According to the Cruise Lines International Association, 16.32 million passengers from North America* went on cruises in 2011 — an increase of 10 percent over 2010.

CLIA is composed of 26 of the major cruise lines operating in North America. Since 1980 it has seen an average annual passenger growth rate of 7.2 percent, making cruising the fastest-growing sector of the travel industry.

While CLIA touts cruising as a safe and affordable vacation option, it acknowledges passengers should do their part to reduce the risk of illness and injury.

"Cruisers should consult with their physician and be up to date on their routine vaccinations, including the flu," said Corinne Norfleet, a supervisor with Hono­lulu-based Panda Travel whose career as a travel consultant spans 32 years. "If they’re going to a foreign country, they should check the recommendations for other vaccinations and preventative measures against diseases such as malaria and yellow fever. The websites for the Centers for Disease Control and World Health Organization are good sources."

Norfleet also advises passengers to alert their travel consultant about allergies, special dietary requirements and the need for portable medical equipment, so proper arrangements can be made with the cruise line. In addition, she said, "When visiting foreign ports, you should be aware of the quality of the food and water. Most ships sell bottled water, which is a good thing to take on shore excursions. If you’re planning to take a tour in a forested area, be sure you have insect repellent."

Savvy cruisers buy travel insurance with emergency medical expense and evacuation coverage. "This is very important, especially if you’re going abroad," Norfleet said. "Many of our health insurance policies, including basic Medicare, don’t provide coverage outside the U.S., so if you wind up needing treatment or medical evacuation, the cost can run in the tens of thousands of dollars."

Factors that can affect the health of passengers on a cruise include weather, temperature, changes in diet and activity level, and exposure to a confined population that comes from a variety of communities and backgrounds. Cold, flu, seasickness, gastrointestinal infections and dental problems are among the common complaints.

Although no official agency regulates shipboard care, most vessels operated by CLIA members have medical centers that meet or exceed the standards set by the American College of Emergency Physicians, the nation’s leading and largest professional organization of such specialists. (Norfleet notes some riverboats might not have onboard clinics because they travel beside towns and cities and can call for medical assistance from shore.)

ACEP guidelines dictate, for example, that ships’ medical facilities include at least one inpatient bed per 1,000 passengers and crew. The staff of licensed doctors and registered nurses must be on call around the clock while the ship is at sea. Doctors should have three years of postgraduate clinical practice in general and emergency medicine or board certification in emergency medicine, internal medicine or family practice.

In addition, the clinic should have the supplies, equipment and medications needed to treat common medical emergencies. Ship size, itinerary and anticipated patient mix (e.g., a large number of seniors) determine specific needs.

AnneMarie Mathews, spokes­woman for Norwegian Cruise Line, which operates interisland cruises in Hawaii on the Pride of America, said passengers are asked to complete a health questionnaire at the embarkation terminal prior to checking in. If necessary, the medical staff will go to the terminal to examine anyone who displays symptoms of acute gastroenteritis (AGE), which include nausea, diarrhea, vomiting and stomach cramps. Usually caused by a viral infection, AGE is contagious.

"If it is determined passengers have symptoms of AGE," Mathews said, "they are given the option to sail but to stay in their stateroom until the doctor deems the danger of spreading the virus has passed, to meet the ship in the next port of call if they no longer have symptoms, or to cancel their trip and receive credit for a future cruise."

Fact sheets in NCL staterooms outline symptoms of concern and advise passengers what to do if they develop them. But Mathews believes they should take action long before they board a ship.

"People should consider their health and medical requirements when they’re deciding on the length and location of a cruise," she said. "Doing a realistic assessment and taking the proper precautions with input from their doctor will ensure they have a safe and enjoyable experience."