Autochthonous dengue infections were last reported in
Hawaii in 1944. In September 2001, the Hawaii Department
of Health was notified of an unusual febrile illness in a res-ident with no travel history; dengue fever was confirmed.
During the investigation, 1,644 persons with locally
acquired denguelike illness were evaluated, and 122 (7%)
laboratory-positive dengue infections were identified;
dengue virus serotype 1 was isolated from 15 patients. No
cases of dengue hemorrhagic fever or shock syndrome
were reported. In 3 instances autochthonous infections
were linked to a person who reported denguelike illness
after travel to French Polynesia. Phylogenetic analyses
showed the Hawaiian isolates were closely associated with
contemporaneous isolates from Tahiti. Aedes albopictus
was present in all communities surveyed on Oahu, Maui,
Molokai, and Kauai; no Ae. aegyptiwere found. This out-break underscores the importance of maintaining surveil-lance and control of potential disease vectors even in the
absence of an imminent disease threat.