Outbreak of Acute Respiratory Illness Aboard Cruise Ships With Ports of Call in the Caribbean

The following alert is based on communications received from the Quarantine Division of the US Centers for Disease Control and Prevention [CDC] on January 28, 1999.

Since January 22, the Quarantine Division of the US CDC has been notified of significantly increased morbidity due to acute febrile respiratory illness both among the passengers and crew of three cruise ships that have ports of call in the Caribbean. Attack rates, among the passengers and crew aboard one of these ships, were recorded at 7 and 6 percent, respectively, over the 11-day cruise.

These cruise ships belong to three different cruise lines and our information indicates that the itinerary for one of these cruise ships includes ports in St. Thomas, US Virgin Islands; St. Christopher [Kitts]; Trinidad and Tobago; and Aruba.

While the symptom profile is predominantly one of an upper respiratory tract infection, a few cases of febrile pneumonia have been reported. The CDC has indicated that the length of the incubation period together with the symptom profile is suggestive of influenza infection. Diagnostic testing of nasopharyngeal swabs using a rapid antigen detection kit has yielded positive results for influenza A aboard one ship.

Both influenza A and B viruses are currently circulating in the United States and the CDC has recently reported the occurrence of widespread influenza activity in New York city [MMWR: January 22, 1999]. Influenza A (H3N2) viruses have been predominant and these strains have been found to be antigenically similar to A/Sydney/5/97, the H3N2 component of the 1998-1999 influenza vaccine. All of the influenza B viruses are antigenically similar to B/Beijing/184/93, the recommended type B vaccine strain.

The use of antiviral agents such as amantidine and rimantadine may help to prevent and control influenza A but not influenza B, especially among persons in institutional settings such as nursing homes and those at high risk for influenza–related complications. These drugs are 70-90 % effective in preventing influenza A infections and reducing the severity and duration of symptoms when administered within 48 hours of onset of illness. Influenza vaccination, if available, is recommended for high-risk persons.

It should be noted that the potential for introduction and spread of influenza viruses in the Caribbean is real at this time, given that December to April represents the height of the Caribbean tourist season. Added opportunity is also provided, as some islands will attract large numbers of overseas visitors for their upcoming Carnival celebrations.