A "mild" outbreak of dengue, a viral disease transmitted by mosquitoes, is waning in Puerto Rico and Jamaica,and recently began occurring in the Bahamas, according to the U.S. Public Health Service. Haiti and the Dominican Republic, which share an island, had earlier begun "surveillance for dengue" and the Dominican Republic has stared a mosquito spraying program.

"We do not tell people not to go" on vacation to the three islands where the disease has been reported, said Dr. Marjorie Pollack of the Bureau of Epidemiology, Center for Disease Control, Atlanta. "If they are concerned they should use mosquito repellent."

According to a World Health Organization spokesman, "effective control measures are well under way in the Bahamas," and the outbreak appears to be confined to New Providence Island.

In Advisory Memorandum No. 45, the CDC noted that "no licensed vaccine against dengue" exists. This is "a viral disease transmitted by mosquitoes and is characterized by sudded onset, high fever, severe headache, joint and muscle pain, and frequently rash . . . the patient may experience a prolonged recovery with fatigue and depression for several weeks." Incubation period is about two weeks.

Aedes Aegypti, the carrier mosquito, "is active in the daytime . . . Spraying with insecticides and reducing breeding sites in Nassau and other areas have been undertaken . . ." the CDC reported. Puerto Rico and Jamaica also launched mosquito-control efforts. With the mosquito "prevalent throughout the Caribbean, previous dengue epidemics have spread from island to island (but) severe disease was not seen," the CDC said.