Chikungunya — DTM&H MCQ

Correct answer: A — Chikungunya

The correct answer is A, chikungunya. This presentation of abrupt-onset fever, rash and severe, symmetrical polyarthralgia affecting small joints (wrists, ankles) following heavy mosquito exposure on Reunion Island is classic for chikungunya, which is endemic and epidemic across the Indian Ocean islands via Aedes mosquitoes. A negative dengue test in a febrile traveller from this region should immediately prompt consideration of chikungunya as the other major arbovirus circulating in the same vector and geography. The hallmark distinguishing feature is that the arthralgia is disproportionately severe relative to the systemic illness and characteristically persists for weeks to months after the fever resolves, unlike dengue or Zika. This pattern of incapacitating, persistent joint pain outlasting the febrile phase is the key clinical clue used to differentiate chikungunya from other arboviral and non-arboviral causes. Why the other options are wrong: B. Zika virus infection: Zika typically causes a milder illness with maculopapular rash and conjunctivitis, and arthralgia is usually mild and transient rather than severe and persistent. E. Acute rheumatic fever: This follows streptococcal pharyngitis, not mosquito exposure, and causes a migratory large-joint arthritis with other Jones criteria features, not a mosquito-associated fever-rash-arthralgia triad. C. Viral hepatitis E: Hepatitis E presents with jaundice, malaise and deranged liver function, not an acute mosquito-borne fever-rash-arthralgia syndrome. D. Rickettsial spotted fever: Spotted fever typically features an eschar at the tick bite site and follows tick, not mosquito, exposure, with rash often vasculitic rather than the classic maculopapular chikungunya rash. Key point: Severe, symmetrical polyarthralgia that persists after the fever settles, in a mosquito-exposed traveller with negative dengue testing, points strongly to chikungunya.

Reference: UKHSA/NaTHNaC TravelHealthPro, Chikungunya factsheet, 2025, https://travelhealthpro.org.uk/factsheet/27/chikungunya