Chikungunya is one of a group of arboviruses (of the family Togaviridae) and is transmitted by mosquitoes (usually of the Aedes spp.). They tend to bite during daylight.
Its name derives from a verb from the Kimakonde language, meaning "to become contorted", referring to the affected person's stooped posture caused by joint pains. It was first described in southern Tanzania in 1952.
The geographical distribution of chikungunya fever has changed in recent years. Initially found in Africa, there were at first few cases reported. In 2005, this strain underwent mutation and spread across the islands of the Indian Ocean. By 2006-2007, the outbreak had reached India and other parts of Asia and Southeast Asia, as well as parts of the Pacific region.
In 2013, there was first notification of locally acquired chikungunya fever in the Caribbean and since that time there have been a huge number of cases in the Caribbean and the Americas. More than 1.2 million cases have been reported in 44 countries or territories in the Americas since.
There have been no locally acquired cases in the UK, as the temperature is not warm enough for this mosquito to breed; however, cases acquired in travellers have increased since the spread of the virus to the Caribbean and Americas. In 2014, there were 295 reported cases in England, Wales and Northern Ireland, with 88% having been acquired in the Caribbean or South America. Prior to this geographical spread, there were few cases and these had mostly been acquired in India or Southeast Asia.
There were a few locally acquired cases in the South of France in 2014.
Regions affected are those with warm tropical or subtropical climates. Risk is highest in the rainy season when numbers of mosquitoes are at their greatest. The infection is not transmitted directly between humans but only through the bite of a mosquito which has bitten another infected individual. Vertical transmission from mother to child has been reported, and neonates have been reported to contract the disease from infected mothers, with severe consequences.
It affects all age groups but more than 50% of those with severe disease are over the age of 65 years - of which a third will die. Usually those with the severe form of the disease and complications have underlying morbidity. Severe illness also occurs in children.
The illness characteristically begins with rapid onset of fever and joint pains. It may or may not be accompanied by the following: muscle pain, headache, nausea, fatigue and a rash.
- Incubation period is 4-8 days.
- There is sudden onset of fever and, with it, a severe, crippling migrating, polyarticular arthritis. This most often affects ankles, wrists and hands but can affect any joint. Joint pain is usually the most disabling and the longest-lasting symptom.
- If a rash develops, it is usually between the second and fifth day of illness. It is macular or maculopapular in nature, mostly on the trunk and limbs.
- Rarely, complications develop which are described in the 'Complications' section below; however, this is more common in young children or elderly people with other morbidity.
- Most patients recover within a few days and death is a rarity. Arthritis may persist for rather longer in some, even several months or years.
Blood samples should be sent (with clinical and travel history) to the Rare and Imported Pathogens Laboratory (RIPL) in England for diagnosis. If a case is suspected, phone the RIPL for advice on 01980 612348.Diagnosis depends on the detection of virus or antibodies within the blood sample.
Extreme care should be taken when obtaining blood samples and handling specimens.
The picture may be confused with the various viral haemorrhagic fevers or malaria.
The management largely revolves around symptom relief and supportive care. There is no antiviral treatment for chikungunya.
Fever is marked and, especially in a hot environment, plenty of fluid should be drunk. Paracetamol and ibuprofen may help to relieve pyrexia and pain.
Potential future antiviral therapeutic options for chikungunya are being researched.
- Development of a chronic stage characterised by polyarthralgia that can last from weeks to years.
- Respiratory failure.
- Neurological manifestations including seizures, meningoencephalitis, altered level of consciousness.
- Severe sight impairment due to retrobulbar neuritis has been reported. Other ocular complications include anterior uveitis, optic neuritis, and dendritic lesions.
- Cardiovascular decompensation.
- Acute kidney injury.
There may be an association with the chikungunya virus and Burkitt's lymphoma. Epstein-Barr virus and malaria have been documented to have a role in the pathogenesis of endemic Burkitt's lymphoma but in some clusters of the disease in Africa infection with chikungunya has also been found to have an association. There are geographical differences in the strength of this association, so other factors are clearly involved.
The majority of patients will recover completely within one to two weeks but some may be left with chronic joint pains which may last several years. Chikungunya virus does not cause death directly but in the presence of other comorbidities it may contribute to a fatal outcome. Death is thought to occur in less than 1 in 1,000 cases and is more likely in young babies, the elderly and those with comorbidity. Over half of those with severe forms of the disease are aged over 65 years and most have other comorbidities. Children are also at risk of more severe disease and may have different manifestations.
There is no vaccine available. Some epidemics have been associated with poor control of mosquitoes. Prevention requires personal protective measures such as the use of insect repellents and public health measures such as mosquito spraying and elimination of breeding places for mosquitoes - eg, stagnant water.
UK travellers visiting areas of current outbreaks are at risk of chikungunya. For UK travellers, information on current outbreaks can be obtained from visiting the professional travel health website, Travel Health Pro, or the public Fit for Travel website.[11, 12] Travellers to endemic areas should be advised to follow the advice given on these websites - if an area is particularly high-risk it may advise that those at higher risk avoid travel. For all, mosquito bite prevention should be advised, ie the use of mosquito repellents, protective clothing (long sleeves and full length trousers) and mosquito nets and screens. Those travelling to high-risk areas should be advised to seek medical advice if they develop a fever and joint pains whilst away or shortly after return.
Further reading and references
; World Health Organization
; Reemergence of chikungunya virus. J Virol. 2014 Oct88(20):11644-7. doi: 10.1128/JVI.01432-14. Epub 2014 Jul 30.
; The efficacy of repellents against Aedes, Anopheles, Culex and Ixodes spp. - a literature review. Travel Med Infect Dis. 2013 Nov-Dec11(6):374-411. doi: 10.1016/j.tmaid.2013.10.005. Epub 2013 Oct 25.
; Public Health England
; Centers for Disease Control and Prevention.
; Chikungunya: a potentially emerging epidemic? PLoS Negl Trop Dis. 2010 Apr 274(4):e623.
; Public Health England
; World Health Organization South East-Asia Regional Office, 2008
; Antiviral perspectives for chikungunya virus. Biomed Res Int. 20142014:631642. doi: 10.1155/2014/631642. Epub 2014 May 15.
; Chikungunya infection in children. Indian J Pediatr. 2009 Feb76(2):185-9. Epub 2009 Mar 28.
; A Role for RNA Viruses in the Pathogenesis of Burkitt's Lymphoma: The Need for Reappraisal. Adv Hematol. 20122012:494758. doi: 10.1155/2012/494758. Epub 2011 Nov 29.
; Travel Health Pro.
; Failure to control mosquitoes has led to two fever epidemics in India. BMJ. 2006 Oct 14333(7572):773.
; Travel Health Pro
; Fitfortravel, Health Protection Scotland
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