A 20-YEAR-old woman from Taiwan was diagnosed with bird flu after presenting to hospital with flu-like symptoms and shortness of breath this year.
The details of her case – the world’s first confirmed case of human infection with a wild avian influenza A H6N1 virus – are outlined by scientists from Taiwan in a report in The Lancet Respiratory Medicine today.
Lead author Dr Ho-Sheng Wu from the Centres for Disease Control in Taiwan explained:
A genetic analysis of the H6N1 virus identified in a 20-year-old woman shows a virus that has evolved the ability to target a receptor called SAα-2,6 found in the human upper respiratory tract, potentially enabling adaptation of the virus to human cells.
The woman, who was from central Taiwan, presented to a hospital with flu-like symptoms and shortness of breath in May 2013.
Doctors took throat-swab samples, and tests indicated an unclassified subtype of influenza A virus.
More tests and genome sequencing established that the virus was a novel avian-origin H6N1 virus that closely resembled chicken H6N1 viruses that have been circulating in Taiwan since 1972.
Thankfully, the woman responded to treatment with oseltamivir (Tamiflu) and has since fully recovered.
The medical staff discovered that the virus had a mutation (G228S) in the haemagglutinin – this is a binding protein on the surface of the virus that enables it to get into human cells and cause infection – that could increase its preference for human SAα-2,6 receptors in the upper airway.
This would enable the virus to become more infectious to humans.
It was discovered that the woman worked in a delicatessen, had not been abroad for three months prior to infection, or been in close proximity to poultry or wild birds.
To this day, the source of infection remains unknown.
Contact
Of 36 people who had close contact with the woman, six developed a fever or respiratory-tract infection, but none of the causative pathogens were identified, although H6N1 infections were ruled out.
No H6N1 virus was found in samples collected from two poultry breeding sites near the patient’s home.
Dr Wu explained that H6N1 is “a low pathogenic virus commonly found in wild and domestic birds across many continents”.
Our findings suggest that a unique group of H6N1 viruses with the human adaption marker G228S have become endemic and predominant in poultry in Taiwan. As these viruses continue to evolve and accumulate changes, they increase the potential risk of human infection. Further investigations are needed to clarify the potential threat posed by this emerging virus.
Marion Koopmans from the National Institute for Public Health and the Environment in the Netherlands commented on the report, noting that viruses with H6 subtype haemagglutinins are quite prevalent in wild birds and have often been identified in poultry.
He said that this results in generation of an “ever-expanding diverse set of influenza viruses through genetic reassortment”, and asked “what would it take for these viruses to evolve into a pandemic strain?”
An overriding question, said Koopmans, “is if it is time to review our approaches to influenza surveillance at the human-animal interface?”.
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