Dengue fever, Hawaii, 2001-2002.

Area of Science:

• * Epidemiology and Public Health
• * Infectious Diseases
• * Medical Entomology

Background:

• * Autochthonous dengue virus transmission was last documented in Hawaii in 1944.
• * A resurgence of dengue fever was suspected in Hawaii in September 2001.

Purpose of the Study:

• * To investigate and confirm dengue virus infections in Hawaii.
• * To identify the dengue virus serotype and its origin.
• * To assess the role of mosquito vectors in local transmission.

Main Methods:

• * Active surveillance for denguelike illness in Hawaii residents.
• * Laboratory confirmation of dengue virus infections.
• * Dengue virus isolation and serotyping.
• * Phylogenetic analysis of viral isolates.
• * Mosquito surveillance for vector species (Aedes albopictus, Aedes aegypti).

Main Results:

• * 1,644 individuals with denguelike illness were evaluated; 122 (7%) had laboratory-confirmed dengue infections.
• * Dengue virus serotype 1 was isolated from 15 patients.
• * Phylogenetic analysis indicated a close relationship between Hawaiian isolates and those from Tahiti, French Polynesia.
• * Aedes albopictus was prevalent on surveyed islands; Aedes aegypti was absent.
• * Three autochthonous cases were linked to travelers returning from French Polynesia.

Conclusions:

• * The 2001 dengue outbreak in Hawaii was caused by dengue virus serotype 1, likely introduced from French Polynesia.
• * Aedes albopictus mosquitoes played a role in local dengue transmission.
• * The findings emphasize the critical need for ongoing vector surveillance and control, even in areas without recent disease activity.