Pictures of chikungunya and disease information have been excerpted from VisualDx clinical decision support system as a public health service. Additional information, including symptoms, diagnostic pearls, differential diagnosis, best tests, and management pearls, is available in VisualDx.

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Chikungunya is a mosquito-borne alphavirus of the Togaviridae family endemic in sub-Saharan Africa, Southeast Asia, Indonesia, the Philippines and India, with the first local transmission in the Americas being reported in late 2013 on islands in the Caribbean. Many cases have since been reported in the Caribbean, especially the Dominican Republic. The typical clinical presentation is fever and joint pain.

The incubation period of chikungunya is 1-12 days (usually 2-3 days). The initial symptoms consist of the abrupt onset of 3-10 days of flu-like illness with fever, chills, arthralgias, rash, myalgias, severe headache, retro-orbital pain, and photophobia. The fever is high and remitting (a fever that goes up and down without ever returning to normal). Pruritus may be noted. Per the CDC, approximately 3% to 28% of people infected with the virus will remain asymptomatic.

The arthralgias are typically polyarticular and migratory, primarily affecting the small joints of the hands, wrists, ankles and feet, and may last for weeks to months. Flushing of the face and trunk is seen and then macules and papules develop on the trunk and extremities and, occasionally, the palms, soles, and face. Buccal and palatal exanthems may be present. Lymphadenopathy and sore throat may be seen in some patients. Rarely, mucosal and gastrointestinal hemorrhage may occur. Mucosal involvement is more likely in children. Neonates, elderly individuals, and those with underlying medical conditions are at higher risk for severe or atypical disease.

Chikungunya is transmitted by the bite of infected mosquitoes, primarily Aedes aegypti and Aedes albopictus (which can also transmit dengue virus). Natural reservoirs include humans, primates, other mammals, and birds, but humans are the primary amplifying host (ie, can infect mosquitoes that bite them during the first week of illness). Person-to-person transmission of chikungunya has not been documented. An experimental vaccine exists but is not yet available. There is no specific antiviral therapy; treatment is supportive.

Travelers to endemic areas are at higher risk for contracting chikungunya. As of November 4, over 1600 travel-associated cases were reported throughout the United States in 2014, resulting in 11 locally transmitted cases (all in Florida). Travelers to areas with known ongoing outbreaks should use mosquito repellents, long sleeve shirts, long pants, etc, to help prevent bites from these aggressive day-biting mosquitoes.

Chikungunya differential

A patient presenting with chikungunya

A patient presenting with chikungunya

Look For:

Arthralgias, usually bilateral and symmetrical, of the small joints (wrists, ankles, phalanges) and acute fever.

The rash begins as flushing of the face and trunk and then progresses to macules and then erythematous papules on the trunk and extremities. The rash is associated with painful small joint polyarticular arthralgias. Occasionally, the rash may also appear on the face, palms, and soles. The lesions may include petechiae or vesicles.

The rash can be difficult to identify in patients with deeply pigmented skin.

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