Chikungunya fever

• Epidemiology
  • Found primarily in tropical and subtropical regions (e.g., Central and South America, Caribbean, sub-Saharan Africa, Southern and Western Asia, and Europe)
• Etiology
  • Pathogen: Chikungunya virus (belongs to the alphavirus genus of the family Togaviridae)
  • Vectors: mosquitoes (Aedes aegypti and Aedes albopictus), possibly leading to coinfection with dengue
  • Route of transmission: Mosquito bite
• Clinical features
  • Symptoms are similar to those of dengue and Zika virus infection.
  • Incubation period: usually 3–7 days
  • Sudden onset fever (typically > 39°C)
  • Malaise
  • Severe bilateral polyarthralgia
  • Joint swelling (effusion, synovitis, periarticular edema)
  • Headache
  • Maculopapular rash
  • Other (less common): e.g., lymphadenopathy, bleeding (rare)

Tip

Chikungunya, dengue, and zika are all mosquito-borne diseases and similar in clinical features.

• Diagnostics
  • Key Labs:
    • Lymphopenia (very common). c
      • CHIKV directly infects peripheral blood mononuclear cells (PBMCs), including T-lymphocytes (CD4+ and CD8+) and dendritic cells.
      • Induces rapid, caspase-mediated programmed cell death (apoptosis) of lymphocytes.
    • Thrombocytopenia (usually mild).
    • Mildly elevated AST/ALT.
  • Confirmatory Testing (based on symptom duration):
    • < 6 days of onset: RT-PCR for viral RNA.
    • ≥ 6 days of onset: Serology (IgM anti-Chikungunya) via ELISA.