Live bird markets of Bangladesh: H9N2 viruses and the near absence of highly pathogenic H5N1 influenza

• Published in: PloS one 2011-04, Vol.6 (4), p.e19311-e19311
• Main Authors: Negovetich, Nicholas J, Feeroz, Mohammed M, Jones-Engel, Lisa, Walker, David, Alam, S M Rabiul, Hasan, Kamrul, Seiler, Patrick, Ferguson, Angie, Friedman, Kim, Barman, Subrata, Franks, John, Turner, Jasmine, Krauss, Scott, Webby, Richard J, Webster, Robert G
• Format: Article
• Language: English
• Subjects: Animals; Avian flu; Avian influenza; Avian influenza viruses; Bangladesh - epidemiology; Biology; Birds; Birds - virology; Chickens; Commerce; Epidemics; Geography; Health aspects; Health risks; Hemagglutination; Infection; Infections; Influenza; Influenza A Virus, H5N1 Subtype - classification; Influenza A Virus, H5N1 Subtype - isolation & purification; Influenza A Virus, H5N1 Subtype - pathogenicity; Influenza A Virus, H9N2 Subtype - classification; Influenza A Virus, H9N2 Subtype - isolation & purification; Influenza A Virus, H9N2 Subtype - pathogenicity; Influenza A Virus, H9N2 Subtype - physiology; Influenza in Birds - epidemiology; Influenza in Birds - virology; Markets; Morbidity; Outbreaks; Pandemics; Poultry; Poultry farming; Poultry industry; Prevalence; Serotyping; Surveillance; Veterinary Science; Viruses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0019311

Avian influenza surveillance in Bangladesh has been passive, relying on poultry farmers to report suspected outbreaks of highly pathogenic H5N1 influenza. Here, the results of an active surveillance effort focusing on the live-bird markets are presented. Prevalence of influenza infection in the birds of the live bird markets is 23.0%, which is similar to that in poultry markets in other countries. Nearly all of the isolates (94%) were of the non-pathogenic H9N2 subtype, but viruses of the H1N2, H1N3, H3N6, H4N2, H5N1, and H10N7 subtypes were also observed. The highly pathogenic H5N1-subtype virus was observed at extremely low prevalence in the surveillance samples (0.08%), and we suggest that the current risk of infection for humans in the retail poultry markets in Bangladesh is negligible. However, the high prevalence of the H9 subtype and its potential for interaction with the highly pathogenic H5N1-subtype, i.e., reassortment and attenuation of host morbidity, highlight the importance of active surveillance of the poultry markets.