Cruise Ships: High-Risk Passengers and the Global Spread of New Influenza Viruses

Abstract

In 1997, passengers on North American cruises developed acute respiratory illnesses (ARIs); influenza was suspected. We reviewed 1 ship's medical records for 3 cruises: cruise 1 (31 August to 10 September 1997), cruise 2 (11-20 September 1997), and cruise 3 (20-30 September 1997). Medically attended ARI was defined as any 2 of the following symptoms: fever (temperature, > or =37.8 degrees C) or feverishness, sore throat, cough, nasal congestion, chills, myalgia, and arthralgia. During cruise 2, we collected nasopharyngeal swabs for viral culture from people with ARI and surveyed passengers for self-reported ARI (defined as above except feverishness was substituted for fever). The outbreak probably began among Australian passengers on cruise 1 (relative risk, 3.3; 95% confidence interval, 1.89-5.77). Of 1284 passengers on cruise 2, 215 (17%) reported ARI, 994 (77%) were aged > or =65 years, and 336 (26%) had other risk factors for respiratory complications. An influenza strain not previously identified in North America was isolated. We concluded that an "off-season" influenza outbreak occurred among international travelers and crew on board this cruise ship.

Prevention and Control of Seasonal Influenza with Vaccines

“…In the tropics, influenza occurs throughout the year. Travelers can be exposed to influenza when travelling to an area where influenza is circulating, or when traveling as part of large tourist groups (e.g., cruise ships) that include persons from areas of the world in which influenza viruses are circulating (445,446). In a survey among Swiss travelers to tropical and subtropical countries, influenza was the most frequently acquired vaccinepreventable disease (447).…”

Recent advances and new challenges in travel medicine

“…Cruise ships provide the setting where persons from all over the world congregate, share closed spaces for eating and entertainment, and then disperse to home or other countries. Cruise ships may carry more than 2000 passengers and many have a high percentage of persons who are elderly and who have underlying chronic medical problems [52]. Summertime outbreaks of influenza have been seen in travelers to Alaska [53].…”

“…Summertime outbreaks of influenza have been seen in travelers to Alaska [53]. In August-September 1997, an outbreak of influenza A on a cruise ship traveling from New York to Montreal began among passengers from Australia, who were probably the source of an influenza strain A/Sydney/5/97, not previously identified in North America [52]. Peak influenza season in the Southern Hemisphere is April to September.…”

Benefits of influenza vaccination among healthy and high-risk persons across the age spectrum

“…Recent reports of influenza outbreaks related to air travel [13,14], cruise ships [15,16] and nosocomial transmission of influenza [17] highlight other important downstream effects of influenza. The surge in demand for medical care during epidemics can also overwhelm the capacity of the health care system [18,19].…”