmental regulations in US waters and on the high seas. CDC ensures health and sanitation aboard ships with international itineraries arriving at US ports. US federal quarantine regulations require such ships to immediately report all shipboard deaths and certain illnesses suggestive of communicable diseases. CDC’s 20 quarantine stations respond to these reports, providing recommendations to prevent the spread of illness (www.cdc.gov/quarantine/index.html). Since 1975, CDC’s Vessel Sanitation Program (VSP) has also helped the cruise ship industry prevent and control gastrointestinal illnesses by inspecting cruise ships, monitoring gastrointestinal illnesses, and responding to outbreaks, updates of which are posted on its website (www.cdc.gov/nceh/vsp). Guidelines of Health Canada’s Cruise Ship Inspection Program (www.hc-sc.gc.ca/hl-vs/travel-voyage/general/ship-navire-eng.php) are harmonized with those of VSP.
CRUISE SHIP MEDICAL CAPABILITIES
Medical facilities on cruise ships can vary widely depending on a number of factors, such as ship size, itinerary, length of cruise, and passenger demographics. Generally, shipboard medical clinics are comparable to ambulatory care centers. Although no official agency regulates medical practice aboard cruise ships, consensus-based guidelines have been published, which cruise lines are encouraged to adopt. The Cruise Lines International Association (CLIA), representing 26 major cruise lines that account for >97% of the North American cruise market (www.cruising.org), developed industrywide guidelines in 1995 to promote the following standard of care among cruise ship medical facilities:
- 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
The American College of Emergency Physicians, Section of Cruise Ship and Maritime Medicine, provides more detailed Health Care Guidelines for Cruise Ship Medical Facilities (www.acep.org/practres.aspx?LinkIdentifier=id&id=29980&fid=2184&Mo=No). Recognizing that the needs of individual ships can vary, these guidelines describe desired physician qualifications (3 years’ postgraduate training in general and emergency medicine or board certification in emergency medicine, family practice, or internal medicine) and nurse competencies. They also outline recommended shipboard medical care capabilities, including medications, supplies, equipment (such as laboratory and x-ray) and preparedness planning.
ILLNESSES AND INJURY ABOARD CRUISE SHIPS
Cruise ship medical clinics deal with a wide variety of illnesses and injuries. Most health-related events are treated or managed onboard. However, evacuation and shoreside consultation for medical, surgical, and dental problems are not infrequent; 3%–11% of all conditions reported on a cruise ship are urgent or an emergency.
Published reviews of cruise ship medical logs have shown that most (69%–88%) passenger dispensary visits on cruise ships were due to medical conditions; respiratory (19%–29%) and gastrointestinal (9%) illnesses were the most frequently reported diagnoses. Injuries, typically from slips, trips, or falls, accounted for 12%–18% of medical visits.
Deaths on cruise ships are most often due to cardiovascular events. The most frequently documented cruise ship outbreaks involve respiratory infections (influenza and legionellosis), gastrointestinal 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, most ships conduct preembarkation medical screening followed by specific management of contagious passengers according to cruise line protocols and the medical judgment of onboard physicians. CDC guidance to cruise ships for commonly reported conditions (varicella, influenzalike illness) is available on the CDC Travelers’ Health website (wwwnc.cdc.gov/travel/page/travel-industry-cruise.htm). Passengers acutely ill with communicable diseases should delay travel until they are no longer contagious. Ill passengers are encouraged to use onboard medical facilities for optimal care and to maximize reporting of potential public health events.
SPECIFIC HEALTH RISKS
VSP conducts twice-yearly, unannounced inspections of ships carrying ≥13 passengers with international itineraries that call on US seaports. Cruise ships report to VSP the total number of cases of gastrointestinal illness evaluated by the medical staff before arrival at a US port. In recent years, outbreaks of gastroenteritis on cruise ships (defined as ≥3% of passengers or crew with reported symptoms of acute gastrointestinal illness during a voyage) have continued, despite good cruise ship environmental health standards and high VSP inspection scores. Most cruise ship gastrointestinal outbreaks are due to norovirus, which is also the leading cause of sporadic cases and outbreaks of gastroenteritis in the United States. 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. Vigilance in hand hygiene is key to reducing spread of norovirus (see Chapter 3, Norovirus).
Gastrointestinal outbreaks on cruise ships from food and water sources have been associated with Salmonella, enterotoxigenic Escherichia coli, Shigella, Vibrio, Staphylococcus aureus, Clostridium perfringens, Cyclospora, hepatitis E virus, and Trichinella.
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. Outbreaks usually result from the importation of influenza by embarking passengers and crew, followed by person-to-person spread.
During the 2009 influenza A (H1N1) pandemic, cruise line medical personnel made case-by-case decisions regarding the boarding of passengers with influenzalike illness. Travelers, particularly those at high risk for influenza-related complications, should receive the current seasonal influenza vaccine, if available, ≥2 weeks before travel. Cruise ships have the capacity to manage cases of influenzalike illness according to CDC recommendations (wwwnc.cdc.gov/travel/page/guidance-cruise-ships-flu.htm). Onboard control measures travelers can expect include isolation of ill people, encouragement of respiratory hygiene and cough etiquette, antiviral treatment of ill people, and prophylaxis of high-risk contacts.
Legionellosis (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. Symptom onset is typically 2–10 days after exposure, and older (≥65 years) travelers and those with underlying medical conditions are at increased risk for infection.
Contaminated ships’ whirlpool spas and potable water supply systems are the most commonly implicated sources of shipboard Legionella outbreaks, although improvements in ship design and standardization of spa and water supply disinfection have reduced the risk of Legionella growth and colonization. Most cruise ships can perform Legionella urine antigen testing. In evaluating returned travelers for Legionnaires’ disease, clinicians should collect respiratory secretions for culture, which is essential to identifying the source of infection, in addition to collecting urine for antigen testing. People with suspected Legionnaire’s disease require prompt antibiotic treatment.
About 20%–25% of all Legionnaires’ disease reported to CDC is travel-associated. CDC should be informed of any travel-associated Legionnaires’ disease cases by sending an e-mail to email@example.com.
Although each cruise ship voyage typically introduces a new cohort of passengers, crew members remain onboard for extended periods. And although most cruise ship passengers are from countries (mainly the United States and Canada) with routine vaccination programs, crew members tend to originate from developing countries, some with low immunization rates. In past cruise ship investigations involving vaccine-preventable diseases, 11% of crew members were found to be acutely infected with or susceptible to rubella, and 13% of crew, mostly from tropical countries, were susceptible to or acutely infected with varicella.
Crew members should have documented proof of immunity to vaccine-preventable diseases. Passengers should be up-to-date with routine vaccinations before travel, as well as any required or recommended vaccinations at 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, and yellow fever, are endemic. Yellow fever vaccination certificates may be required by some countries for entry. Although cruise lines may schedule arrival and departure times to avoid peak mosquito-biting periods, personal protection is still necessary. Preventive measures include the following:
• Using an effective insect repellent (see Chapter 2, Protection against Mosquitoes, Ticks, & Other Insects & Arthropods)
• Taking antimalarial chemoprophylaxis based on a destination- and activity-specific risk assessment (see Chapter 3, Malaria)
• Remaining in well-screened or air-conditioned areas
• Minimizing areas of exposed skin by wearing long-sleeved shirts, long pants, boots, and hats
Other Health Concerns
Stresses of cruise ship travel include varying temperature and weather conditions, as well as unaccustomed changes in diet and physical activity. Foreign travel increases 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 and likely unrelated to location of passenger cabins (see Chapter 2, Motion Sickness).
PREVENTIVE MEASURES FOR CRUISE SHIP TRAVELERS
Before and During Travel
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 6-01 summarizes recommendations for cruise travelers and clinicians advising cruise travelers in pre-travel preparation and healthy behaviors during 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. Gastrointestinal illnesses related to cruise ship travel should be reported to the CDC VSP (by calling 800-CDC-INFO [800-232-4636] or by visiting www.cdc.gov and clicking on “Contact CDC-INFO”). Clinicians should inform CDC of any travel-associated Legionnaires’ disease cases by sending an e-mail to firstname.lastname@example.org. Other suspected communicable illnesses should be reported to the CDC Quarantine Station with jurisdiction over the cruise ship’s port of arrival (www.cdc.gov/quarantine).
Box 6-01. Cruise travel health precautions
Advice for Clinicians Giving Pre-Travel 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 EKG 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 Chapter 2, Motion Sickness).
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 care providers before cruise travel.
- 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.
- Defer travel while acutely ill.
- Wash hands frequently with soap and water or use an alcohol-based sanitizer containing ≥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.
- Use sun protection.
- Maintain good fluid intake, but avoid excessive alcohol consumption.
- Avoid contact with ill people.
- If sexually active, practice safe sex.
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Douglas D. Slaten, Kiren Mitruka