This article is more than 5 years old. Information may no longer be current.
Chicken, quail may be reservoirs for H7N9 in China
Among poultry species in China, chicken and quail seem to be particularly susceptible to H7N9 influenza virus infection and viral shedding, suggesting that these avian species may be reservoirs of the virus, according to recent findings.
These results indicate that chicken and quail may have played a role in transmission of H7N9 during the recent outbreak in China, according to the study results published in the Journal of Virology.
Mary J. Pantin-Jackwood, DVM, MS, PhD, ACPV, veterinary medical officer with the US Department of Agriculture, and colleagues intranasally inoculated several poultry species with the H7N9 influenza virus. Included in the study were chickens, Japanese quail, pigeons, Pekin ducks, Mallard ducks, Muscovy ducks and Embden geese.
The investigators collected oropharyngeal and cloacal swabs at 2, 4, 6, 8 and 11 days post-inoculation from 128 directly inoculated birds.
To assess the susceptibility of each type of bird to contact transmission, the researchers placed three uninfected birds in the same cage with directly inoculated birds in each group. Swabs were then collected from these birds 9 days after exposure to the birds infected by the researchers.
The researchers found that direct inoculation with H7N9 caused infection but no symptoms of disease. There was a much higher and more prolonged incidence of virus shedding in the quail and chickens than in the other species. Additionally, the quail transmitted the virus to cage-mates, but pigeons and Pekin ducks did not. Pigeons were found to be generally recalcitrant to infection and are not considered to be potential reservoirs of the virus.
According to study investigator David Suarez, of the US Department of Agriculture, because none of the infected birds became symptomatic, there is the possibility of a “silent carriage” of the disease.
“The silent carriage also creates a conflict between poultry producers, who want to preserve their flocks, versus the public health goals of eradicating the virus,” Suarez said. “The Chinese correctly closed the live bird markets where they had human infections, and that reduced the number of cases for a while. However, their efforts did not eradicate the virus, and it has returned for a second wave.”
Disclosure: This research was supported by US Department of Agriculture CRIS Project and with federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health.