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Epidemiologic Notes and Reports Dengue Fever in Puerto Rico -- 1981

An outbreak of dengue fever took place in Puerto Rico in the late summer and fall of 1981. In this period, almost 7,000 cases of dengue-like illness were reported to the Puerto Rico Health Department. Numbers of cases of dengue-like illness began increasing in August, reached a peak in mid-October, and declined steadily thereafter (Figure 2). Generally, throughout this period, 50% of the paired serum specimens tested at CDC were positive for dengue. Cases were reported from all parts of the island, but the areas reporting the highest proportion of cases were districts outside the San Juan metropolitan area. No deaths or illnesses meeting World Health Organization criteria for dengue hemorrhagic fever were documented during the outbreak. However, sporadic hemorrhagic manifestations occurred among patients with confirmed dengue infection for whom the clinical and laboratory data were incomplete.

The Puerto Rico Health Department, in association with other government agencies, organized an extensive island-wide source-reduction and educational campaign in the early phases of the outbreak. By December 2, CDC had isolated 114 dengue type 1 viruses and 1 dengue type 4 virus. However, by late December, dengue type 4 was the predominant virus being isolated, and by mid-January 1982, more than 40 such isolates had been obtained. Reported by A Hernandez-Torres, MD, Environmental Health, Puerto Rico Dept of Health; Dengue Br, Vector-Borne Viral Diseases Div, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The last major outbreak of dengue in Puerto Rico was in 1978 when type 1 was the prevailing virus; apparently, a large susceptible population remained after that outbreak. Outbreaks of dengue occurred in Puerto Rico in 1963-1964 (type 3), 1968-1969 (type 2), 1975 (type 2), and 1977 (types 2 and 3).

Dengue type 4 was reported for the first time in the Caribbean in the spring of 1981 from St. Barthelemy and St. Martin (1). Subsequently, dengue type 4 was confirmed in Dominica, Guadaloupe, St. Thomas, Curacao, Belize, Haiti, and Jamaica, as well as Puerto Rico. The possibility exists that an outbreak of dengue type 4 could occur in Puerto Rico in 1982.


  1. CDC. Dengue type 4 infections in U.S. travelers to the Caribbean. MMWR 1981;30:249-50.

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