A togavirus (see virus) that is transmitted by mosquitoes and causes disease in humans characterized by fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue, and rash. Illness generally lasts a few days, before a full recovery, although joint pain may be prolonged in some cases. It was first reported in southern Tanzania in 1952 and has since occurred in over 60 countries in Africa, Asia, Europe, and the Americas. The name derives from the Makonde language and means ‘to become contorted’, reflecting the stooped posture of infected persons.