54. CRUISE SHIPS

Traveling on a cruise ship should be a relaxing, enjoyable experience. Unfortunately, cruise ship travelers may have to contend with more than seasickness and sunburn. With thousands of people in the confined space of these floating cities, some health issues that are common on dry land can get out of control on the high seas.

Worldwide, cruise ships host approximately 23 million passengers each year, with Carnival (21.3%) and Royal Caribbean (16.7%) lines hosting the most travelers. In the United States, passengers tend to be older, as people 50–59 years old and 60-plus years old are 22% and 26% of all cruise ship passengers, respectively. Older travelers and those with underlying health issues may be at increased risk for contracting infections and suffering from injuries (e.g., falls) during a cruise.

Travelers usually are not concerned about a cruise ship sinking, but some are worried that they may catch a virus that hitches a ride on the cruise. In addition to the common cold virus, noroviruses can spread quickly throughout a cruise ship. Noroviruses are the source of most nonbacterial gastroenteritis infections (the stomach flu). Gastroenteritis typically causes symptoms such as vomiting, diarrhea, abdominal cramps, headache, fever, and muscle aches that usually last one to three days. Norovirus usually isn’t dangerous, but it is unpleasant. It’s probably not how you want to spend your honeymoon. Treatment for gastroenteritis involves managing symptoms of the illness and could include drugs to control diarrhea and vomiting. Dehydration should also be prevented by drinking nonalcoholic fluids.

Norovirus spreads through person-to-person contact and in aerosolized particles when someone coughs or sneezes. Any surface that comes in contact with the virus can transmit the virus to someone who touches it. The lounge chair, buffet spoon, slot machine handle, shuffleboard paddle, and anything else on the ship can potentially transmit disease. Although ships may be cleaned, it is not possible to disinfect every inch of a large cruise liner and kill the norovirus where it is hiding.

Fortunately, the CDC’s Vessel Sanitation Program (VSP) works with the cruise ship industry to reduce the risk of gastrointestinal illnesses on cruise ships. The VSP has jurisdiction over all ships with a U.S. port that carry 13 or more passengers and have a foreign itinerary. These vessels are inspected unannounced at least twice each year. The SHIPSAN ACT has a similar function for controlling diseases on ships cruising waters in the European Union. During an inspection, VSP inspectors check a ship’s (1) medical facilities to ensure medical logs and documentation of illnesses are in order; (2) potable water systems; (3) swimming pools and whirlpool spas for proper filtration, disinfection, safety, and maintenance; (4) galleys and dining rooms for suitable food protection, employee health, and hygiene; (5) child activity centers for properly equipped diaper-changing stations, toilets, and disinfection facilities; (6) hotel accommodations for proper infection control procedures; (7) ventilation systems; and (8) common areas for pest management, cleanliness, and maintenance. Inspected ships are scored on a 100-point scale, with a minimum of 86 points necessary for a passing grade. Passengers can check the scores of specific vessels on the CDC VSP website. When an outbreak of a gastrointestinal illness occurs on a cruise ship, the VSP works with the ship’s crew to determine the cause and magnitude of the illness and to develop a plan to contain and stop the illness. The VSP can also ask cruise lines to notify port authorities about the outbreak and to delay a ship’s next voyage.

In 2016, the CDC reported 13 outbreaks of gastrointestinal illness on international cruise ships participating in the VSP. Of these 13 outbreaks, 10 were caused by norovirus alone, one by combined norovirus and E. coli bacteria, one by E. coli alone, and one by an unknown agent. In some of these incidents, 10% of all passengers on board had symptoms (vomiting, diarrhea) of gastroenteritis. Given the large number of passengers who travel on these cruise ships, the likelihood of contracting acute gastroenteritis is small. According to a CDC report, of the 73.6 million passengers and 28.3 million crew members who sailed between 2008 and 2014 on cruise ships under the VSP, only 129,678 passengers and 43,132 crew members contracted acute gastroenteritis. This is equivalent to only 0.18% of passengers and 0.15% of crew members. Almost all (92%) of the illnesses were caused by norovirus.

Outbreaks of other infectious diseases such as rubella, chicken pox, hepatitis, and Legionnaires’ disease have also been reported on cruise ships. For example, in 2008, passengers returning to the United Kingdom after a cruise around the world were affected by an acute hepatitis E infection likely caused by contaminated food. A total of 83 cases of Legionnaires’ disease (six deaths) have been linked to cruises taken between 1977 and 2012.

Cruise ship passengers face special health challenges depending on their destination. For example, people traveling to parts of Asia, the Caribbean, Africa, and Central America may be exposed to mosquitoes that carry dengue fever, malaria, chikungunya disease, and Zika virus. Travelers on shore excursions to various locations should also be cautious of water and raw food contaminated with bacteria and viruses.

The best way to stay healthy on a cruise is to have good hygiene practices. Wash your hands with soap and warm water frequently, especially before all meals and after using the bathroom. Alcohol-based hand sanitizers can also be used if running water is not available. To reduce the spread of contamination by person-to-person contact, Eilif Dahl of the Norwegian Centre for Maritime Medicine suggests using a fist bump instead of a handshake as a greeting on cruise ships. Passengers traveling to areas with mosquitoes and other bugs should apply insect repellents and wear long sleeves and long pants to reduce the chance of bites. The risk of contracting an illness from contaminated food and water can be reduced by eating only cooked food and peeled fruits and vegetables and drinking beverages from sealed packages without ice. Finally, it is a good idea to pack your own first aid kit, because a ship’s medical facility may not stock the supplies you need.

SUMMARY

Preventability (98)

No one needs to take a cruise; there are many other ways to travel.

Likelihood (14)

Cruise ships can harbor infectious pathogens, but most cruise ships travel from port to port without a problem.

Consequence (37)

Contracting an infectious disease on a cruise ship can spoil your vacation or possibly send you to the hospital.

REFERENCES

Centers for Disease Control and Prevention. (2017, July 18). About the Vessel Sanitation Program. Retrieved from https://www.cdc.gov/nceh/vsp/desc/aboutvsp.htm

Cruise Market Watch. (2017). Growth of the ocean cruise line industry. Retrieved from http://www.cruisemarketwatch.com/growth/

Dahl, E. (2016). Cruise tap versus handshake: Using common sense to reduce hand contamination and germ transmission on cruise ships. International Maritime Health, 67, 181–184.

Freeland, A. L., Vaughan, G. H., Jr., & Banerjee, S. N. (2016). Acute gastroenteritis on cruise ships—United States, 2008–2014. MMWR, Morbidity and Mortality Weekly Reports, 65, 1–5. doi:http://dx.doi.org/10.15585/mmwr.mm6501a1

Mouchtouri, V. A., & Rudge, J. W. (2015). Legionnaires’ disease in hotels and passenger ships: A systematic review of evidence, sources, and contributing factors. Journal of Travel Medicine, 22, 325–337.

Said, B., Ijaz, S., Kafatos, G., Booth, L., Thomas, H. L., Walsh, A., Ramsay, M., & Morgan, D. (2009). Hepatitis E outbreak on cruise ship. Emerging Infectious Diseases, 15, 1738–1744.

SHIPSAN ACT. (n.d.). Retrieved from http://www.shipsan.eu/