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, India, and now, the Americas. The first local transmission in the Americas was reported in late 2013 on islands in the Caribbean. Many cases have since been reported in the Caribbean, especially the Dominican Republic, and throughout Central and parts of South America. The typical clinical presentation is fever and joint pain with many, but not all, patients developing a rash.

The incubation period of chikungunya is 1-14 days (usually 3-7 days). The initial symptoms consist of the abrupt onset of 3-7 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). Arthralgias often precede the onset of fever in nearly three-fourths of cases. Pruritus may be noted. The rash of chikungunya may consist of widespread erythematous macules or macules and papules. The severity of disease varies across a wide spectrum. Per the CDC, approximately 3%-28% of people infected with the virus will remain asymptomatic. In a 2016 report of 110 nonpregnant adults hospitalized due to chikungunya virus infection in Guadeloupe, 42 had a severe form of disease with a syndrome consistent with severe sepsis or septic shock. Severe illness and death have also been reported in a subset of patients during other outbreaks, including on Reunion Island.

Arthralgias are typically symmetrical, involve many joints, and are migratory. They primarily affect 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. Hypocalcemia and an elevated creatine kinase level may occur 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 (high blood pressure, diabetes, and heart disease) 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, humans can infect mosquitoes that bite them during the first week of illness). Person-to-person transmission of chikungunya has not been documented, although there have been reports of maternal-fetal transmission in the perinatal period in mothers with acute infection, with subsequent high levels of morbidity for the neonate. There is no evidence supporting transmission via breastfeeding. 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. In 2014, over 1600 travel-associated cases were reported throughout the United States, resulting in 11 locally transmitted cases (all in Florida). Travelers to areas with known ongoing outbreaks should use mosquito repellents, long-sleeved 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:

Skin findings are present in around 40%-75% of cases. The rash typically begins as flushing of the face and trunk and then progresses to macules and then erythematous papules on the trunk and extremities. Chikungunya is associated with painful small joint polyarticular arthralgias. Occasionally, the rash may also appear on the face, palms, and soles. It may be difficult to identify in patients with deeply pigmented skin.

Oral manifestations are a less frequent occurrence and are seen more commonly in children. Perineal, genital, and intertriginous ulceration has also been reported.

Variant presentations include the presence of petechiae, purpura, targetoid lesions, vasculitic lesions, or vesicles and bullae. The vesiculobullous form is more commonly seen in children.

Prominent hyperpigmentation has been reported to occur in the second week of the disease and may follow resolution of rash or may develop without obvious preceding rash. Hyperpigmentation may be diffuse or localized to the face, arms, and limbs. Centrofacial pigmentation is characteristic. Freckle– or melasma-like presentations have been reported. Reported nail changes include black lunulae and diffuse, transverse, and longitudinal melanonychia.

Exacerbation of preexisting dermatoses, such as psoriasis, has also been reported.

Impact of skin color on clinical presentation: In darker skin colors, erythema may be subtle and difficult to appreciate. A violaceous hue may be seen. A bright light may highlight any subtle color changes present. Look also for textural changes. In lighter skin colors, the redness is more apparent.

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