Taiwan reports human case of H6N1

Researchers in Taiwan reported the first case of human infection with a wild influenza A H6N1 virus in The Lancet Respiratory Medicine.

The virus had a G228S mutation in the hemagglutinin that could enable the virus to become more infectious in humans, the researchers found.

“A genetic analysis of the H6N1 virus identified in a 20-year-old woman shows a virus that has evolved the ability to target the SA-alpha-2,6 receptor in the human upper respiratory tract, potentially enabling adaptation of the virus to human cells,” Ho-Sheng Wu, PhD, of the Centers for Disease Control in Taiwan, said in a press release.

The woman presented to a hospital in May with influenza symptoms and shortness of breath. Throat swab samples indicated an unclassified influenza A subtype. After performing genome sequencing, researchers found that it was a novel avian-origin H6N1 virus that closely resembled chicken H6N1 viruses that have circulated in Taiwan since 1972.

The woman worked in a delicatessen, had not been abroad for 3 months before infection, nor had been in close proximity to poultry or wild birds. Among 36 close contacts, six developed fever or respiratory tract infection, but H6N1 infections were ruled out. There also was no H6N1 virus found in samples taken from poultry breeding sites near the woman’s home.

“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. “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 an accompanying comment, Marion Koopmans, DVM, PhD, of the National Institute for Public Health and the Environment in the Netherlands, said viruses with the H6 subtype hemagglutinins are prevalent in wild birds, along with other influenza viruses. Through genetic reassortment, the number of influenza viruses continues to expand, Koopmans said, posing the question of what it would take for these viruses to evolve into a pandemic strain.

“An overriding question is if it is time to review our approaches to influenza surveillance at the human-animal interface?” Koopmans wrote. “We surely can do better than to have human beings as sentinels.”

For more information:

Koopmans M. Lancet Resp Med. 2013;doi:10.1016/S2213-2600(13)70233-9.

Wei S. Lancet Resp Med. 2013;doi:10.1016/S2213-2600(13)70221-2.

Disclosure: Koopmans and Wu report no relevant financial disclosures.