Singapore's Dengue Cases Decline: Analyzing Future Risks and Control Measures

SINGAPORE – The National Environment Agency (NEA) of Singapore reported a significant decrease in dengue cases, with only 2,219 cases recorded from January to June 5, 2025, compared to approximately 10,000 cases during the same period in 2024. This decline has raised questions about the effectiveness of ongoing control measures and whether it is too soon to celebrate the success of these initiatives. According to the NEA, the reduction in dengue cases is partly attributed to Project Wolbachia, an innovative initiative aimed at controlling the Aedes aegypti mosquito population by releasing lab-grown male mosquitoes infected with Wolbachia bacteria. This method has been implemented in high-risk areas, including Bukit Batok, Tampines, and Serangoon, with the goal of reaching 800,000 households by 2026. Studies have shown that these areas have seen a dramatic decrease in Aedes mosquito populations, with reductions of 80% to 90%, and residents are reported to be 75% less likely to contract dengue. Professor Ooi Eng Eong, an expert in emerging infectious diseases at Duke-NUS Medical School, described the integration of Project Wolbachia into Singapore’s vector control program as a “positive development” but cautioned against attributing the current trends solely to this initiative. He emphasized the cyclical nature of dengue epidemics, which typically occur in five to eight-year cycles. Factors such as population immunity to the four dengue virus serotypes and genetic changes in circulating viruses also play critical roles in dengue transmission. “Although the lower numbers in 2025 compared to 2024 are encouraging, it is premature to conclude that current control measures will effectively prevent future outbreaks,” said Professor Ooi, referencing the last major epidemic in 2022, which saw 32,325 cases, the second-highest annual total on record. In addition to Project Wolbachia, Professor Tikki Pang, a visiting professor at the Yong Loo Lin School of Medicine at the National University of Singapore (NUS), pointed out that seasonal variations and effective community engagement in mosquito control also contribute to the decline in cases. Singapore typically experiences fewer dengue cases outside the peak months from May to October. Community efforts to eliminate stagnant water, which serves as mosquito breeding sites, have been crucial in avoiding larger outbreaks. Despite the promising decline in cases, the NEA has warned that Singapore's relatively low population immunity, combined with a global rise in dengue cases, poses a risk for potential increases in dengue infections. The agency has reminded the public to remain vigilant, particularly as the May to October period approaches, which is often characterized by higher mosquito activity and dengue transmission. According to the World Health Organization (WHO), global dengue cases surged to over 13 million in 2024, more than double the 6.5 million reported in 2023. This alarming trend underscores the need for sustained efforts in both local and international contexts to control and combat dengue fever effectively. In conclusion, while the decline in dengue cases in Singapore is certainly a positive development, experts emphasize the importance of continued vigilance and robust public health measures. Ongoing research, community engagement, and adaptive control strategies will be critical in ensuring that Singapore can manage dengue risk effectively in the years to come.