Risk factors for infection during a dengue-1 outbreak in Maui, Hawaii, 2001

Autochthonous dengue virus transmission, last identified in the state of Hawaii in 1945, was detected again in 2001. A seroepidemiological survey in a high-incidence community (Nahiku) and a nearby low-incidence community (Hana Subdivision) was implemented. The two communities studied differed in median household size (two vs. four persons), median lot size (2.8 vs. 0.8acres), proportion of households with mosquito larvae (81 vs. 28%) and incidence of recent infection (39% [28/72] vs. 1% [1/131]). The average number of reported anti-mosquito actions by residents of both locations remained low, and approximately 50% (42/80) of the inspected houses had larvae, evidencing the need for more effective community mosquito control. Logistic regression analysis of risk factors for infection in Nahiku identified residing in properties with birds in the house or yard as significantly associated with infection (odds ratio 7.0, 95% CI 1.7-28.5), probably as an indicator of unspecified environmental characteristics that were attractive to the vector. We documented that nearly 40% of Nahiku residents had acquired dengue locally in 2001 and that undetected dengue outbreaks had occurred in Hawaii. Our data suggest that ecological characteristics may help Hawaii health officials identify communities at increased risk of dengue infection.