http://sg.news.yahoo.com/bird-flu-strain-may-capable-spreading-human-human-113448702.html
By Lavinia Mo
HONG KONG (Reuters) - The new H7N9 bird flu virus can be
transmitted between mammals not only via direct contact but also in
airborne droplets, and may be capable of spreading from person to
person, Chinese and American researchers have found.
A study published in the journal Science and presented at a
briefing in Hong Kong on Friday found that three ferrets - an
animal often used for research on flu - that were in the same cage
as ferrets infected with H7N9 had contracted the disease.
One of three ferrets kept in separate cages nearby also became
infected, through airborne exposure.
The World Health Organization (WHO) has previously said it has no
evidence of "sustained human to human transmission" of the virus,
which has killed 36 people in China.
"The findings suggest that the possibility of this virus evolving
further to form the basis of a future pandemic threat cannot be
excluded," said the research team, led by bird flu expert and
microbiologist Yi Guan.
The virus can also infect pigs, but could not be transmitted from
pig to pig or from pigs to other animals, the study showed,
although the team urged authorities to maintain surveillance to
check whether the virus was mutating.
The WHO said the findings were useful but warned that people "have
to be very careful about what's going on the ground".
"Studies like that are really helpful for increasing general
knowledge and it's really helpful to know that, under lab
conditions, this thing could transfer from person to person," WHO
chief spokesman Gregory Hartl told Reuters.
"We've already seen maybe a few limited instances of human to human
transmission within close family range, within close contacts, so
this is another piece of the puzzle," he said.
The findings come just days after the WHO said the H7N9 virus
appeared to have been brought under control in China thanks to
restrictions at bird markets.
H7N9 has relatively mild clinical signs in ferrets, according to
the study. All the animals infected with the virus in the
experiments presented symptoms for no more than seven days and all
recovered from the disease.
The researchers said that all cases where humans had died or become
extremely ill had involved additional factors.
The team also found that some infected animals did not develop
fever or other clinical signs, suggesting that asymptomatic
infections among humans may also be possible.
"The potential public health implication of this ... is that a
person infected by H7N9 avian influenza virus who does not show
symptoms could nevertheless spread the virus to others," the
researchers wrote in their study.
United Nations experts said this week the bird flu outbreak in
China had caused some $6.5 billion in losses to the economy.
The H7N9 virus is known to have infected 131 people in mainland
China and one in Taiwan since February, but no new cases have been
detected since early May.
(Additional reporting by Kate Kelland in London, Sui-Lee Wee in
Beijing and Tom Miles in Geneva; Editing by Ron Popeski and Sonya
Hepinstall)
