Dandy fever: An acute mosquito- borne viral illness of sudden onset that usually follows a benign course with headache, fever, prostration, severe joint and muscle pain, swollen glands (lymphadenopathy) and rash. The presence (the ôdengue triadö) of fever, rash, and headache (and other pains) is particularly characteristic. Better known as dengue, the disease is endemic throughout the tropics and subtropics. It goes by other names including breakbone fever. Victims of dengue often have contortions due to the intense joint and muscle pain. Hence, the name ôbreakbone fever.ö Slaves in the West Indies who contracted dengue were said to have ôdandy feverö because of their postures and gait.