Open Outbreak

Chikungunya

Also known as: CHIKV, chikungunya virus disease

Chikungunya is a viral disease spread mainly by Aedes mosquitoes, especially Aedes aegypti and Aedes albopictus. It usually causes sudden fever and severe joint pain. Many people recover from the fever within days, but the joint pain can last for months and sometimes longer. WHO says deaths can occur, but they are typically rare and are reported more often in older adults and people with severe disease or other health problems. In 2025, WHO reported 445271 suspected and confirmed cases and 155 deaths globally between 2025-01-01 and 2025-09-30, showing that the disease can still cause large outbreaks. Chikungunya is now reported across much of the tropical and subtropical world, and it can appear in new places when infected travelers arrive where Aedes mosquitoes are established. There is now a licensed vaccine in some countries, but it is not a full public-health solution on its own. Treatment is mainly supportive, such as fluids, rest, and pain relief, because no specific antiviral treatment is established in the sources used here.

Key facts

TransmissionPrimarily through the bites of infected Aedes mosquitoes, especially Aedes aegypti and Aedes albopictus. Local spread can start when an infected traveler arrives in an area with these mosquitoes and a susceptible population.
Incubationunknown
Case fatalityOverall fatality is described by WHO as low. In the WHO global situation report for 2025, 155 deaths were reported among 445271 suspected and confirmed cases between 2025-01-01 and 2025-09-30 (about 0.03%), but this is an outbreak-period figure, not a universal case fatality rate.
Reproduction numberunknown
VaccineA chikungunya vaccine is licensed in some countries. A 2024 review describes IXCHIQ (VLA1553) as the first licensed chikungunya vaccine.
TreatmentNo specific cure is described in the WHO outbreak notices used here; treatment is focused on relieving symptoms and providing supportive care.
Reservoirunknown
Endemic regionsWidely distributed in tropical and subtropical regions. WHO reported current or previous autochthonous transmission in 119 countries and territories as of 2024.

Transmission

Chikungunya spreads mainly through the bite of infected Aedes mosquitoes. WHO says the main vectors are Aedes aegypti and Aedes albopictus. These mosquitoes often live close to people, especially in towns and cities, and breed in standing water around homes. A person infected while traveling can carry the virus into a new area. If local Aedes mosquitoes are present, onward transmission can begin. WHO warned in 2025 that spread is helped by limited immunity in newly affected areas, favorable breeding conditions, increased human movement, and gaps in surveillance and diagnosis. The disease is therefore not just a tropical travel issue. It can appear in new places when mosquitoes are established and conditions are suitable. The sources used here describe mosquito-borne spread clearly, but they do not give a firm reproduction number, so that remains uncertain on this page.

Symptoms and severity

WHO describes chikungunya as an illness with abrupt fever and joint pain, often with joint inflammation. The joint pain can be very disabling. Other common symptoms include headache, muscle pain, tiredness, nausea, and rash. The fever usually settles, but the pain can continue for months or even years in some people. Severe disease is less common, but it does happen. WHO notes that fatalities are typically rare, yet they are reported, especially in older adults and in people with severe disease or other health problems. The 2025 WHO global report counted 155 deaths among 445271 suspected and confirmed cases reported from 40 countries between 2025-01-01 and 2025-09-30, which shows that death is uncommon but possible. Infants, older people, and people with underlying illness appear to face higher risk of serious outcomes.

Treatment and vaccines

The WHO outbreak notices used here say there is no cure for chikungunya and that care is focused on relieving symptoms. In plain terms, that means supportive treatment rather than a virus-killing medicine proven for routine use. This usually includes rest, fluids, and medicines for pain and fever, guided by a clinician. That matters because the main burden of chikungunya is often not death but painful, sometimes prolonged illness. On vaccines, the picture has changed recently. A 2024 review reports that IXCHIQ, also called VLA1553, became the first licensed chikungunya vaccine in the United States, Europe, and Canada. Another 2024 review describes it as the first approved live-attenuated vaccine against chikungunya. Even so, vaccination does not replace mosquito control, surveillance, and clinical care. The sources used here do not support a claim that vaccine access is widespread globally, so supply and eligibility still matter.

Where it occurs

Chikungunya is now far more widespread than many people realize. WHO said in its 2025 global situation report that current or previous local transmission had been reported from 119 countries and territories across six WHO regions as of 2024. The disease is widely distributed in tropical and subtropical regions, but it is not limited to them forever. WHO also noted 27 countries and territories with established Aedes aegypti mosquitoes that had not yet reported local chikungunya transmission, meaning there are places where the ingredients for spread already exist. Recent WHO notices show activity in the Americas, Africa, Indian Ocean islands, and Europe-linked territories, with outbreaks or locally transmitted cases in places such as La Réunion, Mayotte, Kenya, Chad, Congo, Sudan, Italy, and France. The pattern is best understood as a mosquito-borne disease with a broad global footprint and repeated potential to expand into new receptive areas.

Recent history

This site’s archive count says chikungunya has appeared in 18 archived WHO notices or major pandemic records since 1996, which fits a disease that reappears in waves rather than disappearing. The archive includes major milestones such as La Réunion in 2006, spread in India in 2006, the start of local transmission in Saint Martin in 2013, expansion in the Americas, and later notices from France, Italy, Kenya, Sudan, Congo, and Chad. WHO’s most recent global assessment, published on 2025-10-03, reported a resurgence in 2025 with 445271 suspected and confirmed cases and 155 deaths from 40 countries up to 2025-09-30. WHO highlighted uneven regional trends rather than a single uniform global rise. A separate WHO notice from 2025-05-12 described widespread transmission in La Réunion and increasing local transmission in Mayotte, the first such Mayotte cases since 2005 to 2006. In short, recent history shows repeated expansion, pauses, and renewed outbreaks.

What to watch

Several signals would make chikungunya more concerning. One is spread into new regions that already have Aedes mosquitoes but little population immunity. WHO specifically warns that infected travelers can introduce the virus and start local transmission where competent vectors are present. Another warning sign is sustained local spread in places that have not seen chikungunya for many years, as in the 2025 La Réunion and Mayotte notice. A third is pressure on weak surveillance or diagnostic systems, because outbreaks may then be detected late and appear larger once recognized. A fourth is any change that makes transmission easier, such as wider mosquito distribution linked to climate, transport, urban growth, poor water management, or CHIKV lineages with better transmission in Aedes albopictus. Finally, vaccine availability should be watched. A licensed vaccine now exists, but the sources used here do not show broad global coverage, so supply, access, and targeting could become important if outbreaks widen.

Related outbreaks

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