Definition and epidemiology
Chikungunya is an acute febrile illness caused by chikungunya virus (CHIKV), a single-stranded RNA alphavirus in the family Togaviridae. It is transmitted to humans through the bite of infected Aedes aegypti or Aedes albopictus mosquitoes, the same vectors responsible for dengue and Zika.
The disease is endemic in parts of Africa, Asia, and the Indian subcontinent, with large epidemics also reported in the Americas and Europe since 2004-2005. Outbreaks tend to follow rainy seasons when mosquito breeding increases. Attack rates during outbreaks can be very high (often 30-50% of exposed populations), and all age groups are susceptible, though neonates, older adults, and those with comorbidities are at higher risk for severe disease.
The name "chikungunya" derives from a Makonde (Tanzanian) word meaning "that which bends up," referring to the stooped posture caused by severe joint pain.
- CHIKV is an alphavirus transmitted by Aedes aegypti/albopictus, same vectors as dengue
- Hallmark feature is severe, often symmetric, polyarthralgia/arthritis of small joints
- Rash occurs in about half of patients, usually maculopapular
- Avoid aspirin/NSAIDs until dengue is excluded due to bleeding risk
- RT-PCR is best in the first week; IgM serology becomes useful after day 5
- No specific antiviral exists; treatment is supportive
- Chronic arthritis can persist for months to years after acute infection in many patients
- A live-attenuated vaccine (IXCHIQ) is now available for at-risk adults in some countries
Etiology and risk factors
- Causative agent: Chikungunya virus (CHIKV), genus Alphavirus
- Vectors: Aedes aegypti (also the main dengue vector) and Aedes albopictus, both day-biting mosquitoes
- Transmission: Human-mosquito-human cycle; humans are the primary amplifying host during outbreaks
- Risk factors for exposure: Residence in or travel to endemic/epidemic areas, outdoor activity during daytime, standing water near dwellings (breeding sites)
- Risk factors for severe/atypical disease: Age under 1 year or over 65 years, pregnancy (risk of vertical transmission around delivery), underlying cardiovascular, renal, or hepatic disease
Vertical transmission can occur intrapartum if the mother is viremic at delivery, which can cause severe neonatal disease. Mosquito-borne transmission (not person-to-person via casual contact) is the overwhelmingly dominant route.
Pathophysiology
After inoculation by mosquito bite, CHIKV replicates locally in fibroblasts, macrophages, and endothelial cells, then disseminates via viremia to joints, muscles, liver, and the central nervous system.
The virus has a particular tropism for joint and musculoskeletal connective tissue (synovial fibroblasts, skeletal muscle satellite cells), which explains the prominent and often prolonged arthralgia/arthritis. Infection triggers a strong innate immune response with type I interferon release, followed by infiltration of monocytes/macrophages and production of pro-inflammatory cytokines (IL-6, IL-1β, TNF-α) in synovial tissue.
Persistence of viral antigen or RNA in joint tissue, along with ongoing immune activation, is thought to underlie the chronic inflammatory arthritis seen in some patients months after the acute infection resolves. Unlike dengue, chikungunya rarely causes plasma leakage or hemorrhagic shock, though hemorrhagic manifestations can occur in rare, severe cases.
Clinical features
Acute phase (first 1-2 weeks)
- Sudden-onset high fever (often 39°C/102°F or higher), typically lasting 3-7 days
- Severe, symmetric polyarthralgia/arthritis, classically affecting small joints of hands, wrists, ankles, and feet, but can involve large joints too
- Maculopapular rash (trunk and limbs) in roughly half of patients, appearing a few days after fever onset
- Myalgia, headache, and conjunctival injection
- Peripheral edema around affected joints
Subacute/chronic phase
- Persistent or relapsing joint pain and stiffness lasting weeks to months (and in some patients, years) after the acute illness
- Can resemble an inflammatory arthropathy similar to rheumatoid arthritis in a subset of patients
Severe/atypical presentations (uncommon)
- Neurologic: encephalitis, Guillain-Barré syndrome
- Myocarditis
- Hepatic dysfunction
- Severe disease is more common in neonates, the elderly, and those with comorbidities
Diagnosis
Diagnosis is based on clinical presentation plus epidemiologic exposure (travel to or residence in an endemic/outbreak area) confirmed by laboratory testing.
Laboratory confirmation
| Timing after symptom onset | Preferred test |
|---|---|
| Day 0-7 | RT-PCR for CHIKV RNA (highly sensitive early) |
| Day 5 onward | IgM serology (ELISA) |
| Convalescent | IgG serology, often with paired acute/convalescent titers |
- Viral culture is possible but not used routinely for clinical diagnosis
- Cross-reactivity with other alphaviruses can occur on serology, so confirmatory neutralization testing may be needed in ambiguous cases
Supportive labs
- Often mild leukopenia and lymphopenia
- Mild thrombocytopenia (less pronounced than in dengue)
- Elevated inflammatory markers (CRP) and sometimes mildly elevated transaminases
Because clinical overlap with dengue and Zika is substantial and co-circulation is common, testing for all three (or at least ruling out dengue) is important before starting NSAIDs.
Differential diagnosis
- Dengue fever: Also mosquito-borne (Aedes), but more associated with retro-orbital pain, thrombocytopenia with bleeding risk, and warning signs for severe plasma leakage; arthralgia less prominent and less persistent than in chikungunya
- Zika virus infection: Milder fever, prominent conjunctivitis and rash, concern for congenital microcephaly; arthralgia typically less severe
- Rheumatoid arthritis / other inflammatory arthropathies: Consider when joint symptoms persist for months; lacks the acute febrile mosquito-exposure history
- Parvovirus B19 infection: Symmetric small-joint arthritis, especially in adult women, with "slapped cheek" rash in children
- Malaria: Fever with travel history, but typically cyclical fevers without the prominent polyarthralgia
- Leptospirosis and other arboviral/rickettsial infections: Overlapping febrile illness in tropical travelers
Management
There is no specific antiviral treatment approved for chikungunya; management is supportive, consistent with CDC and WHO guidance.
Acute phase
- Rest, oral hydration
- Acetaminophen (paracetamol) for fever and pain, first choice
- NSAIDs (e.g., ibuprofen, naproxen) can be used for pain and inflammation once dengue has been excluded, since NSAIDs and aspirin increase bleeding risk if dengue is present
- Avoid aspirin during the acute febrile phase for the same reason
- Mosquito avoidance (bed nets, repellents) during the viremic period to limit further transmission
Persistent/chronic arthritis
- NSAIDs remain the mainstay
- Short courses of corticosteroids or disease-modifying antirheumatic drugs (e.g., methotrexate, hydroxychloroquine) have been used in refractory, rheumatoid-arthritis-like chronic chikungunya arthritis, under specialist (rheumatology) guidance
- Physical therapy to maintain joint mobility
Prevention
- A live-attenuated chikungunya vaccine (IXCHIQ) has been approved in the US and some other countries for adults, particularly travelers to endemic areas and those at risk during outbreaks; recommendations continue to evolve and vary by country
- Primary prevention remains vector control (eliminating standing water, insecticide use) and personal protection (repellents, protective clothing)
- Hospitalization is rarely required except for severe disease, dehydration, or complications in high-risk patients (neonates, elderly, significant comorbidities)
Complications and prognosis
Most patients recover from the acute febrile illness within 1-2 weeks, but a substantial proportion (estimates commonly cited around 30-40%, varying by study) develop persistent or relapsing arthralgia/arthritis lasting months to years, sometimes called chronic chikungunya arthritis.
Complications
- Chronic inflammatory polyarthritis, occasionally indistinguishable from rheumatoid arthritis
- Rare neurologic complications: encephalitis, Guillain-Barré syndrome, myelitis
- Rare cardiac (myocarditis) and ocular (uveitis, retinitis) involvement
- Severe neonatal disease if vertical transmission occurs around delivery
- Case fatality rate is low overall but increased in neonates, elderly patients, and those with significant comorbidities
Prognosis
Overall mortality is low. The major source of long-term morbidity is chronic joint disease, which can significantly impair quality of life and function, making early recognition and appropriate anti-inflammatory management important.
CHIKungunya = CHronic joint pain, Incapacitating arthralgia, Known for Aedes mosquitoes
Practice questions
1. A 34-year-old woman returns from a trip to Southeast Asia with 4 days of fever and severe, symmetric pain in her wrists, fingers, and ankles that makes it difficult to grip objects. She also has a maculopapular rash on her trunk. Platelet count is mildly decreased but there is no bleeding. Which of the following is the most likely diagnosis?
2. A 2-day-old neonate born to a mother who had fever and joint pain just before delivery presents with lethargy, poor feeding, and a diffuse rash. The mother's symptoms began 2 days before delivery and she tested positive for chikungunya virus by RT-PCR. What is the most likely mechanism of transmission to the infant?
3. A 45-year-old man presents with fever and polyarthralgia 5 days after returning from an area with an active chikungunya outbreak. He wants to take ibuprofen for the joint pain. Dengue has not yet been excluded. What is the most appropriate next step?
Frequently asked questions
What causes chikungunya?
Chikungunya is caused by chikungunya virus (CHIKV), an alphavirus spread through the bite of infected Aedes aegypti or Aedes albopictus mosquitoes. These are the same day-biting mosquitoes that transmit dengue and Zika. Outbreaks typically occur in tropical and subtropical regions, often increasing after rainy seasons when mosquito populations grow.
What are the first symptoms of chikungunya?
The first symptoms are usually sudden high fever and severe joint pain, often starting abruptly within 3-7 days of a mosquito bite. Headache, muscle aches, and a maculopapular rash commonly follow. The joint pain is often the most distinctive and debilitating feature, frequently affecting hands, wrists, ankles, and feet symmetrically.
How is chikungunya diagnosed?
Chikungunya is diagnosed using RT-PCR to detect viral RNA in blood during the first week of illness, or IgM/IgG serology after about day 5 when antibodies develop. Diagnosis also relies on a compatible clinical picture (fever plus severe arthralgia) and a history of travel to or residence in an area with mosquito-borne virus transmission.
Is chikungunya curable?
The acute infection is self-limited and most people recover within one to two weeks, but there is no specific antiviral cure. Treatment is supportive, using fluids and pain relievers. A significant portion of patients, however, develop chronic joint pain lasting months or longer, which is managed with anti-inflammatory medications rather than cured outright.
Chikungunya vs dengue — what is the difference?
Both are mosquito-borne viral illnesses spread by Aedes mosquitoes and can look similar early on, but chikungunya causes more severe and prolonged joint pain, while dengue more commonly causes significant thrombocytopenia, bleeding risk, and potential plasma leakage leading to shock. Because they overlap clinically and can co-circulate, laboratory testing is often needed to distinguish them, especially before starting NSAIDs.
Key drugs
Related conditions and differentials
Sources and further reading
StatPearls (NCBI Bookshelf)MedlinePlusWHO ICD-10: A92.0
Educational content for medical students, prepared by the WhiteCoat Pro editorial team with AI assistance; every page is reviewed by a second AI model for factual errors. It is not medical advice and does not replace the product label, local guidelines or a clinician.