To investigate nosocomial, non–vector-borne transmission of Dabie bandavirus (DBV) at a hospital in Zhejiang Province, China, using clinical, epidemiological, virological, and genomic evidence.
Approach:
Epidemiological investigation: Researchers conducted contact tracing and reviewed interviews and medical records for one index patient and five secondary cases, assessing clinical features, exposure type and duration, tick-bite history, and adherence to infection-control measures.
Laboratory and genomic examination: Clinical specimens underwent qRT-PCR, viral isolation in Vero cells, microneutralization testing, and whole-genome sequencing. Phylogenetic and sequence analyses were used to assess viral relatedness and evaluate differences between the index and secondary cases.
Key Findings:
The cluster comprised six laboratory-confirmed cases: one index patient, four exposed healthcare workers, and one patient who shared a ward with the index case without documented direct contact.
The four infected healthcare workers had provided invasive care without eye protection and developed symptoms 6 to 9 days after exposure.
Full-length genomes from the index case and secondary cases S4 and S5 clustered together within Clade II and showed high genetic identity, supporting a shared origin and nosocomial transmission.
DBV was successfully isolated from S4 and S5, and neutralizing antibody levels increased over time in monitored secondary cases.
Because environmental air sampling was unavailable, the route of transmission to the patient who shared the ward could not be definitively established.
Interpretation:
The convergence of contact tracing, viral isolation, phylogenetic clustering, near-absolute sequence identity, and clinical evidence supports human-to-human DBV transmission in the healthcare setting. The findings highlight infection risks associated with exposure to infectious fluids and suggest that risks within shared clinical spaces may be underestimated.
Limitations:
Whole-genome sequences were obtained from the index case and only two of the five secondary cases.
Environmental air sampling was unavailable, preventing confirmation of airborne transmission to the secondary patient without documented direct contact.
Functional assessment of the E421G substitution was limited to computational and structural modeling and requires experimental validation.
Transmission-associated substitutions require cautious interpretation because technical artifacts, low-frequency variants, and passage-associated changes may affect sequence analyses.
Conclusion:
This investigation documents a nosocomial cluster of human-to-human DBV transmission and demonstrates the value of integrating epidemiological tracing, viral isolation, neutralization assays, and whole-genome sequencing to reconstruct transmission chains and assess infection-control risks.
