Impact of Project Wolbachia - Singapore on Dengue Incidence

Conditions

Dengue

Brief summary

The study is a cluster-randomised controlled trial set in Singapore, to assess if the deployment of male Wolbachia-infected Aedes aegypti mosquitoes can reduce dengue incidence in intervention clusters.

Detailed description

The study is designed as a parallel, two-arm, non-blinded cluster-randomised controlled trial to be conducted in high-rise public housing estates in Singapore. The aim is to determine whether large-scale deployment of male Wolbachia-infected Ae. aegypti mosquitoes can significantly reduce dengue incidence in intervention clusters. The investigators will use the cluster-randomised design, with the study area comprising 15 clusters with a total area of 10.9 km2, covering approximately 722,000 residents in 1,700 apartment blocks. Eight clusters will be randomly selected to receive the intervention, while the other seven will serve as non-intervention clusters. Intervention efficacy will be estimated through two primary endpoints: (1) odds ratio of Wolbachia exposure distribution (i.e. probability of living in an intervention cluster) among laboratory-confirmed reported dengue cases compared to test-negative controls, and (2) laboratory-confirmed reported dengue counts normalized by population size in intervention versus non-intervention clusters.

Chang CC, Lim JT, Chong CS, Mailepessov D, Dickens B, Zhai Y, Deng L, Lee C, Tan LY, Chain G, Zulkifli MF, Liew JWK, Vasquez K, Chau ML, Ng Y, Lee V, Sim S, Tan CH, Ng LC.

2026-09-10

10.1016/j.ebiom.2026.106476

Dengue Suppression by Male Wolbachia-Infected Mosquitoes.

Lim JT, Chong CS, Chang CC, Mailepessov D, Dickens B, Lai YL, Deng L, Lee C, Tan LY, Chain G, Zulkifli MF, Liew JWK, Vasquez K, Chau ML, Ng Y, Lee V, Wong JCC, Sim S, Tan CH, Ng LC, Project Wolbachia–Singapore Consortium.

2026-02-11

10.1056/nejmoa2503304

Update to: Assessing the efficacy of male Wolbachia-infected mosquito deployments to reduce dengue incidence in Singapore.

Lim JT, Mailepessov D, Chong CS, Chang CC, Dickens B, Lai YL, Deng L, Lee C, Tan LY, Chain G, Ho SH, Zulkifli MF, Liew J, Vasquez K, Lee V, Wong JCC, Sim S, Tan CH, Ng LC.

2024-06-206 citations

10.1186/s13063-024-08148-z

Assessing the efficacy of male Wolbachia-infected mosquito deployments to reduce dengue incidence in Singapore: study protocol for a cluster-randomized controlled trial

Janet Ong, Soon Hoe Ho, Stacy Soh, Yvonne Y. Y. Wong, Youming Ng et al. (15 authors)

Trials2022-12-1727 citations

10.1186/s13063-022-06976-5

Interventions

BIOLOGICALBiological (Male Wolbachia-infected Aedes aegypti)

Releases of male Wolbachia-infected Aedes aegypti mosquitoes

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

PREVENTION

Masking

NONE

Intervention model description

Parallel, two-arm, non-blinded cluster-randomised controlled trial

Eligibility

Sex/Gender

ALL

Healthy volunteers

No

Inclusion criteria

* Dengue-suspected patients living in the intervention and non-intervention clusters whose blood samples are collected by a national network of diagnostic laboratories that support private clinics, public polyclinics, or public/private hospitals. * Test positive cases: Patients with virologically confirmed DENV infection through RT-qPCR, testing positive for NS1 antigen or IgM. A positive test for any of the three assays would classify the patient as a dengue case. * Test negative controls: Patients with negative test results for DENV through RT-qPCR, NS1 antigen ELISA, or DENV IgM.

Design outcomes

Primary

Measure	Time frame	Description
Odds ratio of Wolbachia exposure distribution among laboratory-confirmed reported dengue cases compared to test-negative controls	Up to 3 years	Dengue cases and dengue test-negative controls data will be obtained from the national surveillance network of diagnostic laboratories which receive samples for dengue testing.
Laboratory-confirmed reported dengue case counts normalized by population size in intervention versus non-intervention clusters	Up to 3 years	Dengue cases data will be obtained from the national surveillance network of diagnostic laboratories which receive samples for dengue testing.

Secondary

Measure	Time frame	Description
Prevalence of Ae. aegypti/Ae. albopictus mosquitoes	Up to 3 years	Data will be obtained from the national gravitrap surveillance system
Public Attitudes, Perceptions & Knowledge (APK) of Wolbachia and other vector control interventions	Up to 3 years	Sentiment surveys pre-trial and during the course of the trial, using true/false and Likert-type scales. Higher scores mean better outcomes.

Countries

Singapore

Outcome results

None listed