Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Intervention Strategies to Control and Prevent Disease Outbreaks Caused by Avian Influenza and Other Emerging Poultry Pathogens

Location: Exotic and Emerging Avian Viral Diseases Research Unit

Title: Role of poultry in the H7N9 influenza outbreaks in China

Authors
item PANTIN-JACKWOOD, MARY
item MILLER, PATTI
item SPACKMAN, ERICA
item SWAYNE, DAVID
item Costa-Hurtado, Mar -
item Susta, Leonardo
item SUAREZ, DAVID

Submitted to: Feedinfo News Service
Publication Type: Trade Journal
Publication Acceptance Date: April 20, 2014
Publication Date: April 20, 2014
Citation: Pantin Jackwood, M.J., Miller, P.J., Spackman, E., Swayne, D.E., Costa-Hurtado, M., Susta, L., Suarez, D.L. 2014. Role of poultry in the H7N9 influenza outbreaks in China. Feedinfo News Service. April 2014. Available: http://www.feedinfo.com.

Interpretive Summary: The outbreaks of H7N9 influenza in China have resulted in many human cases with a high fatality rate. Poultry is suspected as the source of infection based on virus sequence analysis and virus isolations from live poultry markets (LPM’s). What is not clear is which species of birds in these LPM’s are most likely to be infected and shedding enough virus to infect humans. Intranasal inoculation of chickens, Japanese quail, pigeons, Pekin ducks, Mallard ducks, Muscovy ducks, and Embden geese with a H7N9 virus resulted in infection of all species but no clinical signs. Virus shedding in quail, chickens and Muscovy ducks was much higher and prolonged than in the rest of the species. Quail effectively transmitted the virus to direct contacts but pigeons and Pekin ducks did not. In all species virus was detected at much higher titers from oropharyngeal swabs than cloacal swabs. The H7N9 virus outbreak clearly has an important poultry component but control of H7N9 influenza will be complicated by the lack of disease signs in poultry. Efforts in China have targeted LPM’s in an attempt to control the virus, but a better understanding of the contribution of poultry farms, wholesale markets, and the markets themselves in the maintenance of the virus is needed as well as continuous monitoring of influenza viruses in poultry for the prevention of future outbreaks.

Technical Abstract: The outbreaks of avian influenza A (H7N9) occurring in China in 2013 and 2014 have resulted in more than 370 human cases with a 30% fatality rate. Most of these infections are believed to result from exposure to infected poultry or contaminated environments as the viruses have been detected in avian species in the live poultry markets (LPM’s). Also, around 80% of human cases report a history of exposure to birds or LPM’s, and the viruses isolated from humans are genetically similar to those isolated from birds. Closure of LPM’s in affected provinces resulted in reduction of human cases and provided further evidence of the role of poultry in the spread of the virus. However, it’s not clear which species of birds are most likely to be infected and shedding sufficient levels of the virus to infect humans. Intranasal inoculation of chickens, Japanese quail, pigeons, Pekin ducks, Mallard ducks, Muscovy ducks, and Embden geese with a H7N9 virus resulted in infection but no clinical signs. Virus shedding in quail, chickens and Muscovy ducks was much higher and prolonged than in the rest of the species. Quail effectively transmitted the virus to direct contacts but pigeons and Pekin ducks did not. In all species virus was detected at much higher titers from oropharyngeal swabs than cloacal swabs. The H7N9 virus outbreak clearly had an important poultry component. Control of H7N9 influenza will be complicated by the lack of disease signs in poultry. Efforts in China have targeted LPM’s in an attempt to control the virus, but a better understanding of the contribution of poultry farms, wholesale markets, and the markets themselves in the maintenance of the virus is necessary. Continuous monitoring of influenza viruses in poultry is essential for prevention of future outbreaks.

Last Modified: 9/10/2014
Footer Content Back to Top of Page