After a 15-year period of low incidence, dengue has reemerged in Singapore in 
the past decade. We identify potential causes of this resurgence. A combination 
of lowered herd immunity, virus transmission outside the home, an increase in 
the age of infection, and the adoption of a case-reactive approach to vector 
control contribute to the increased dengue incidence. Singapore's experience 
with dengue indicates that prevention efforts may not be sustainable. For 
renewed success, Singapore needs to return to a vector control program that is 
based on carefully collected entomologic and epidemiologic data. Singapore's 
taking on a leadership role in strengthening disease surveillance and control in 
Southeast Asia may also be useful in reducing virus importation.