Chikungunya is a viral disease transmitted to humans by infected mosquitoes. It is caused by the chikungunya virus. While mortality is low, infection with the virus frequently causes chronic and severe joint pain that is often debilitating. There are no vaccines or specific drug against this virus.
This disease mostly occurs in Africa, Asia and the Indian subcontinent but it is fast spreading with outbreaks outside of its original territory becoming more frequent. Due to tests not being commonly available, the is no real estimate for the number of people affected by the disease globally on an annual basis.
New infections per year
Dead per year
What causes Chikungunya
Chikungunya is a viral disease carried by infected Aedes (A. aegypti and A. albopictus) mosquitos which also transmit the Dengue and Zika virus. These mosquitos can be identified by the white markings on its legs, and bite during the day and night. They’re rarely transmitted from mother to child or via infected blood.
The Chikungunya virus belongs to the genus alphavirus in the family Togaviridae and was first isolated in 1953 during an epidemic among the Makonde tribe in Tanzania. It is a member of the Semliki Forest virus complex and is closely related to Ross River virus, O’nyong’nyong virus, and Semliki Forest virus. It can also be referred to as an arbovirus (arthropod-borne virus).
Where is Chikungunya found
As of 2020, chikungunya cases have been reported in all continents except Australia and Antarctica, although in theory, outbreaks can occur anywhere where the Aedes mosquitos can thrive. Chikungunya could have emerged as early as the 18th century; however, the largest outbreak ever recorded was in Reunion in western Indian Ocean in 2005 – 2006.
In the latter half of the 2000s and the 2010s, other major outbreaks have been reported in India, Italy, Thailand, Cambodia, the Caribbean, United States, Venezuela, Costa Rica, Cambodia, France, Brazil, El Salvador, Mexico, Colombia and the Republic of Congo, with the latest cases being in the last two.
What are the symptoms of Chikungunya
Chikungunya is typically characterized by muscle and often debilitating joint pain. In fact the name translates to ‘that which bends up’, referring to people’s postures due to joint pain. Onset of illness usually occurs 4-8 days after being bitten by an infected mosquito.
Other symptoms include headache, muscle pain, joint swelling and rashes. It is usually not a life-threatening illness, but symptoms can be severe and disabling. While most patients feel better within a week, joint pain can last for months or even years when it develops into a chronic disease.
As with several other viral diseases, newborns, older adults above 65 and those with pre-existing medical conditions such as a high blood pressure, diabetes or heart disease are more likely to have a severe infection. Co-infection with Dengue or other mosquito-borne viruses may also cause more severe disease.
How can Chikungunya be prevented
Currently, there is no vaccine for the prevention of Chikungunya.
Controlling mosquito populations is the main way to prevent and reduce Chikungunya. This includes source reduction, pesticide spraying for larval control and fumigation for adult control, and/or the use of mosquito traps.
Wear long-sleeved clothing and long trousers when outdoors.
Use mosquito netting over the bed if the bedroom is not air conditioned or screened, and for additional protection, treat the mosquito netting with the insecticide permethrin.
How is Chikungunya diagnosed
Due to its resemblance to other viral and mosquito-borne diseases that cause fever, clinical diagnosis is often difficult. Clinically, acute onset of high fever and severe joint pain would lead to suspicion of Chikungunya.
The infection can be confirmed in the acute phase by using Polymerase chain reaction (PCR) tests, such as the ones made available by the WoIDM. Latent cases, up to a couple of months after the onset of symptoms, are better diagnosed by an ELISA test which detects antibodies to the virus, but these tests may produce false positives.
How is Chikungunya treated
Currently, no specific treatment for Chikungunya is available. Supportive care is recommended, based on symptoms.
The use of corticosteroids is not recommended, as they may cause immunosuppression and worsen infection. It is also best to avoid medication that can can cause bleeding, such as aspirin, until Dengue has been ruled out.
Ribavirin, an antiviral drug, can be used as treatment but with weak evidence. Treatment is most effective when it is started early in the course of the disease.
Methotrexate, a drug used in the treatment of rheumatoid arthritis, has shown to have benefit in treating inflammatory poly-arthritis in Chikungunya.
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