Chikungunya is a mosquito-borne viral disease. Chikungunya 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). Currently, Chikungunya has been identified in over 60 countries in Asia, Africa, Europe and the Americas.
The virus is transmitted from human to human by the bites of infected female mosquitoes. Most commonly, the mosquitoes involved are Aedes aegypti and Ae. albopictus, two species which can also transmit other mosquito-borne viruses, including dengue. In Africa several other mosquito vectors have been implicated in disease transmission, including species of the Ae. furcifer-taylori group and Ae. luteocephalus. These mosquitoes can be found biting throughout daylight hours, though there may be peaks of activity in the early morning and late afternoon. Both species are found biting outdoors, but Ae. aegypti will also readily feed indoors. After the bite of an infected mosquito, onset of illness occurs usually between 4 and 8 days but can range from 2 to 12 days.
Often symptoms in infected individuals are mild and the infection may go unrecognized, or be misdiagnosed in areas where dengue occurs. However, Chikungunya is characterized by an abrupt onset of fever frequently accompanied by joint pain. Other signs and symptoms include muscle pain, headache, nausea, fatigue and rash. The joint pain is often very debilitating, but usually lasts for a few days or may be prolonged to weeks. Hence the virus can cause acute, subacute or chronic disease. Most patients recover fully, but in some cases joint pain may persist for several months, or even longer. Serious complications are uncommon. Diagnosis can be made by performing serological tests, such as enzyme-linked immunosorbent assays (ELISA) to confirm the presence of IgM and IgG anti-chikungunya antibodies, or by viral isolation from the blood during the first few days of infection using reverse transcriptase-polymerase chain reaction (RT-PCR).
There is no specific antiviral drug treatment for chikungunya. Treatment is directed primarily at relieving the symptoms, including the joint pain using anti-pyretics, optimal analgesics and fluids. There is no commercial chikungunya vaccine. At present, the main method to control or prevent the transmission of Chikungunya virus is to combat vector mosquitoes through:
- Preventing mosquitoes from accessing egg-laying habitats by environmental management and modification;
- Disposing of solid waste properly and removing artificial man-made habitats;
- Covering, emptying and cleaning of domestic water storage containers on a weekly basis;
- Applying appropriate insecticides to water storage outdoor containers;
- Using of personal household protection measures, such as window screens, long-sleeved clothes, repellents, insecticide treated materials, coils and vaporizers;
- Improving community participation and mobilization for sustained vector control
References:
Powers AM, Logue CH. Changing patterns of chikungunya virus: re-emergence of a zoonotic arbovirus. J Gen Virol. 2007;88(Pt 9):2363-77.
Thiberville SD, Moyen N, Dupuis-Maguiraga L, Nougairede A, Gould EA, Roques P, et al. Chikungunya fever: epidemiology, clinical syndrome, pathogenesis and therapy. Antivir Res. 2013;99(3):345-70.
World Health Organization. Chikungunya [updated 12 April 2017]. Available from: https://www.who.int/news-room/fact-sheets/detail/chikungunya.
