Dengue surge looms as dominant virus strain shifts, warns NEA

SINGAPORE: An imminent surge in dengue cases threatens Singapore, as mosquitoes have increasingly spread a previously dominant strain, DenV-1.

The National Environment Agency (NEA) reported a worrying increase in this strain over the recent months.

After DenV-3 serotype’s dominance that contributed to Singapore’s dengue outbreak in 2022 and remained significant during the first half of 2023, a sharp shift has been observed.

In July, DenV-1 cases stood at approximately 55%, a stark rise from the 17% of DenV-3 cases, the NEA informed on Wednesday.

“The spike in a once lesser prevalent dengue virus serotype signals alarm as past patterns show a surge in cases ensuing months later,” stated the agency.

As of September 5, the number of dengue cases reported in 2023 has surpassed 6,200. The previous year, 2022, saw 32,325 dengue cases, marking it the second-highest annual count. The highest ever reported was in 2020, with 35,315 cases.

Before the late 2021 emergence of the DenV-3 serotype, the dominant strains had been DenV-1 and DenV-2.

Dengue manifests in four distinct serotypes, which means an individual could be infected up to four times. Subsequent infections elevate the risk of severe dengue fever for the person.

The lesser-known DenV-3 strain had left many residents susceptible, mainly due to their unfamiliarity and lack of immunity.

Currently, 48 active dengue clusters are identified, with 13 being extensive clusters reporting 10 or more cases. Clusters located at Science Park Drive, reporting 29 cases, and Lentor Loop, with 24 cases, are witnessing rapid transmission rates.

Meanwhile, the cluster at Lorong 1 and Lorong 2 Toa Payoh remains the largest with 319 cases, showing signs of consistent transmission.

The NEA sounded the alert, “The rising dominance of Denv-1 amidst high weekly dengue statistics, persistent dengue clusters, and prevalent Aedes mosquito populations in several regions poses a significant risk of a dengue surge.”

To counteract this threat, the agency emphasized the importance of eliminating stagnant water sources. They also urged households and offices, especially those within active clusters, to adopt preventive measures.

These measures include regular use of insect repellent, wearing long-sleeved clothing, and deploying insecticides in house corners.

For those diagnosed with or suspected to have dengue, the NEA strongly recommends these preventive steps to halt the virus’s spread to mosquitoes and fellow residents.

In identified dengue clusters, around 68% of Aedes mosquito breeding sites were found in residential areas. 29% were located in public spaces, and the remaining sites were within construction zones and other areas.