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Is Dengue Fever on the Rise in the U.S.?


In the confirmed cases of dengue, 56% were second infections, 11% were the person's first infection, and the remainder were indeterminable due to a lack of necessary laboratory tests. Of the confirmed cases, 39% had hemorrhagic manifestations. Also, of the confirmed cases, all had traveled from countries within 10 days of the onset of illness: six patients had traveled from Haiti, three from Puerto Rico, two from Columbia, two from Venezuela, one from Barbados, one from Nicaragua, and one from Thailand.

Usually, the viremic period -- time that the virus circulates in the blood stream -- is only four days, according to Gill. "One of the theories has been that it would be very difficult to import the disease and have local mosquitoes pick it up and start local transmission because the viremic period was so short," she says. "The theory was that, by the time people traveled back into the state, perhaps they would not be viremic anymore. But we were able to isolate virus from individuals while they were in the state of Florida, and that demonstrates that the risk of future transmission is there."

Is it possible that dengue fever will start to spread within Florida and to other states? Yes, says Gill. "The last time dengue was ... [a problem] in Florida was in the 1930s," she says. "There were big outbreaks in Tampa and Miami. There hasn't been any local transmission documented since then. [But,] certainly, individuals and mosquitoes that could be infected are coming in and out of the state regularly. The incidence of dengue in the surrounding countries is increasing dramatically."

Gill says that the incidence of dengue fever is probably a lot higher than that detected in this study. The majority of dengue illnesses have flu-like symptoms or no symptoms at all, so probably only the sickest people sought medical care, she says.

What is the solution? Patients traveling to countries where dengue fever is present need to protect themselves from mosquito bites by wearing protective clothing and using mosquito repellent, according to Gill. They need to see a physician if they become sick after returning home. When diagnoses of dengue are confirmed, patients need to protect themselves from mosquito bites for the period that they are sick, she says. "During that four-day period when they may be viremic, they need to protect themselves from mosquitoes so the mosquitoes don't bite them, pick up the virus, and possibly transmit it to other people," she says.

Vital Information:

  • Dengue fever is a virus transmitted via mosquitoes that can cause intense "bone-breaking" pain, and though recovery takes only a few days, related fatigue can last a month or two.
  • A new report shows that the incidence of dengue fever in Florida is higher than previously suspected.
  • When traveling to countries where dengue fever is a concern, one should wear protective clothing and insect repellent.

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