A new report published in The Lancet details the world’s first confirmed case of human infection with a new avian influenza virus that has genetically evolved from the H10N8 virus. A 73-year-old woman from Nanchang City in China died 9 days after the onset of illness from the infection.
On November 30th, 2013, the woman visited a hospital with symptoms of fever and severe pneumonia. Although she was treated with antibiotics and antiviral medication, she quickly deteriorated and developed multiple organ failure before passing away.
After collecting tracheal swab samples from the woman, clinicians discovered that she died from an avian virus that is a new strain of the H10N8 virus, which researchers have called JX346.
“The microbe culture and deep sequencing data showed that the avian influenza A H10N8 virus was overwhelmingly dominant in tracheal aspirate specimens, indicating that the JX346 virus infection was associated with the illness and death of the patient,” the study authors say.
The H10N8 virus had previously been isolated from a water sample taken at Dongting Lake in Hunan Province, China, in 2007 and had also been identified at a live poultry market in the Guangdong province of China in 2010. However, no human infection with this virus has ever been reported.
On carrying out genome sequencing on the samples of the new strain, investigators found that all the genes of the JX346 virus were of avian origin and that six internal genes came from avian H9N2 viruses that are already circulating poultry in China.
Researchers found that 4 days before infection, the woman had visited a live poultry market. This indicates there is a 4-day incubation time from infection – similar to that of other bird flu infections.
However, on collecting samples from the live poultry market that the woman visited, scientists found no H10N8 virus present, meaning the infection source cannot be identified.
The study authors say that the JX346 strain is distinct from previously reported H10N8 viruses. They believed it has evolved to adopt enhanced genetic characteristics that may lead to more effective replication in humans.
“[The results suggested that] JX346 might originate from multiple reassortments between different avian influenza viruses,” explains Dr. Yuelong Shu, from the Chinese Center for Disease Control and Prevention in Beijing and co-author of the report.
“The H10 and H8 gene segments might have derived from different wild bird influenza viruses reassorted to give rise to a hypothetical H10N8 virus in wild birds, which infected poultry and then reassorted with H9N2 viruses in poultry to give rise to the novel reassortant JX346 (H10N8) virus.”
Furthermore, the researchers say the JX346 virus has a mutation in the PB2 gene, which scientists believe is linked to increased infection and adaption in mammals. This means the virus has the potential to become more infectious in humans.
Dr. Mingbin Liu, of the Nanchang City Center for Disease Control and Prevention in China, notes that a second case of H10N8 infection was found in Jiangxi Province in China on January 26th, 2014.
“This is of great concern because it reveals that the H10N8 virus has continued to circulate and may cause more human infections in future,” he adds.
The researchers conclude:
“A H5N1 virus infection in Hong Kong in 1997 preceded the next 17 cases by 6 months, so more human cases of H10N8 infection might occur in the future. The pandemic potential of this novel virus should not be underestimated.”
Last year, Medical News Today reported on the world’s first case of a wild influenza A H6N1 virus in a 20-year-old Taiwanese woman.