By Kate Kelland
NEW DELHI (Reuters) Nov 14 - A woman in Taiwan has become the first person in the world with a confirmed case of a new strain of bird flu, adding to a growing list of examples of the potential threat from animal viruses that mutate to be able to infect people.
Scientists from Taiwan said the infection with the H6N1 bird flu strain appeared to be one isolated human case and probably posed little threat for the moment. But it illustrated how this virus, like others in the past, had been able to acquire genetic changes that allowed it to jump across species.
Another new strain of bird flu, H7N9, is continuing to infect and kill people in China after it first emerged in humans there earlier this year
Infectious diseases that pass from animals into humans have kept scientists on the alert for decades. Several major human epidemics, including HIV and the 2009/2010 H1N1 flu pandemic, began as zoonotic events.
The MERS coronavirus that has infected more than 100 people in the Middle East is thought to be harbored by camels, though researchers are still unsure of its ultimate origins or whether it will eventually become a disease easily transmitted among humans.
"This again underscores that there are so many viruses out there and we just don't really know which pose the greatest threats to us," Wendy Barclay, a flu virologist at Imperial College London, told Reuters when asked about the H6N1 case.
She called for more vigilance, surveillance and research into animal diseases with the potential to jump to humans.
In a study in Lancet Respiratory Medicine on Thursday, scientists said the H6N1 case was found in a 20-year-old woman from central Taiwan who went into hospital in May with flu-like symptoms and shortness of breath.
Initial tests on throat-swab samples taken from the patient indicated an unclassified subtype of a flu virus and further genetic analysis showed it was a new H6N1 bird flu virus very similar to chicken H6N1 viruses that have been circulating in Taiwan since 1972.
The woman responded to treatment with oseltamivir (Tamiflu) and has since fully recovered, they added.
Ho-Sheng Wu, who led the case study from the Centres for Disease Control in Taipei, said the important feature of the genetic analysis was that it showed the virus had a mutation in hemagglutinin that enables it to get into human cells and cause infection.
Further investigations into the patient found that she worked in a delicatessen, had not been abroad for three months prior to her infection, and had not been in close proximity to poultry or wild birds.
"The source of infection remains unknown," Ho-Sheng wrote in the study.
Barclay agreed that the woman's case appeared to be "for now an isolated case," adding: "It is possible that in these days of increased vigilance we are picking up the occasional zoonosis that we previously missed."
Ho-Sheng cautioned, however, that "as these viruses continue to evolve and accumulate changes, they increase the potential risk of human infection."
Lancet Respir Med 2013.
Reuters Health Information © 2013