February 4, 1999
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.
