This article is more than 5 years old. Information may no longer be current.
Migratory waterfowl may help spread novel H5N6 viruses in China
Click Here to Manage Email Alerts
New research suggests that migratory waterfowl may help spread novel H5N6 avian influenza viruses in China.
According to researchers, H5N6 viruses were detected in fecal samples from three of the birds before the first human case of infection was reported in the country.
“Genetic and phylogenetic analyses revealed that these three novel viruses were closely related to the H5N6 virus that has caused human infections in China since 2014,” the researchers wrote in Nature Scientific Reports.
Three waterfowl infected with novel H5N6 viruses
The first human case of H5N6 infection was reported and confirmed in Sichuan Province in May 2014, according to the researchers. The patient, who died, was a poultry dealer who worked in a live poultry market — a risk factor for contracting influenza A viruses.
Migratory waterfowl are thought to be natural reservoirs of avian influenza viruses (AIVs), which are carried in their intestinal tract and excreted in high concentrations, according to the researchers. Because domestic poultry may contract AIVs from migratory waterfowl via feces or contaminated water through the sharing of common feeding sites around wetlands, there is a danger that H5N6 may be spread in areas over long distances, they said.
Before the patient in China was reported to have contracted H5N6, surveillance of AIVs in wild birds showed that three waterfowl in Chenhu wetlands, Hubei Province, were infected with three novel H5N6 viruses. Two of the hosts were identified only as migratory waterfowl; the third was a type of duck, Anas crecca.
Phylogenic reconstruction showed multiple reassortment events in the evolution of the viruses, and phylogenic analysis traced them to southern China, the researcher said. They were spread to other areas via eastern China, where reassortment may have occurred during 2012-2013, they wrote. The research found that the hemagglutinin originated from the H5N2 AIV and the neuraminidase from H6N6. All six internal genes were derived from avian H5N1 viruses.
“A receptor-binding test showed that H5N6 viruses from migratory waterfowl had human-type receptor-binding activity, suggesting a potential for transmission to humans,” they wrote. “These data suggest that migratory waterfowl may play a role in the dissemination of novel H5N6 viruses.”
Highly pathogenic AIVs do not persist in wild birds
Robert G. Webster
Migratory waterfowl from Asia also were implicated in the 2014-2015 outbreak of H5 avian influenza A virus in North American poultry farms. However, new research published in the Proceedings of the National Academy of Sciences suggests that highly pathogenic influenza viruses do not persist in wild birds and that they are not an ongoing source of such viruses in domestic poultry.
Robert G. Webster, PhD, emeritus member infectious diseases department at St. Jude Children’s Research Hospital, and colleagues analyzed throat swabs and other biological samples from 22,892 aquatic birds in the U.S. and Canada that were collected from January 2014 through December 2015, and detected no highly pathogenic AIVs. Further, they found no highly pathogenic AIVs while examining historical records of more than 100,000 North American wild birds dating back 43 years.
Webster said existing immunity in wild birds might be one explanation for the findings.
“The findings provide a scientific basis for the decision by officials to use culling and quarantines to stop the 2014-2015 outbreak in domestic poultry,” he said in a news release. “Now, research is needed to identify the mechanism that has evolved in these wild birds to disrupt the perpetuation of highly pathogenic influenza.” – by Gerard Gallagher
Disclosure: The researchers report no relevant financial disclosures.
Click Here to Manage Email Alerts