A traveller returns from Kerala with three days of high fever, headache and a confluent maculopapular rash. Six weeks later he still has incapacitating symmetrical pain and stiffness of the wrists, ankles and small joints of the hands, with no thrombocytopenia and no bleeding. The most likely agent and its classification are:

• A Dengue virus, Flaviviridae
• B Chikungunya virus, Togaviridae (alphavirus) ✓
• C Kyasanur Forest disease virus, Flaviviridae
• D Zika virus, Flaviviridae

Explanation

Chikungunya is an Old World alphavirus of the family Togaviridae transmitted by Aedes aegypti and Aedes albopictus. Its hallmark is severe, symmetrical polyarthralgia that persists for weeks to months, caused by direct viral persistence in joint tissue and macrophages rather than immune complex deposition. Dengue causes retro-orbital pain, myalgia and thrombocytopenia with bleeding risk but not prolonged disabling arthritis, which discriminates the two clinically.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.