Spatial–temporal patterns of dengue in areas at risk of dengue hemorrhagic fever in Kaohsiung, Taiwan, 2002

OBJECTIVE: This study aimed to examine whether spatial-temporal patterns of dengue can be used to identify areas at risk of dengue hemorrhagic fever (DHF). METHODS: Three indices - probability of case-occurrence, mean duration per wave, and transmission intensity - were used to differentiate eight local spatial-temporal patterns of dengue during the 2002 epidemic in Kaohsiung, Taiwan. DHF densities (DHF cases/km(2) per 100 dengue cases) in each spatial-temporal typed area were compared. RESULTS: Areas with three high indices correlated with the highest DHF density: (1) high transmission intensity only; (2) long duration of wave only, and (3) high transmission intensity plus long duration of wave. However, cumulative incidences of dengue cases were not correlated with DHF densities. CONCLUSION: Three spatial-temporal indices of dengue could provide useful information to identify areas at high risk of DHF.