Overseas travelers are advised to get their vaccinations before departing, and a study from the GeoSentinel Surveillance Network illustrates why. Ten years of data collected from 31 GeoSentinel travel and tropical medicine clinics on six continents were analyzed to assess how often ill returned travelers cited fever as their main reason for seeking care and what the causes of their illnesses were. According to the authors, learning where a febrile patient traveled and the length of the interval between her or his return and presentation at the clinic are important clues to determining the cause of the fever.

Of 24,920 patients who visited the clinics during the 10-year period, 28% sought care primarily because of fever. More than a quarter of febrile patients were hospitalized, whereas only 3% who didn't have fever were admitted. The travelers most likely to develop fever were those who went to sub-Saharan Africa, south-central Asia, or Latin America to visit friends and relatives. Malaria, diagnosed in 21% of those with fever, was the chief source of febrile illness and the cause of four of the 12 deaths that occurred among febrile patients. Other causes of fever included dengue, rickettsiosis, and influenza. In 22% of the returned travelers, no cause for the fever could be identified. More than 17% of the febrile illnesses could have been prevented if the travelers had undertaken malaria prophylaxis or vaccinations before traveling, underscoring lead author Mary E. Wilson's contention that "nurses play a key role in advising travelers on potential risks and recommending ways to reduce the risk of infections."

Determining the length of time between the traveler's return and presentation at a clinic with symptoms of illness is helpful in making a proper diagnosis. The incubation period for most infections is less than 30 days, but some, such as malaria and tuberculosis, take longer to produce symptoms. "The most important question to ask a febrile patient," says Wilson, "is 'Have you traveled recently to a tropical or subtropical area?' If there answer is yes, ask the patient for details.'"

Carol Potera