Chikungunya is a viral disease (genus Alphavirus) which is transmitted to humans by infected mosquitoes – including Aedes aegypti and Aedes albopictus. The name chikungunya originates from a verb in the Kimakonde language, meaning 'to become contorted'. This refers to the 'stooped' appearance of those suffering with joint pain.
Symptoms appear between 4 and 7 days after the patient has been bitten by the infected mosquito and these include:
- High fever (40°C/ 104°F)
- Joint pain (lower back, ankle, knees, wrists or phalanges)
- Joint swelling
- Muscle pain
Chikungunya is rarely fatal. Symptoms are generally self-limiting and last for 2–3 days. The virus remains in the human system for 5-7 days and mosquitoes feeding on an infected person during this period can also become infected. Chikungunya shares some clinical signs with dengue and can be misdiagnosed in areas where dengue is common.
Chikungunya can be detected using serological tests. Recovery from an infection will confer life-long immunity.
Chikungunya has been identified in nearly 40 countries. Map of countries at risk available here
Countries having documented, endemic, or epidemic chikungunya are:
Asia: Human chikungunya virus infection has been documented in Cambodia, East Timor, India, Indonesia, Laos, Malaysia, Maldives, Myanmar, Pakistan, Philippines, Réunion, Seychelles, Singapore, Taiwan, Thailand and Vietnam.
Africa: Chikungunya occurs in Benin, Burundi, Cameroon, Central African Republic, Comoros, Congo (DRC), Equatorial Guinea, Guinea, Kenya, Madagascar, Malawi, Mauritius, Mayotte, Nigeria, Senegal, South Africa, Sudan, Tanzania, Uganda and Zimbabwe.
Europe and the Americas: Aside from minor incidence rates caused by imported cases from travelers, Italy is the only European country which has had an outbreak. The Americas have not had any major outbreaks so far.
Chikungunya was first identified in Tanzania in the early 1952 and has caused periodic outbreaks in Asia and Africa since the 1960s.
Outbreaks are often separated by periods of more than 10 years. Between 2001 and 2011, a number of countries reported on chikungunya outbreaks.
2005-2006: More than 272 000 people were infected during an outbreak of Chikungunya in the Indian Ocean islands of Réunion and Mauritius where Ae. albopictus was the presumed vector.
2006: Outbreak in India, more than 1 500 000 cases of chikungunya were reported with Ae. aegypti implicated as the vector.
2007: Migration of infected people introduced the infection in a coastal village in Italy. This outbreak (197 cases) confirmed that mosquito-borne outbreaks by Ae. albopictus are plausible in Europe.
Prevention and control
In areas where the vector of chikungunya is Ae. aegypti and Ae. albopictus, vector prevention and control can be combined with dengue control efforts. See “Control strategies”.