Chikungunya Virus Outbreak Likely in the U.S.

Chikungunya (pronounced chik-en-gun-ye) is a viral disease transmitted to humans by the bites of infected Aedes aegypti and Aedes albopictus mosquitoes, which are found across the globe. First described during an outbreak in southern Tanzania in 1952, the virus then spread to Africa, Asia, and the Indian subcontinent.

Originally believed to be a “tropical” disease, experts were surprised when an outbreak occurred in northeastern Italy in 2007. Now it has spread farther—to 14 Caribbean island countries since it was first detected on the island of St. Martin in December 2013. On May 1, 2014, the Caribbean Public Health Authority declared it an epidemic, with 4,108 probable cases across the region.

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Symptoms, Diagnosis, and Treatment of Chikungunya

The most common symptoms of chikungunya are acute, high fever and intense joint pain. The infected person may also experience headaches, muscle pain, swollen joints, and/or a rash.

According to the U.S. Centers for Disease Control and Prevention (CDC), chikungunya infection should be considered as a possibility in anyone who develops a high fever and joint pain, and who has traveled to the location of an active outbreak within the previous three to seven days.

A blood test is used to diagnose chikungunya and to differentiate it from dengue, a more serious viral infection, which is also transmitted by Aedes mosquitos. Outbreaks of dengue usually occur in tropical urban areas, according to the CDC.

"People should prevent mosquito bites by using adequate clothing, applying repellent, and getting rid of potential mosquito breeding sites."

Even though chikungunya symptoms can be severe, the disease is rarely fatal, unlike dengue, which can be lethal if not treated in a timely manner. Most patients with chikungunya begin feeling better within a week; a few may experience joint pain for several months. Some cases result in persistent arthritis symptoms. People at risk for more severe cases of the disease include newborns, adults over the age of 65, and patients with underlying medical conditions.

There is no cure for chikungunya, and no vaccine to prevent it, so treatment is focused on relieving the symptoms. An infected person needs to rest, drink lots of fluids, and take medicines like ibuprofen, naproxen, or acetaminophen to relieve fever and pain until the symptoms fade.

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Mosquitoes May Spread the Virus to the Southeastern U.S.

Because the Caribbean islands are close to the U.S., there is some concern that chikungunya will spread to the U.S., perhaps via Florida.

The disease has been diagnosed in the U.S. before, but only in travelers returning from areas where there are outbreaks, according to the Center for Infectious Disease Research and Policy. So far, no U.S.-based infections have occurred. But Dr. Gio J. Baracco, an associate professor of clinical medicine at the University of Miami Miller School of Medicine, told Healthline that the mosquitoes spreading the virus are already in the southeastern part of the U.S. “This fact, and the large amount of travelers passing through South Florida en route to and from the Caribbean islands, makes it very likely that chikungunya will be introduced into the U.S.,” he said.

Another infectious disease expert, Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University, explained how this “spreading” might occur. “Patients can acquire the infection while in the Caribbean through mosquito bites, and be incubating the infection. They’re feeling well as they come to the U.S. and then when they get sick, the virus is circulating in their blood streams.”

Then, an Aedes mosquito could bite that person and become infected itself, said Schaffner. “The mosquito thus infected in the U.S. infects another U.S. person, and that person in turn infects further mosquitoes. That’s how the virus appeared for the first time in a temperate zone, in Italy in 2007." 

The virus could be carried beyond Florida, Schaffner said, but he added, “It might be established more readily in Florida, partly due to the volume of travel.”

Dr. Aileen M. Marty, a professor of infectious diseases at the Herbert Wertheim College of Medicine in Miami, agreed. “It can spread to any part of the U.S. where the mosquitoes live and breed,” she said.

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Although an outbreak may occur at any time, Baracco said that summer is a vulnerable time. “The likelihood of an outbreak is related to the amount of vectors [infected mosquitoes] present. Aedes mosquitoes breed in stagnant water, and therefore are more common during the rainy season.”

The CDC's Dr. Erin Staples told Healthline that although it’s not possible to say at this point when local cases may occur here, it becomes more likely as more travelers return from areas where there are currently outbreaks, as mosquito populations grow, and as the weather gets warmer.

How Can I Protect Myself from Chikungunya?

To avoid becoming infected, Baracco said, “People should prevent mosquito bites by using adequate clothing, applying repellent, and getting rid of potential mosquito breeding sites."

Business travelers and vacationers in the Caribbean should exercise extra caution, Schaffner added. “Cruise travelers and people who stay in the islands for a period of time will need much more awareness about the prevention of mosquito bites. Use repellant—especially if you go out in the evening or in the early morning, when most of these mosquitoes like to bite. Wear longer trousers and long sleeves.”

Schaffner also envisions a wider use of bed netting. “People like to go to the islands, open the windows, and let the Caribbean breezes come through—they’re not always in hermetically sealed, air conditioned rooms. If you do that now, you might have to sleep under a bed net.”

The CDC is taking several steps to educate travelers to the Caribbean about the risks of chikungunya and how to protect themselves. Staples explained, "We are continually updating our travel notice with the latest on the spread of the virus and recommendations to prevent infection. In addition, the CDC has been working with its partners at airports with flights to the Caribbean to educate outgoing travelers about how to stay safe from chikungunya while in the Caribbean, and returning travelers about what symptoms to watch for and when to seek care. We’re also working to post them at additional airports and to translate them into Spanish."

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