Chikungunya's name comes from a Makonde word meaning to become contorted
First identified in Tanzania in 1952, chikungunya takes its name from the bent posture of people wracked by its joint pain. Spread by the same daytime-biting mosquitoes that carry dengue and Zika, it has surged across the tropics and into some temperate regions since the 2000s.
The illness usually starts suddenly, three to seven days after an infected bite, with a fever above 39 °C and severe pain in many joints at once, often mirrored on both sides of the body. Wrists, ankles, hands and feet are common targets, along with shoulders, elbows and knees. About half of patients develop a rash, which in some cases covers more than 90 percent of the skin. Yet between 17 and 40 percent of infections cause no symptoms at all.
For most people the acute phase fades within about a week. Among those with severe illness, however, roughly 30 to 40 percent keep having symptoms, mainly arthritis and inflamed tendons, for months or even years. The reason is persistence: antibodies clear the virus from the blood after about a week, but it can hide inside joint tissue and keep inflammation going. The virus also dodges immunity actively, with a protein called nsP2 blocking antiviral signalling inside infected cells.
Two mosquitoes do the spreading. Aedes aegypti thrives in tropical cities but struggles with cold, while the Asian tiger mosquito, Aedes albopictus, tolerates a wider range of temperatures and can overwinter as eggs in temperate zones, helping the disease move north. A mosquito picks up the virus from a person's blood during the first days of illness, when viral levels are high, and passes it on with a later bite.
Diagnosis relies on blood tests for viral genetic material in the first week or antibodies afterwards, and it is easily confused with dengue or malaria. No specific antiviral treatment exists, though vaccines have been approved in the United States and the European Union. Deaths are uncommon, slightly under one in a thousand symptomatic cases, mostly in newborns, older adults and people with chronic illness. A multi-country analysis covering 2008 to 2024 found that El Niño conditions raised chikungunya risk after a lag of two years, while La Niña suppressed it.
Source: Chikungunya
