Question
Chikungunya virus.
Answer
Chikungunya virus is a mosquito-borne Alphavirus (family Togaviridae), a single-stranded positive-sense RNA virus transmitted to humans through the bite of infected Aedes mosquitoes (Aedes aegypti and Aedes albopictus — the same vectors responsible for transmitting dengue and Zika virus).
Clinical features: an acute febrile illness characterized by high fever and severe, often debilitating polyarthralgia/arthritis (the disease name derives from a Makonde word meaning “that which bends up,” referring to the stooped posture caused by severe joint pain), typically affecting small joints of the hands, wrists, ankles, and knees, often symmetrically; accompanied by a maculopapular rash and myalgia. Unlike dengue, significant haemorrhagic manifestations are uncommon, though co-infection with dengue can occur given the shared vector, and clinical differentiation can be difficult.
Distinctive feature: the joint symptoms, while usually resolving over days to weeks, can in a significant proportion of patients persist for months to years as chronic arthralgia/arthritis, a notable and clinically important distinguishing feature from most other arboviral febrile illnesses.
Laboratory diagnosis: RT-PCR for viral RNA — most sensitive in the first few days of illness (during the viraemic phase); serology — IgM ELISA (detectable from about day 5 of illness) and IgG for later/past infection; viral culture is possible but not routinely used for clinical diagnosis.
Treatment: no specific antiviral therapy is available; management is supportive (analgesics/NSAIDs for pain, avoiding aspirin until dengue co-infection with bleeding risk is excluded, similar to dengue management principles).
Prevention: mosquito control measures (source reduction, insecticides) and personal protective measures (repellents, protective clothing) — the same measures used against dengue and Zika, given the shared Aedes vector; no widely available licensed vaccine at present in most settings.