Affiliation:
1. Department of Animal Health Hanoi Vietnam
2. Influenza Division, National Center for Immunizations and Respiratory Disease Centers for Disease Control and Prevention Atlanta Georgia USA
3. Epidemic Intelligence Service Centers for Disease Control and Prevention Atlanta Georgia USA
4. National Center for Veterinary Diagnosis Department of Animal Health Hanoi Vietnam
5. Regional Animal Health Officer Number 6 Department of Animal Health Ho Chi Minh City Vietnam
Abstract
AbstractBackgroundHighly pathogenic avian influenza A(H5) human infections are a global concern, with many A(H5) human cases detected in Vietnam, including a case in October 2022. Using avian influenza virus surveillance from March 2017–September 2022, we described the percent of pooled samples that were positive for avian influenza A, A(H5), A(H5N1), A(H5N6), and A(H5N8) viruses in live bird markets (LBMs) in Vietnam.MethodsMonthly at each LBM, 30 poultry oropharyngeal swab specimens and five environmental samples were collected. Samples were pooled in groups of five and tested for influenza A, A(H5), A(H5N1), A(H5N6), and A(H5N8) viruses by real‐time reverse‐transcription polymerase chain reaction. Trends in the percent of pooled samples that were positive for avian influenza were summarized by LBM characteristics and time and compared with the number of passively detected avian influenza outbreaks using Spearman's rank correlation.ResultsA total of 25,774 pooled samples were collected through active surveillance at 167 LBMs in 24 provinces; 36.9% of pooled samples were positive for influenza A, 3.6% A(H5), 1.9% A(H5N1), 1.1% A(H5N6), and 0.2% A(H5N8). Influenza A(H5) viruses were identified January–December and at least once in 91.7% of sampled provinces. In 246 A(H5) outbreaks in poultry; 20.3% were influenza A(H5N1), 60.2% A(H5N6), and 19.5% A(H5N8); outbreaks did not correlate with active surveillance.ConclusionsIn Vietnam, influenza A(H5) viruses were detected by active surveillance in LBMs year‐round and in most provinces sampled. In addition to outbreak reporting, active surveillance for A(H5) viruses in settings with high potential for animal‐to‐human spillover can provide situational awareness.
Funder
Centers for Disease Control and Prevention
Subject
Infectious Diseases,Public Health, Environmental and Occupational Health,Pulmonary and Respiratory Medicine,Epidemiology