There are three known cases of infection with this strain of avian influenza — all of them in China. A young boy developed severe pneumonia in April last year after eating chicken, while another child fell mildly ill in May after visiting a wet market where live poultry was sold.
The third patient, a 56-year-old woman from the southeastern coastal province of Guangdong, fell ill in February of this year. She was hospitalized for severe pneumonia in early March and died on March 16.
"The patient had multiple underlying conditions. She had a history of exposure to live poultry before the onset of the disease, and a history of wild bird presence around her home. No close contacts of the case developed an infection or symptoms of illness at the time of reporting," the UN health agency said.
Preliminary findings suggest that the woman was exposed to the virus at a live poultry market, WHO said. Environmental samples collected from the wet market where the patient spent time before the onset of illness came back positive.
"However, it is still unclear what the exact source of this infection is and how this virus is related to other avian influenza A(H3N8) viruses that are circulating in animals," it added.
Avian influenza A(H3N8) viruses have been detected in dogs, horses, pigs, donkeys and most recently seals, but the UN agency said the virus does not appear to have the ability to jump easily from person to person, meaning the risk of an epidemic is low. But it warned that global surveillance was needed to detect "changes associated with circulating influenza viruses."
Many countries have been on a lookout for H5N1 bird flu, which spread globally in 2008 and has been making occasional spillovers to mammals.