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Dengue activity in Puerto Rico during an interepidemic period (1995-1997)
J G Rigau-Pérez1, A Ayala-López, A V Vorndam
1Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico 00920-3860, USA.
Abstract:
From 1995 to 1997 dengue was reported in Puerto Rico at an average annual rate of 1.75/1,000 population, compared to 6.73 in 1994, an epidemic year. Dengue virus serotypes 1 (DEN-1), -2, and -4 were isolated each year, with DEN-2 predominating in 1995 and 1996, and DEN-4 in 1997. From 1995 through 1997 incidence was highest (0.61-0.77/1,000) in persons under 30 years of age; males and females were equally affected. Among positive cases, 28.3% to 37.9% were hospitalized; 28.9% to 35.2% had hemorrhagic manifestations; at least 1.1% to 1.6% fulfilled the criteria for dengue hemorrhagic fever/dengue shock syndrome; and 0.2% to 0.3% died. Neither hurricane preparations (1995) nor widespread floods (1996) seem to have affected dengue incidence. Most municipalities with the highest laboratory-diagnosed dengue rates in 1995 were in the eastern foothills of the central mountains, an area relatively spared by the 1994 epidemic. In the next two years, at least half of the municipalities with the highest laboratory-diagnosed dengue rates were in the west. The most intense municipal outbreak of this period (DEN-2, Villalba, 1995, rate of 11.67/1,000) is described to highlight the importance of local conditions and epidemiologic history in determining the risk of dengue.
Insights
Dengue incidence in Puerto Rico decreased after 1994 but varied by location and year, with dengue virus serotypes 1, 2, and 4 circulating. Local conditions and past outbreaks influenced dengue risk.
Area of Science:
- * Epidemiology
- * Infectious Diseases
- * Public Health
Background:
- * Dengue fever is a significant public health concern in tropical and subtropical regions.
- * Puerto Rico experienced a dengue epidemic in 1994, necessitating ongoing surveillance.
- * Understanding dengue epidemiology is crucial for effective control strategies.
Purpose of the Study:
- * To analyze dengue incidence and characteristics in Puerto Rico from 1995 to 1997.
- * To identify demographic and geographic patterns of dengue virus circulation.
- * To investigate the impact of local conditions on dengue risk.
Main Methods:
- * Retrospective analysis of laboratory-diagnosed dengue cases reported in Puerto Rico between 1995 and 1997.
- * Isolation and identification of circulating dengue virus serotypes (DEN-1, DEN-2, DEN-4).
- * Geographic mapping of high-incidence municipalities and demographic analysis of affected populations.
Main Results:
- * Average annual dengue incidence decreased from 6.73/1,000 in 1994 to 1.75/1,000 during 1995-1997.
- * Dengue virus serotypes 1, 2, and 4 were isolated; DEN-2 predominated in 1995-1996, and DEN-4 in 1997.
- * Incidence was highest in individuals under 30; hospitalization rates ranged from 28.3% to 37.9%, with severe manifestations and mortality observed.
- * Geographic distribution of high-incidence areas shifted from eastern to western municipalities over the study period.
- * No significant impact of hurricane preparations or floods on dengue incidence was observed.
- * A notable outbreak in Villalba (DEN-2, 1995) highlighted the role of local factors and epidemic history.
Conclusions:
- * Dengue incidence in Puerto Rico declined post-1994 but remained a concern, with shifts in geographic hotspots.
- * The circulation of multiple dengue virus serotypes and their varying predominance underscore the risk of recurrent epidemics.
- * Local conditions and prior epidemic history are critical determinants of dengue risk at the municipal level.