Chikungunya Update for Clinicians

Joanna Gaines, PhD, MPH, MA, CHES


May 04, 2015

Editorial Collaboration

Medscape &

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From a single case introduced in the Caribbean in December 2013, chikungunya has rapidly spread across the Western Hemisphere and remains a risk to US residents traveling to tropical areas. I'm Dr Joanna Gaines with the Travelers' Health Branch at the Centers for Disease Control and Prevention. I am pleased to be speaking with you today as part of the CDC Expert Video Commentary series on Medscape.

Today I will be discussing the current state of chikungunya, the continued risk for importation into the United States, and the ongoing need to counsel travelers to the American tropics on how to avoid such mosquito-borne diseases as chikungunya.

Between December 2013 and March 2015, more than 1.2 million cases of chikungunya have been reported in 44 countries and territories throughout the Americas. Local transmission has been reported from almost every island in the Caribbean, all countries in Central America, several countries in South America, and parts of Mexico. In 2014, nearly 2500 cases of chikungunya were reported in the United States. Almost all were in returning travelers, with the exception of 11 locally transmitted cases in South Florida. The situation is likely to change. For the most up-to-date information, see CDC's chikungunya website and travel health notices.

There is no way to predict how long the outbreak in the Americas will last. Transmission may continue for years, with increases during the rainy season, from May through December. As with dengue, chikungunya could even become an endemic disease in tropical areas of the Western Hemisphere. Fortunately, because of the temperate climate and use of air conditioning (which keeps mosquitoes out of many homes), in most of the continental United States, sustained transmission is unlikely beyond South Florida and along the US-Mexico border.

US clinicians need to be aware of the ongoing risk for importation among people who have traveled internationally in the previous 2 weeks. Because dengue is also endemic throughout the Americas, both dengue and chikungunya should be included in the differential diagnosis of a traveler with an acute febrile illness and compatible travel history.

Whereas chikungunya is more likely to cause high fever, severe arthralgia, arthritis, rash, and lymphopenia, dengue is more likely to cause neutropenia, thrombocytopenia, hemorrhage, shock, and death. Co-infection with these viruses is possible and has been reported in previous outbreaks. Because these illnesses are clinically similar, acetaminophen should be used to manage pain in people suspected of having one of these illnesses (aspirin or nonsteroidal anti-inflammatory drugs can increase the risk of bleeding in people with dengue).

Chikungunya and dengue are both nationally notifiable conditions. Healthcare providers should report suspected chikungunya cases to their local or state health department to facilitate diagnosis and mitigate the risk for local transmission. People with chikungunya develop a high viremia and can infect local mosquitoes if they are bitten.

Travelers going to popular tourist and cruise destinations in the Caribbean and other areas where chikungunya is a risk may not seek a pre-travel consultation or volunteer their travel plans. Clinicians should use primary care visits as an opportunity to ask about upcoming travel, particularly for those patients who are known to be frequent travelers. Anyone planning travel to a tropical destination at any time of year should be counseled on the need to avoid mosquito bites.

General protective measures include:

  • Using an approved insect repellent when outside;

  • Wearing long-sleeved shirts and long pants and socks as much as possible; and

  • Staying in accommodations that are air conditioned or well screened.

The Aedes mosquitoes that transmit both chikungunya and dengue are aggressive daytime biters.

Certain travelers are at higher risk for more serious disease, including people with serious underlying medical conditions and people aged 65 or older. Pregnant women infected late in pregnancy are at risk of passing the virus to the newborn baby. People with arthritis appear to be at greater risk of developing persistent joint pain after chikungunya infection.

Until a vaccine or antiviral therapies are available to offer to travelers, the best advice you can provide to your patients to help them avoid mosquito-borne diseases such as chikungunya and dengue is to avoid getting bitten.

Best wishes for safe and healthy travel!

Web Resources

CDC: Chikungunya Virus

Chikungunya Traveler's Information

Differentiating Chikungunya From Dengue: A Clinical Challenge

Protection against Mosquitoes, Ticks, & Other Insects & Arthropods

Chikungunya in South America

Chikungunya in Central America

Chikungunya in the Caribbean

Chikungunya in Mexico

Lieutenant Commander Joanna Gaines, PhD, MPH, MA, CHES, is a senior epidemiologist with CDC's Travelers' Health Branch. LCDR Gaines received her bachelor's degree from Princeton University. She completed her PhD, MA, and MPH degrees at the University of Alabama at Birmingham, where she studied unintentional injury and violence. LCDR Gaines began her career at CDC in 2010 as an Epidemic Intelligence Service (EIS) Officer assigned to the Waterborne Disease Prevention Branch within the Division of Foodborne, Waterborne, and Environmental Diseases. She has also worked for the Indian Health Service in Anchorage, Alaska. LCDR Gaines enjoys studying a variety of pathogens and populations.