Information about Chikungunya

What is chikungunya?
Chikungunya is a mosquito-borne infection that causes an illness that characteristically begins with a rapid onset of fever and joint pains, which may or may not be accompanied by muscle pain, conjunctivitis, and a rash. The chikungunya virus is an alphavirus in the Togaviridae family. It was first isolated from patients during an epidemic in Tanzania in 1952. The name chikungunya comes from a word in the Makonde language (one of the native languages in Tanzania) that means 'that which bends up' owing to the crippling pain in the joints caused by the virus.

Where does chikungunya occur?
Chikungunya occurs in Africa (more specifically West Africa from Senegal to Cameroon, Central and East Africa including Central African Republic, Angola, Democratic Republic of Congo, Zambia, Zimbabwe, Tanzania, Malawi, Mozambique, eastern Botswana, and north eastern parts of South Africa; there is also evidence of viral presence in parts of Ethiopia and Sudan), and Asia (India, Sri Lanka, Thailand, Myanmar, Malaysia, Indonesia, and Cambodia). Outbreaks have also been reported in Saudi Arabia, Papua New Guinea, and more recently in 2006, on islands in the Indian Ocean, including Réunion, Mayotte, Mauritius, and the Seychelles (see HPR: http://www.hpa.org.uk/cdr/archives/2006/cdr0606.pdf). In 2007, a localised outbreak of chikungunya was reported in the north east region of Italy; this outbreak occurred as a result of an imported case from India (see HPR: http://www.hpa.org.uk/hpr/archives/2007/hpr3607.pdf). Chikungunya does not occur in the United Kingdom (UK) because the mosquito vector is not present, but cases are occasionally reported in the UK in people who have travelled to endemic areas. In 2010, 79 cases were reported in England, Wales and Northern Ireland, most of whom acquired their infections in the Indian sub-continent and South East Asia (see epidemiological data pages).

What are the symptoms?
Chikungunya is characterised by a sudden onset of fever usually accompanied by joint pain (arthralgia). However symptoms can range from mild or non-existent to severe. It can often be misdiagnosed as other viral illnesses such as dengue fever in areas where these infections also occur. Other common symptoms of chikungunya include: muscle pain, headache, nausea, fatigue and rash. The joint pain may be very debilitating, but usually ends within a few days or weeks. Most patients make a full recovery, but in some cases joint pain and arthritis may persist for several months, or even years. Occasional cases of eye, neurological and heart complications have been reported, as well as gastrointestinal complaints. Serious complications are not common, but in older people, the disease can contribute to the cause of death.

How do you catch chikungunya?
The chikungunya virus is transmitted by the bite of an infected female Aedes mosquito. Aedes aegypti is most commonly associated with the transmission of chikungunya in tropical and sub-tropical regions but Aedes albopictus (Asian tiger mosquito) has been associated with chikungunya transmission in more temperate regions, e.g. in Italy. When the mosquito feeds on the blood of a person infected with chikungunya, the virus enters and multiplies within the mosquito. After about 8-10 days, the mosquito can transmit the virus to another human and can do this for the rest of its life. Chikungunya is not spread directly from person to person.

How long can you have the infection before developing symptoms?
After being bitten by an infected mosquito, it may take typically between four and eight days for the first symptoms (usually fever and joint pain) to develop, but it can be shorter or longer in some people.

How can you avoid getting chikungunya?
There is no vaccine or drug to prevent chikungunya. The only way to prevent chikungunya is to avoid mosquito bites. Aedes mosquitoes bite during the day particularly around dawn and dusk (as opposed to mosquitoes that transmit malaria, which bite at night between dusk and dawn). A good repellent containing N, N-diethylmetatoluamide (DEET) must be used on exposed skin together with light cover-up clothing. If sunscreen is also being used, repellent must be applied after sunscreen. More information about insect bite avoidance is available from the NaTHNaC website. In endemic areas, control programs rely on the elimination of mosquito breeding sites in the community by regular inspections and insecticide spraying of properties (particularly during an outbreak) and the education of local residents to regularly empty standing water and keep outside areas free from waste items in which water may collect.

How is chikungunya treated?
There is no specific antiviral treatment for chikungunya.  Supportive nursing care and relief of symptoms are the standard treatment.

Is chikungunya catching?
If you acquire chikungunya abroad and become ill on your return to the UK, you cannot pass the infection onto anyone else. The Aedes mosquito needed to transmit the chikungunya virus is not present in the UK because the temperature is not consistently high enough for it to breed. Chikungunya cannot be passed directly from person to person.