Chikungunya fever

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.

Epidemiology¹

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 160 cases reported in the UK in 2025, which is the highest number since 2014 and a 43% increase on 2024. Nearly half were associated with travel to Sri Lanka and almost a quarter were associated with travel to either India or Bangladesh. Most of them occurred between April and September.²

Risk factors ¹³⁴

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.

Presentation¹⁵

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 3-7 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.

• Other symptoms include abdominal pain, headache, diarrhoea, and vomiting, and eye symptoms such as uveitis, conjunctivitis, and retinitis.

• 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.

Investigations

Blood samples should be sent (with clinical and travel history) to the Rare and Imported Pathogens Laboratory (RIPL) in England for diagnosis.⁶ From the perspective of primary care, if a case is suspected then referral to the nearest infectious diseases team would be appropriate and they can contact RIPL if they think that chikungunya is likely. 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.

Differential diagnosis⁷

The picture may be confused with the various viral haemorrhagic fevers or malaria.

• Dengue fever.

• Leptospirosis.

• Malaria.

• Rheumatic fever.

• Other viral illnesses such as influenza.

Management

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.⁸

Complications

Complications which have been described include:³⁷⁹

• 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.

• Hepatitis.

• Acute kidney injury.

Prognosis

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.¹ 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 comorbidities.⁴

Prevention⁴

Two vaccines against chikungunya were approved by the Medicines and Healthcare products Regulatory Agency (MHRA) in 2025; neither are available on the NHS.¹⁰

¹¹

Vaccination should be considered for those travelling to regions with active chikungunya outbreaks, long-term or frequent travellers to regions with known chikungunya transmission in the last five years and laboratory staff who work with chikungunya.

The live vaccine IXCHIQ has been associated with serious adverse events in older patients and those with co-morbidities. In February 2026, the Commission on Human Medicines announced that it should not be used in adults aged ≥60 or in those who are immunosuppressed or have hypertension, cardiovascular disease, chronic kidney disease, or diabetes mellitus. It should be given no later than 30 days before travel and must be preceded by 'a comprehensive benefit risk assessment by a healthcare professional trained in the benefit risk assessment of live vaccines'.¹²

As both vaccines are new to the UK, any adverse effects should be reported via the yellow card system.¹³

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. Travellers to endemic areas should be advised to follow the advice given on Travel Health Pro website - 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.