Dengue Fever Reemerges in Florida After 75 Years


ATLANTA — An estimated 5% of the Key West, Fla., population—more that 1,000 people—showed evidence of recent exposure to dengue virus in 2009, according to the Centers for Disease Control and Prevention and the Florida Department of Health.

Dengue is the most common mosquito-transmitted virus and causes 25,000 deaths each year, according to the CDC. From 1946 to 1980, no cases of dengue acquired in the continental United States were reported, and there has not been an outbreak in Florida since 1934.

These cases represent the reemergence of dengue fever in Florida (and elsewhere in the United States) after 75 years, Dr. Harold Margolis, chief of the dengue branch at CDC, said at the conference.

After three locally-acquired cases of dengue fever were initially reported in 2009, scientists from the CDC and the Florida Department of Health conducted a study to estimate the potential exposure of the Key West population to dengue virus.

Since 1980, a few locally acquired U.S. cases have been confirmed along the Texas-Mexico border, which coincided with large outbreaks in neighboring Mexican cities. In recent years, there has been an increase in epidemic dengue in the tropics and subtropics, including in Puerto Rico, the CDC reported. On Sept. 1, 2009, a New York state physician notified the Monroe County (Fla.) Health Department and FDH of a suspected dengue case in a New York state resident whose only recent travel had been to Key West. In the next 2 weeks, two dengue infections in Key West residents without recent travel were confirmed. By the end of 2009, 27 cases had been identified.

In a poster presented at the conference, a total of 240 blood samples were collected from randomly selected households in Key West and tested for the presence of virus or evidence of a previous dengue infection. Among the samples, 4.95% had dengue active in their systems or had dengue antibodies. The strain was similar to strains from Mexico, according to study investigator, Glen Gallagher, of the CDC's dengue branch in Puerto Rico.

The take-away for physicians is that dengue fever can be a potential diagnosis even in patients without a history of travel, he said in an interview.

The CDC and the FDH continue to monitor cases in and around Key West. As of the end of June 2010, there had been 12 additional cases of locally-acquired dengue infections, bringing the total to 39.

Disclosures: Mr. Gallagher reported that he had no conflicts.

Evidence of dengue or its antibodies was detected in 4.95% of 240 blood samples in Key West.


The dengue virus, transmitted by the Aedes aegypti mosquito, causes 25,000 deaths annually.

Source Courtesy CDC/James Gathany

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