Chikungunya is an infection caused by the chikungunya virus. The most common symptoms are fever and joint pain, typically occurring four to eight days after the bite of an infected mosquito; however some people may be infected without showing any symptoms. Other symptoms may include headache, muscle pain, joint swelling, and a rash. Symptoms usually improve within a week; however, occasionally the joint pain may last for months or years. The very young, old, and those with other health problems are at risk of more severe disease.
The virus is spread between people by two species of mosquito in the genus Aedes: Aedes albopictus and Aedes aegypti, which mainly bite during the day, particularly around dawn and in the late afternoon. The virus may circulate within a number of animals, including birds and rodents. Diagnosis is done by testing the blood for either viral RNA or antibodies to the virus. The symptoms can be mistaken for those of dengue fever and Zika fever, which are spread by the same mosquitoes. It is believed most people become immune after a single infection.