Clinical Scorecard: Initial Molecular Detection of Tembusu Virus in Mosquitoes from Vietnam

At a Glance

Key Highlights

• The study provided the first mosquito-based molecular evidence of a TMUV-related virus in Vietnam.

• Researchers screened 10,658 mosquitoes representing 4 vector species and grouped into 586 pools.

• A TMUV draft genome was recovered from a pool of 25 Culex tritaeniorhynchus mosquitoes collected in rural southern Vietnam.

• The recovered sequence covered 6,764 bases, or 61.5% of the complete genome.

• The sequence clustered with TMUV strains from China, Thailand, Taiwan, and Vietnam associated predominantly with poultry hosts.

• Viral RNA detection did not establish the presence of infectious virus or demonstrate mosquito vector competence.

Guideline-Based Recommendations

This molecular surveillance study did not establish clinical or public health guidelines for TMUV testing, prevention, or management.

Diagnosis

• Mosquito pools were screened for flaviviruses using broad-range RT-PCR targeting the NS5 region.

• Flavivirus-reactive amplicons underwent Sanger sequencing, and 1 pool with a TMUV-like signal underwent viral metagenomic sequencing.

• Most RT-PCR–reactive bands could not be confirmed by Sanger sequencing and were treated as unconfirmed screening signals.

• These research methods were not evaluated as diagnostic tests for avian or human infection.

Management

• The study did not evaluate treatment, vaccination, or mosquito-control interventions.

• Detection of TMUV-related RNA does not establish that the sampled mosquitoes contained infectious virus or were capable of transmitting it.

• The authors proposed combining mosquito surveillance with sampling of domestic ducks, wild birds, and poultry farms in future studies.

• TMUV-specific assays, virus isolation, and complete-genome sequencing are needed for more detailed characterization.

Monitoring & Follow-up

• Future research should use longitudinal mosquito surveillance to assess temporal and geographic patterns.

• Surveillance across agricultural, wetland, rural, and other ecological settings may help characterize mosquito–avian interfaces.

• Complete-genome sequencing would permit more comprehensive analysis of genomic variation.

• The study was not designed to estimate TMUV prevalence, geographic distribution, seasonality, or vector competence.

Risks

• TMUV is primarily associated with disease in ducks, although other avian hosts may also be affected.

• Rice cultivation, wetlands, irrigation systems, and duck rearing may create ecological interfaces between mosquitoes and avian hosts.

• The detected RNA suggests a possible mosquito-associated transmission cycle but does not prove transmission.

• The direction and timing of regional viral spread could not be determined from the available phylogenetic data.

Patient & Prescribing Data

No patients were enrolled, and no human or avian clinical specimens were analyzed. The study examined 10,658 female mosquitoes collected across Vietnam during 2022–2023.

The study did not evaluate medications, prescribing practices, or treatment outcomes.

Clinical Best Practices

• Interpret detection in field-caught mosquitoes as molecular evidence of viral RNA rather than proof of infectious virus or vector competence.

• Confirm broad-range RT-PCR signals through sequence-based methods.

• Avoid treating unconfirmed PCR-reactive bands as definitive flavivirus detections.

• Account for uneven representation of mosquito species, regions, seasons, and habitats when interpreting surveillance findings.

• Support longitudinal mosquito and avian-host sampling, virus isolation, and complete-genome sequencing.

Related Resources & Content

1. First Mosquito-Based Molecular Evidence of Tembusu Virus in Vietnam — Loc DH, Sulesco T, Tóth GE, et al. International Journal of Infectious Diseases. 2026;170:108927. doi:10.1016/j.ijid.2026.108927.

2. Isolation and Characteristics of Tembusu Virus From Ducks in Southern Vietnam — Quoc CN, Thai BP, Anh VD, et al. European Poultry Science. 2024;88:1–11. doi:10.1399/eps.2024.401.

3. Duck Tembusu Virus in North Vietnam: Epidemiological and Genetic Analysis Reveals Novel Virus Strains — Dong HV, Tran GTH, Vu TTT, et al. Frontiers in Veterinary Science. 2024;11:1366904. doi:10.3389/fvets.2024.1366904.

4. Identification of the Tembusu Virus in Mosquitoes in Northern Thailand — Hamel R, Vargas REM, Rajonhson DM, et al. Viruses. 2023;15:1447. doi:10.3390/v15071447.