For the first time, scientists have detected a wild strain of bird flu virus - which they thought could not infect humans - in a young Taiwanese woman.
"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 SA alpha-2,6 found in the human upper respiratory tract, potentially enabling adaptation of the virus to human cells," said lead author Dr Ho-Sheng Wu from the Centres for Disease Control in Taiwan.
The woman from central Taiwan was admitted to a hospital with flu-like symptoms and shortness of breath in May. She responded to treatment with oseltamivir (Tamiflu) and has since fully recovered, 'Medical Xpress' reported.
Tests on throat-swab samples indicated an unclassified subtype of influenza A virus. 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.
The virus had a mutation (G228S) in the haemagglutinin - 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 SA alpha-2,6 receptors in the upper airway and enable the virus to become more infectious to humans.
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. The source of infection remains unknown.
Of 36 close contacts, six developed a fever or respiratory-tract infection, but none of the causative pathogens were identified, although H6N1 infections were ruled out.
Additionally, no H6N1 virus was found in samples collected from two poultry breeding sites near the patient's home.
"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," Wu said.
The study was published in the journal Lancet Respiratory Medicine.
