Science, Tech & Environment

After a long journey from Africa, a new tropical disease sets up shop in Florida

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Credit: Marie Arago/Reuters

Hatian Marqui Ducarme was hit with the Chikungunya virus in May of this year. After spreading quickly through the Caribbean, public health officials in Florida say the painful mosquito-borne disease has just shown up for the first time in the United States.

It can't kill you, or make you bleed from the eyes and ears the way the horrible Ebola virus that’s been ravaging West Africa can.

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But the chikungunya virus can cause such extreme joint pain that you can't even sit up for weeks.

There’s no cure or vaccine. And now the disease has established a beachhead in the United States.

This month, health authorities in Florida identified what they say are the first two cases of the nasty disease that were clearly acquired in the US.

Chikungunya is transmitted by mosquitoes and has been slowly expanding around the tropics and subtropics from southern Africa over the past 50 years or so. It began knocking on the door of the US late last year when it caused a major outbreak in the Caribbean.

Hundreds of cases have been spotted in the US but until this summer all of those had been contracted outside the country.

“What makes [these two new cases] really worrisome for public health officials,” says journalist Carrie Arnold, “is that it appears that the virus is now in the local mosquito population, Aedes aegypti, which is the species of mosquito that's transmitting virus in the Caribbean.”

Arnold has been covering the chikungunya story for NOVA Next, a news site from the PBS science program NOVA.

She says the symptoms are similar to dengue fever, which can be transmitted by some of the same mosquitoes. The name of the disease derives from a local southern African word meaning “that which bends over,” describing the kind of pain it can leave its sufferers in.

Now that the disease seems to have been naturalized into at least some south Florida mosquitoes, Arnold says officials are worried about the possibility of a much larger outbreak “because anyone who is bitten by this Aedes aegypti mosquito is vulnerable to the disease.”

And in fact, Arnold says she just read reports of a third case in the region, unrelated to the first two.

Still, she says, it’s unlikely that chikungunya will spread quickly within or beyond Florida.

“Most of the researchers that I talked to have been predicting small, localized outbreaks,” Arnold says, “not the big outbreaks you’re going to see with, say, West Nile, where it just spread across the country in a massive wave.”

She says that’s because, for now, anyway, the host mosquito Aedes aegypti is located only in limited areas of southern Florida and the south Gulf coast.

The impact of climate change may well be a concern in the future, Arnold says, as warming temperatures open up new habitat to the mosquito. But she says a bigger short-term concern is the spread of the mosquito by human travel and trade.

As for what measures can be taken to reduce the spread and impact of the disease, Arnold says there aren’t a lot of options. Florida officials are working on mosquito control measures like insecticides and reducing sources of standing water in which mosquitoes can breed. But she says some of the bugs can breed in as little as a tablespoon of water, “which makes eliminating all water sources where it can breed really, really difficult.”

And for now, Arnold says, there are really just three options for treatment: “fluids, rest and painkillers.”

  • hovering-mosquito-1024x576.jpg

    Credit: James Gathany/CDC

    Like many tropical diseases, chikungunya is spread by mosquitoes like this one. In July, Florida public health officials announced the first cases of chikungunya transmitted by mosquito in the U.S.

  • Emd-5577.jpg

    Credit: Wikimedia Commons/Cryoelectron microscopy reconstruction of chikungunya virus. From Electron Microscopy Data Bank (EMDB) entry EMD-5577

    The chikungunya virus is transmitted from person to person by some tropical species of mosquitoes. Actual size is 5 angstroms, or .0000001 millimeters in diameter.

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