ATLANTA (AP) - Cases of dengue fever, a mosquito-borne tropical disease marked by excruciating muscle and joint pain, rose sharply in the United States from 1993 to 1998, the government said. Increased travel, especially to the Caribbean and Central America, led to the dramatic rise, the Centers for Disease Control and Prevention said Thursday. The CDC recorded 90 cases of imported, laboratory-confirmed cases of dengue fever in 1998, up from a total of 46 in 1993-94. Dengue fever is characterized by the sudden onset of high fever, severe headaches, severe joint and muscle pain, nausea, vomiting and a rash. Dengue, also called break-bone fever, is transmitted by the bite of infected Aedes aegypti mosquitoes.