High Prevalence of Highly Pathogenic Avian Influenza: A Virus in Vietnam's Live Bird Markets

Duy Tung Dao; Kristen K Coleman; Vuong N Bui; Anh N Bui; Long H Tran; Quy D Nguyen; Son Than; Laura A Pulscher; Lyudmyla V Marushchak; Emily R Robie; Hung Nguyen-Viet; Phuc Duc Pham; Nathaniel C Christy; John S Brooks; Huy C Nguyen; Adam M Rubrum; Richard J Webby; Gregory C Gray

doi:10.1093/ofid/ofae355

High Prevalence of Highly Pathogenic Avian Influenza: A Virus in Vietnam's Live Bird Markets

Open Forum Infect Dis. 2024 Jul 11;11(7):ofae355. doi: 10.1093/ofid/ofae355. eCollection 2024 Jul.

Authors

Duy Tung Dao¹, Kristen K Coleman^{2

3

4}, Vuong N Bui¹, Anh N Bui¹, Long H Tran¹, Quy D Nguyen¹, Son Than^{1

2}, Laura A Pulscher⁵, Lyudmyla V Marushchak⁵, Emily R Robie⁶, Hung Nguyen-Viet⁷, Phuc Duc Pham⁸, Nathaniel C Christy⁹, John S Brooks⁹, Huy C Nguyen⁹, Adam M Rubrum¹⁰, Richard J Webby¹⁰, Gregory C Gray^{5

11

12

13}

Affiliations

¹ Virology Department, National Institute of Veterinary Research, Hanoi, Vietnam.
² Programme in Emerging Infectious Diseases, Duke-NUS Medical School, National University of Singapore, Singapore, Singapore.
³ Department of Global, Environmental, and Occupational Health, University of Maryland School of Public Health, College Park, Maryland, USA.
⁴ Department of Veterinary Medicine, College of Agriculture and Natural Resources, University of Maryland, College Park, Maryland, USA.
⁵ Division of Infectious Diseases, Department of Medicine, University of Texas Medical Branch, Galveston, Texas, USA.
⁶ Global Health Institute, Duke University, Durham, North Carolina, USA.
⁷ International Livestock Research Institute, Hanoi, Vietnam.
⁸ Center for Public Health and Ecosystem Research, Hanoi University of Public Health, Hanoi, Vietnam.
⁹ U.S. Naval Medical Research Unit INDO PACIFIC, Singapore, Singapore.
¹⁰ Department of Host-Microbe Interactions, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
¹¹ Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA.
¹² Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA.
¹³ Department of Global Health, School of Public and Population Health, University of Texas Medical Branch, Galveston, Texas, USA.

Abstract

Background: In recent years, Vietnam has suffered multiple epizootics of influenza in poultry.

Methods: From 10 January 2019 to 26 April 2021, we employed a One Health influenza surveillance approach at live bird markets (LBMs) and swine farms in Northern Vietnam. When the COVID-19 pandemic permitted, each month, field teams collected oral secretion samples from poultry and pigs, animal facility bioaerosol and fecal samples, and animal worker nasal washes at 4 LBMs and 5 swine farms across 5 sites. Initially samples were screened with molecular assays followed by culture in embryonated eggs (poultry swabs) or Madin-Darby canine kidney cells (human or swine swabs).

Results: Many of the 3493 samples collected had either molecular or culture evidence for influenza A virus, including 314 (37.5%) of the 837 poultry oropharyngeal swabs, 144 (25.1%) of the 574 bioaerosol samples, 438 (34.9%) of the 1257 poultry fecal swab samples, and 16 (1.9%) of the 828 human nasal washes. Culturing poultry samples yielded 454 influenza A isolates, 83 of which were H5, and 70 (84.3%) of these were highly pathogenic. Additionally, a positive human sample had a H9N2 avian-like PB1 gene. In contrast, the prevalence of influenza A in the swine farms was much lower with only 6 (0.4%) of the 1700 total swine farm samples studied, having molecular evidence for influenza A virus.

Conclusions: This study suggests that Vietnam's LBMs continue to harbor high prevalences of avian influenza A viruses, including many highly pathogenic H5N6 strains, which will continue to threaten poultry and humans.

Keywords: avian influenza virus; highly pathogenic avian influenza virus; influenza virus; zoonosis; zoonotic influenza.