The world's first case of a wild avian influenza A H6N1 virus has been confirmed in a 20-year-old Taiwanese woman. Scientists who analyzed the virus found it has a genetic mutation, allowing it to get into human cells and cause infection.
Results of their findings were published in a study in The Lancet Respiratory Medicine.
The woman entered a hospital in central Taiwan in May 2013 with flu-like symptoms and difficulty breathing. Her doctors say she fully recovered after treatment with oseltamivir (Tamiflu).
Although the woman worked in a delicatessen, she had not been in close proximity to poultry or wild birds and had not traveled abroad for 3 months before the infection.
Avian influenza A H6N1 is commonly in wild and domestic avian species, but this is the first confirmed human infection with this virus, researchers say.
Samples collected from two poultry breeding sites near the woman's home did not contain the H6N1 virus, so the source of the infection is still unknown.
When the scientists ran tests on throat-swab samples, they found an unclassified subtype of influenza A virus. Further genome sequencing revealed that the virus was a new H6N1 avian virus.
Lead author Dr. Ho-Sheng Wu, from the Centers for Disease Control in Taiwan, says that after running a genetic analysis, they found the virus "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."
A mutation in the hemagglutinin - which researchers say is a binding protein on the virus' surface that allows it to access human cells and cause infection - is what makes the virus preferential to SAα-2,6 receptors in the upper airway.
The team says this allows the virus to become even more infectious to humans.
'Preparedness for pandemic needed'
There were 36 people who came in close contact with the woman. Though six developed a fever or infection in the respiratory tract, none of the pathogens were identified, and H6N1 infection was ruled out.
H6N1 is commonly found in wild and domestic birds in many countries, says Dr. Wu, adding, however, that their findings "suggest that a unique group of H6N1 viruses with the human adaption marker G228S have become endemic and predominant in poultry in Taiwan."
Dr. Wu continues:
"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."
In a linked comment to the study, Marion Koopmans, from the National Institute for Public Health and the Environment in the Netherlands, asks:
"What would it take for these viruses to evolve into a pandemic strain? And an overriding question is if it is time to review our approaches to influenza surveillance at the human-animal interface? We surely can do better than to have human beings as sentinels."
The researchers conclude their report by writing that it "highlights the continuous need for preparedness for a pandemic of unpredictable and complex avian influenza."
Medical News Today recently reported that the immune system has the capacity to "remember" viruses and store the details in B memory cells. A study outlined how the flu virus takes advantage of this by wiping out the immune system's first wave of defense against virus re-infection.