Modelling the control strategies against dengue in Singapore

TLDR

Dengue cases in Singapore peaked in 2004–2005, yet the causes of this surge remain unclear. The authors developed a seasonal dengue transmission model to replicate the 2004–2005 epidemics. Using the model, they simulated various control strategies and found that adult mosquito killing is the most effective during an outbreak. The results indicate that larvicide alone prevents resurgence, while a combined adulticide–larvicide approach—applied during the outbreak and followed by larvicide maintenance—greatly reduces early case numbers.

Abstract

SUMMARY Notified cases of dengue infections in Singapore reached historical highs in 2004 (9459 cases) and 2005 (13 817 cases) and the reason for such an increase is still to be established. We apply a mathematical model for dengue infection that takes into account the seasonal variation in incidence, characteristic of dengue fever, and which mimics the 2004–2005 epidemics in Singapore. We simulated a set of possible control strategies and confirmed the intuitive belief that killing adult mosquitoes is the most effective strategy to control an ongoing epidemic. On the other hand, the control of immature forms was very efficient in preventing the resurgence of dengue epidemics. Since the control of immature forms allows the reduction of adulticide, it seems that the best strategy is to combine both adulticide and larvicide control measures during an outbreak, followed by the maintenance of larvicide methods after the epidemic has subsided. In addition, the model showed that the mixed strategy of adulticide and larvicide methods introduced by the government seems to be very effective in reducing the number of cases in the first weeks after the start of control.