Chikungunya — DTM&H MCQ

Correct answer: A — Chikungunya

The correct answer is A, Chikungunya. This viral infection, transmitted by Aedes mosquitoes and historically endemic to Réunion and the Indian Ocean islands, characteristically causes an abrupt onset of high fever with severe, often symmetrical polyarthralgia affecting small joints of the hands, wrists and ankles. Chikungunya is characterised by a sudden onset of fever usually accompanied by joint pain (arthralgia), and it can often be misdiagnosed as other viral illnesses such as dengue fever. The stem's key discriminators, negative dengue serology and joint pain persisting well beyond fever defervescence, reflect chikungunya's tendency to cause a prolonged, disabling arthropathy (sometimes lasting months to years) that distinguishes it from the more transient myalgia of dengue. Why the other options are wrong: D. Acute rheumatic fever: this follows streptococcal pharyngitis, causes migratory (not fixed symmetrical) large joint arthritis, and would show supporting evidence such as raised ASOT or carditis, not an abrupt febrile illness in a returning traveller from an endemic arbovirus region. B. Zika virus infection: typically produces a milder illness with conjunctivitis and a maculopapular rash, but arthralgia is usually mild and self-limiting, not the severe persistent polyarthralgia described. C. Dengue fever: explicitly excluded by negative testing in the stem, and dengue causes myalgia and retro-orbital pain rather than severe persistent small joint arthralgia after fever resolution. E. O'nyong-nyong fever: clinically similar alphavirus but geographically restricted to East Africa, not Réunion or the Indian Ocean islands. Key point: Severe, symmetrical, persistent small joint polyarthralgia outlasting the fever, with dengue excluded, in a traveller from the Indian Ocean region points to chikungunya.

Reference: UKHSA (GOV.UK), Chikungunya guidance, updated 2025, https://www.gov.uk/guidance/chikungunya