Kiren Mitruka

The continued popularity of cruise travel, along with the expansion of cruise itineraries to areas not easily accessible otherwise, promotes the exposure of travelers to multiple global destinations in a short period of time. Passengers and crew from around the world bring together a diversity of cultures, medical risk factors, and health risk behaviors.

• About 12 million passengers worldwide took a cruise vacation in 2007, a 7% increase over 2006.
• The North American cruise industry makes up the majority of the global cruise market and since 1980 has had an average annual passenger growth rate of 8.1%.
• U.S. ports handle about 75% of all embarkations.
• The Caribbean is the top cruise destination, followed by the Mediterranean, Europe, Alaska, and Mexico.
• A typical cruise is about 7 days long and includes 3,000 passengers and 1,000 crew members.
• Approximately 78% of cruise passengers are U.S. residents. About 50 nationalities are represented among crew members, most of whom are from developing countries.

Challenges of Cruise Ship Travel and Infectious Diseases

• Densely populated, semi-enclosed cruise ship environments may permit repeated and prolonged exposure to communicable diseases, resulting in their transmission between passengers and crew members.
• Differences in sanitation standards and disease prevalence between seaports may also lead to communicable disease exposure and spread.
• The risk of acquiring an infectious disease during cruise travel is difficult to quantify due to the diverse activities of crew and passengers, as well as the wide range of potential disease exposures.
• Senior citizens (an estimated one-third of cruise travelers) and travelers with underlying chronic health problems are at increased risk of illness from infections such as influenza, Legionella, and noroviruses.
• Early detection and prevention of infectious diseases are important, not only to protect the health of cruise travelers, but also to avoid global dissemination of diseases in home communities through disembarking passengers and crew members.

Medical Care Aboard Cruise Ships

Medical facilities on cruise ships can vary, depending on the size of the ship, its itinerary, number of crew and passengers, and the mean age and health status of passengers. The American College of Emergency Physicians (ACEP) Health Care Guidelines for Cruise Ship Medical Facilities is a consensus report on appropriate facilities and staffing requirements for basic shipboard medical and emergency services, given the recognized limitations of offshore environments. Shipboard health care recommended in these guidelines includes provision of—

• A medical infirmary with licensed medical staff (physician and registered nurse) on call 24 hours per day
• One intensive care unit (ICU) room
• One bed per 1,000 passengers and crew members
• One isolation room or the capability to isolate patients with communicable diseases
• Emergency and portable medical equipment, such as a bag valve mask, oxygen tank, endotracheal tube, defibrillator, and a cardiac monitor or external cardiac pacer
• Medications to handle medical emergencies
• Basic diagnostic and laboratory supplies for blood chemistry analyses, complete blood counts, urinalyses, chest x-rays, and electrocardiograms (EKGs)
• A medical record and communication system
• Health, hygiene, and safety program for medical personnel

Large cruise lines that operate in the United States or are members of Cruise Lines International Organization (CLIA) meet or exceed ACEP guideline standards. However, medical care on these ships should be equated to that of community urgent-care centers, not full-service hospitals. Small ships or those run by independent ship operators may not follow the ACEP guidelines. Therefore, on such ships, medical provisions might not be available onboard.

Primary Health Concerns on Cruise Ships

General

In a retrospective study of four cruise ship medical logs maintained by a major cruiseline, 7,147 new patient visits occurred among 196,171 cruise passengers on 172 voyages.

• Over half of shipboard infirmary visits are made by passengers over the age of 65.
• The most common diagnosis was respiratory tract infection (29.1%), followed by injuries (18.2%), seasickness (9.1%), and gastrointestinal (GI) illness (8.9%).
• An estimated 95% of illnesses seen in cruise ship medical facilities can be treated onboard. However, passengers with serious problems, such as myocardial infarction or cerebrovascular accidents, need to be transferred to shoreside hospitals after stabilization.

Communicable Diseases

Communicable diseases occurring onboard cruise ships are similar to those that occur onshore. Detecting illnesses of public health significance is aided by heightened cruise line surveillance efforts in cooperation with public health authorities, and passenger reporting.

• The most frequently documented cruise ship outbreaks involve respiratory infections (influenza and Legionella) and gastrointestinal infections (norovirus).
• In the past decade, clusters of illnesses due to vaccine-preventable diseases other than influenza, such as rubella and varicella (chickenpox), have also been reported.

Respiratory Illnesses

Influenza

• Outbreaks of influenza A and B can occur year-round, despite seasonality in the destination regions for cruises.
• Respiratory illness outbreaks usually result from the importation of influenza by embarking passengers and crew; the infection subsequently spreads person to person on the ship.
• Onboard control measures include isolation, infection control, and antiviral treatment of ill individuals as well as those exposed to the illness.
• One of the largest and most protracted influenza outbreaks occurred among land- and sea-based tourists to Alaska and the Yukon during the summer of 1998.

Legionnaires’ Disease

• Legionnaires’ disease has led to pneumonia outbreaks on multiple occasions, sometimes on consecutive cruises.
• Although contaminated ships’ whirlpool spas and potable water supply systems are the most commonly implicated sources of Legionella outbreaks, exposure to other sources may also occur during port stops.
• Pinpointing the source of these outbreaks has proved difficult because diagnoses in returned travelers may be delayed and clinical specimens may be unavailable for culture at the time of diagnosis.
• Culture-based diagnostic tests for cruise travel-associated Legionnaires’ disease are of public health importance.
• Improvements in ship design and standardization of spa and water supply disinfection have reduced the risk of Legionella growth and colonization.

Gastrointestinal (GI) Illnesses

The estimated likelihood of contracting gastroenteritis on an average 7-day cruise is less than 1%. GI illness accounts for fewer than 10% of shipboard passenger infirmary visits. In recent years, outbreaks of gastroenteritis on cruise ships have increased, despite good cruise ship environmental health standards.

Noroviruses

• The increase in gastroenteritis on cruise ships is primarily attributed to noroviruses, also the main cause of acute viral gastroenteritis in the United States.
• Large, consecutive cruise ship outbreaks have resulted from noroviruses, due to their—
  • low infective dose,
  • easy person-to-person transmissibility, and
  • ability to survive routine cleaning procedures.
• Prompt implementation of disease control measures, such as the isolation of ill persons, strict application of food and water sanitation measures, and disinfection of surfaces with suitable disinfectants, are key to controlling norovirus outbreaks.

Other pathogens

Other known causes of GI illness clusters on cruise ships include food or water contaminated with Salmonella spp., enterotoxigenic Escherichia coli, Shigella spp., Vibrio spp., Staphylococcus aureus, Clostridium perfringens, Cyclospora sp., and Trichinella spiralis.

Vaccine-Preventable Diseases on Cruises

Other than influenza, clusters of rubella and varicella have been investigated on cruises originating in the United States, highlighting the potential global dissemination of vaccine-preventable diseases through cruise travel.

• During a cruise ship outbreak investigation of rubella, 11% of the crew was found to be acutely infected with or susceptible to rubella and 33% of passengers onboard were women of childbearing age—a high-risk group for congenital rubella syndrome if infected during pregnancy.
• One investigation of varicella outbreak aboard a cruise ship found that 13% of the crew, most foreign-born from tropical countries, were either acutely infected or susceptible.
• Vaccine administration to crew members without documented immunity to vaccine-preventable diseases and notification of all passengers at risk for exposure serve as important control measures.

Other Health Concerns

Injuries

• Are among the most common reasons for passengers to seek medical care on cruise ships.
• Account for about 18% of passenger infirmary visits.
• Occurring most frequently on cruise ships include sprains, contusions, and superficial wounds.

Seasickness

• Is also a common reason for cruise passenger infirmary visits.
• May not be reduced by the central location of a cabin.
• See the Motion Sickness section in Chapter 2 for more information.

Exacerbation of Chronic Conditions

• Cruise ship travelers with chronic health conditions may experience complications due to—
  • Climatic variations
  • Environmental exposure to pollutants
  • Changes in diet and physical activity levels
  • An increased level of stress due to being in an unfamiliar environment
• Special cruises are available for travelers with certain medical conditions, including persons on dialysis.

Preventive Measures for Cruise Ship Travelers

Due to multiple port visits and potential exposures, cruise ship travelers may be uncertain about which prevention medications, immunizations, and behaviors are appropriate for them and for their itineraries. Pre-travel advice for cruise ship travelers should include a complete review of the health status of the traveler, duration of travel, countries to be visited, and shore side activities. Box 6-1 summarizes recommendations for cruise travelers and health-care providers advising cruise travelers in pre-travel preparation and healthy behaviors during travel.

After Travel

Health-care providers can contribute to healthy cruise ship environments by questioning ill returned travelers about recent cruise vacations and promptly reporting any suspected communicable disease to public health authorities.

Contacts for concerns about illnesses on cruise ships:

• GI illnesses concerns should be directed to CDC Vessel Sanitation Program—
  • Phone: 800-CDC-INFO (800-232-4636)
  • E-mail: CDCINFO@cdc.gov
• Other illnesses suggestive of a communicable disease should be reported to the nearest CDC quarantine station with jurisdiction nearest to the cruise ship’s port of arrival.

References

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2. Maloney SA, Cetron M. Investigation and management of infectious diseases on international conveyances (airplanes and cruise ships). In: Dupont HL, Steffen R, editors. Textbook of travel medicine and health. 2nd ed. Hamilton, Ontario: BC Decker; 2001. p.519–30.
3. Cruise Lines International Association (CLIA). Cruise Industry Overview—Marketing Edition 2005. [cited 1998 Aug 6]. Available from: http://www.cruising.org/press/overview/ind_overview.cfm.
4. Cruise Lines International Association (CLIA). About CLIA.[cited 2008 Aug 6]. Available from: http://www.cruising.org/about.cfm.
5. CDC. Rubella among crew members of commercial cruise ships—Florida, 1997. MMWR. Morb Mortal Wkly Rep 1998;46 (52):1247–50.
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9. ACEP. Healthcare Guidelines for Cruise Ship Medical Facilities. [cited 2008 Aug 6]. Available from: http://www3.acep.org/practres.aspx?id=29980.
10. Wheeler RE. Travel health at sea: cruise ship medicine. In: Zuckerman JN, editor. Principle and practices of travel medicine. New York: John Wiley and Sons; 2001. p. 275–87.
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12. CDC. Vessel sanitation program. [cited 2008 Aug 6]. Available from: http://www.cdc.gov/nceh/vsp/.
13. Cramer EH, Blanton CJ, Blanton LH, et al. Epidemiology of gastroenteritis on cruise ships, 2001–2004. Am J Prev Med. 2006;30(3):252–7.
14. Uyeki TM, Zane SB, Bodnar UR, et al. Large summertime influenza A outbreaks among tourists in Alaska and the Yukon Territory. Clin Infect Dis. 2003;36(9):1095–102.
15. Public Health Agency of Canada. Statement on cruise ship travel. Canada Communicable Disease Report 15 October 2005: 31-ACS—8 and 9. [cited 2008 Nov 29]. Available from: http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/05pdf/acs-dcc310809.pdf (PDF).
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17. CDC. Quarantine station jurisdictions and contact information. [cited 2008 Aug 6]. Available from: http://www.cdc.gov/ncidod/dq/resources/Quarantine_Station_Contact_List.pdf (PDF).