28 April 2013
AFP - There is no evidence that the deadly H7N9 bird flu has
yet spread between humans in China but health authorities must be ready
for the virus to mutate at any time, a top US virologist has warned.
Anthony Fauci, the head of the National Institute of Allergy and
Infectious Diseases (NIAID), said officials in China had studied more
than 1,000 close contacts of confirmed cases and not found any evidence
of human-to-human transmission.
"That is powerful evidence because if you had a thousand contacts
with someone with the flu you would be pretty sure some of them would
have been infected," Fauci said in an interview with AFP.
Nevertheless, Fauci cautioned that authorities needed to be ready for
the possibility of the virus mutating and spreading between humans.
"It's unpredictable as are all the influenza. One of the things we
need to be concerned about is this might gain the capability of going
human-to-human which up to this point has not happened and is somewhat
encouraging news," Fauci said.
"But we still need to be very prepared for the eventuality of that happening."
Researchers are already developing a diagnostic test to identify
H7N9, along with a vaccine, with clinical trials due in July or August.
"Work is under way on making a diagnostic test to be able to pick it up quickly," Fauci said.
"We have already started on an early development of a vaccine as we
did with H5N1 years ago... Hopefully, we will never have to use it."
More than 110 people in mainland China have been confirmed to be
infected with H7N9, with 23 deaths, since Beijing announced on March 31
that the virus had been found in humans.
Most of the cases have been located in eastern China, although Taiwan
has reported one case. Another case has been found in southern China,
while Chinese officials confirmed a further outbreak in the central
province of Hunan.
Chinese authorities have identified poultry as the source of the
virus and have confirmed that patients became sick from contact with
infected live fowl.
A visiting team from the World Health Organization, which wrapped up a
week-long visit to China on Wednesday, said there had been no
human-to-human transmission but warned H7N9 was "one of the most lethal"
influenza viruses ever seen.
Fauci praised Beijing for its handling of the current crisis,
contrasting it to the response of the outbreak of severe acute
respiratory syndrome in 2002-2003, when China stood accused of
covering-up the scale of the crisis.
"It was not the case with SARS in 2003 but the transparency has been
excellent," Fauci said. "I am quite satisfied with the Chinese
Fauci likened the current H7N9 strain of bird flu "in some respects" to the H5N1 bird flu strain of several years ago.
"The similarities are that it is fundamentally a chicken or bird flu
that jumps from chicken to humans and is quite severe when it infects
humans," he said.
However, Fauci added: "The difference between H7N9 and H5N1, is that
H5N1 kills chickens very rapidly so it is easy to identify where the
infected flocks of chickens are. H7N9 doesn't make the chicken sick, so
it has been difficult to pinpoint where the infected chickens are."
There have been 566 confirmed cases of the H5N1 strain of bird flu,
which killed 332 people in the world -- a mortality rate of 58 percent,
compared to 20 percent for the H7N9 bird flu strain.
The H1N1 "swine flu" pandemic o 2009, which appeared in Mexico at the
same time of year as the H7N9, eventually infected 60 million people
throughout the world and killed more than 12,000.
The 1918 Spanish flu, which has been called one of the deadliest
plagues in human history, had a mortality rate of only two percent.