The chikungunya (pronounced chik-en-gun-ye) virus is transmitted to humans by mosquitoes that become infected when they feed on a person who has the virus, often causing large outbreaks. Originating in East Africa, chikungunya outbreaks commonly occur in Africa, Asia, Europe and the Indian and Pacific ocean regions. In late 2013, the first local transmission in the Americas was reported in the Caribbean.

First identified in southern Tanzania in 1952, the virus caused sporadic cases in Africa and large urban outbreaks in Thailand and India during the 1960s and 1970s. In 2004, a large outbreak on the Kenyan coast further spread throughout the islands of the Indian Ocean, India and parts of Southeast Asia. Traveler-related cases introduced the virus into Italy and France, resulting in local transmission and several hundreds of cases in Europe. Aedes mosquitoes transmit the virus; they are aggressive and bite mostly during the daytime. Chikungunya is a single-strand RNA virus, with humans the primary hosts during epidemics.

The incubation period after exposure is usually three to seven days (the range is one to 12 days). Most people experience an acute onset of fever and pain in several joints. Joint symptoms, often severe and debilitating, are usually symmetrical and often occur in hands and feet. Other symptoms include headache, arthritis, muscle pain, conjunctivitis, nausea and vomiting. A maculopapular rash may appear, characterized by a flat, red area covered with small, closely connected bumps. (It may only appear red in pale-skinned people.) Acute symptoms resolve in seven to 10 days.

Rare complications include uveitis or retinitis (eye infections), myocarditis, hepatitis, nephritis, blistered skin lesions, hemorrhage, meningoencephalitis, myelitis (infection of white or gray matter of the brain), Guillain-Barré syndrome and cranial nerve palsies. Persons at risk for severe disease include newborns exposed during delivery; people older than 65; and those with underlying conditions such as hypertension, diabetes or cardiovascular disease. Some individuals may have a relapse of rheumatologic symptoms in the months following an acute illness or may endure joint pain for months to years. Deaths are rare.

Chikungunya virus infection should be considered in patients with acute onset of fever and joint pain, especially travelers recently returning from areas with known transmission. Diagnosis is based on place of residence, travel history and exposures. Blood testing for chikungunya is performed at the Centers for Disease Control, a few state health departments and one commercial laboratory; test results are usually available four to 14 days after the specimen was received. Health care providers are encouraged to report suspected cases to state and local health departments to facilitate diagnosis and alleviate local transmission.

Health departments should perform surveillance for chikungunya cases in returning travelers and be aware of the risk of local transmission in areas where Aedes mosquitoes are active. State health departments should report confirmed infections to the CDC.

It is important to differentiate chikungunya from dengue virus, which is transmitted by the same mosquitoes and has a similar clinical presentation. The two viruses can circulate in the same area and cause occasional co-infections in the same patient. Chikungunya is more likely to cause high fever, severe joint pain, arthritis, rash and lymphopenia (decreased white blood cells). Dengue more likely causes blood abnormalities such as neutropenia, leading to increased susceptibility to infection; and thrombocytopenia, the inability of the blood to clot, causing hemorrhage, shock and death. Patients with suspected chikungunya should be managed as dengue cases until dengue is ruled out.

Most epidemics in Africa occur in tropical rainy seasons and decline during dry seasons; however, outbreaks can occur after periods of drought when household water containers serve as mosquito breeding grounds.

Caribbean countries are on high alert and travelers to the area are cautioned to take preventative measures. Jamaica strengthened its surveillance and mosquito control measures. Many islands warn residents to remove standing water, use repellents and see a doctor at the first symptoms.

There is no medication for the chikungunya virus. Treatment involves assessing hydration and decreasing symptoms. Get plenty of rest, drink fluids to prevent dehydration and take medications such as ibuprofen, naproxen, acetaminophen or paracetamol to relieve fever and pain. Persistent joint pain may require the use of corticosteroids or physiotherapy. Supportive care may include hospitalization, intravenous therapy and the monitoring of hemodynamic status. Evaluate for other serious conditions such as dengue, malaria and bacterial infections and treat and manage appropriately.

As there is no vaccine for the virus, it is important to prevent and control exposure to mosquitoes using the following measures. Use airconditioning or window/door screens in your home. Use mosquito repellents on exposed skin. The most effective repellents for long-lasting protection contain DEET, picaridin, IR3535, oil of lemon eucalyptus and para-menthane-diol products. Cover exposed skin with long-sleeved shirts, long pants and hats. Consider wearing permethrin-treated clothing as a safeguard against bites. Empty standing water from outdoor containers and support local mosquito control programs.

People at increased risk for severe disease should steer clear of traveling to areas with ongoing chikungunya outbreaks. If you are sick with chikungunya, avoid mosquitoes and mosquito bites to prevent further spread of the virus.

Preparing for possible chikungunya outbreaks in the Americas since 2006, the CDC developed a regional surveillance and response program, diagnostic test training and an evaluation program for regional reference laboratories. They also publish traveler health notices for outbreaks in other regions. The spread of this viral infection into the Caribbean illustrates how quickly diseases can multiply with global travel.

The content of this article is for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition.