Chikungunya

Primary reference(s)

WHO, 2020. Chikungunya. World Health Organization (WHO). Accessed 4 November 2020.

Additional scientific description

Chikungunya is a mosquito-borne viral disease first described during an outbreak in southern Tanzania in 1952. It is an RNA virus that belongs to the Alphavirus genus of the family Togaviridae. The name ‘chikungunya’ derives from a word in the Kimakonde language, meaning ‘to become contorted’, and describes the stooped appearance of sufferers with joint pain (arthralgia) (WHO, 2020).

Chikungunya virus is transmitted between humans through the bites of infected mosquitoes – mainly of the Aedes aegypti and A. albopictus species. Both species can also transmit other mosquito-borne viruses, including dengue and Zika fever viruses. The clinical picture of the infection is characterised by abrupt onset of fever frequently accompanied by arthralgia. Other symptoms include muscle pain, headache, nausea, fatigue and a rash usually involving the limbs and trunk (WHO, 2020).

Laboratory diagnosis is via serological and/or virological testing. Serological testing may confirm the presence of antichikungunya antibodies. Immunoglobulin M (IgM) antibody levels are highest three to five weeks after onset of symptoms. Virological testing may isolate the virus itself and should be performed on samples collected during the first week after onset of symptoms (WHO, 2020).

Metrics and numeric limits

Chikungunya has been identified in over 60 countries in Asia, Africa, Europe and the Americas (WHO, 2020).

The European Centre for Disease Prevention and Control (ECDC) has published case classifications for outbreak management, epidemiological surveillance, and reporting (ECDC, 2018).

Examples of drivers, outcomes and risk management

The proximity of mosquito vector breeding sites to human habitation is a significant risk factor for chikungunya as well as for other diseases that Aedes mosquito species transmit. At present, the main method to control or prevent the transmission of chikungunya virus is to combat the mosquito vectors. Prevention and control relies heavily on reducing the number of natural and artificial water-filled container habitats that support breeding of the mosquitoes. This requires mobilisation of affected and at-risk communities, to empty and clean containers that contain water on a weekly basis to inhibit mosquito breeding and the subsequent production of adults. Sustained community efforts to reduce mosquito breeding can be an effective tool to reduce vector populations (WHO, 2020).

During outbreaks, insecticides may be sprayed to kill flying mosquitoes, applied to surfaces in and around containers where the mosquitoes land, and used to treat water in containers to kill the immature larvae. This may also be performed by health authorities as an emergency measure to control the mosquito population (WHO, 2020).

For protection during outbreaks of chikungunya, clothing which minimises skin exposure to the day-biting vectors is advised. Repellents can be applied to exposed skin or to clothing in strict accordance with product label instructions. For those who sleep during the daytime, particularly young children, or sick or older people, insecticide-treated mosquito nets afford good protection, because the mosquitoes that transmit chikungunya feed primarily during the day. Basic precautions should be taken by people travelling to risk areas and these include use of repellents, wearing long sleeves and pants and ensuring rooms are fitted with screens to prevent mosquitoes from entering (WHO, 2020).

There is no specific antiviral drug treatment for chikungunya. The clinical management targets primarily to relieving the symptoms. There is no commercial vaccine available to protect against chikungunya virus infection. While there are several vaccine strategies being pursued (as of mid-2020), of which some are in various stages of clinical trials, they are still several years away from being licensed and available to the public. Prevention of infection by avoiding mosquito bites is the best protection (WHO, 2020).