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* Virus could mutate -CDC director
* If virus mutates, could cause “severe pandemic”
* H7N9 began infecting people in February
By Julie Steenhuysen
NEW YORK, May 6 (Reuters) – The head of the U.S. Centers for
Disease Control and Prevention says the current strain of bird
flu that is causing illness and deaths in China cannot spark a
pandemic in its current form – but he added that there is no
guarantee it will not mutate and cause a serious pandemic.
In an exclusive interview at the Reuters Health Summit in
New York, Dr. Thomas Frieden, director of the CDC, said more
than 2,000 people have been in contact with infected
individuals, and only a handful have become ill.
Virtually all of the rest have had direct contact with
poultry, the identified cause of the virus.
“This particular virus is not going to cause a pandemic
because it doesn’t spread person-to-person,” Frieden said.
“But all it takes is a bit of mutation for it be able to go
person-to-person.”
“I cannot say with certainty whether that will happen
tomorrow, within 10 years or never.”
The new strain of bird flu known as H7N9, which began
infecting people in February, has so far sickened at least 127
people and killed 27. According to the latest
CDC estimates, the flu kills about 20 percent of the people it
infects.
The United States has been working closely with Chinese
health officials, and has recently distributed test kits to
detect this new strain of flu, which has never before appeared
in humans.
Tests by Chinese health officials have found the virus in
chickens, ducks and pigeons, but Frieden said it is not yet
clear how the virus spreads in birds.
New strains of flu present a threat because if they do
become easily transmissible, they might quickly spread around
the globe, attacking individuals who have no natural defense
against the virus.
The CDC has activated its Emergency Operations Center to
monitor the disease and currently has 193 staff working on H7N9.
“We’ve got a team working in China, Laos, Cambodia and Vietnam,”
he said.
Frieden said there are several factors that make this
particular virus especially worrisome.
An analysis of the genetic code of the virus shows that it
has receptors that bind to the lower respiratory tract of
people, much like the more familiar bird flu strain known as
H5N1. “That is why it’s causing severe disease,” Frieden said.
But it also has receptors that bind to the upper respiratory
tract of people, which may explain why it is more transmissible
from birds to people than H5 appears to be, he said.
And unlike H5N1, which caused severe disease in poultry,
this new virus does not, which may make it more difficult to
control because researchers will not be able to cull poultry
flocks.
Frieden said even with H5, it took 18 months from the
emergence of the virus until the 100th case. By comparison, it
took only about one month from the emergence of H7 until the
100th case.
“If you look at the geographic spread of H5, within a couple
of years it was all over Asia, into Africa, into the Middle
East,” he said.
Frieden said he cannot predict what the spread of H7 will be
in birds, though he said he is concerned it may be quite wide.
“If there is evolution in the virus, it could go
person-to-person, and that could cause severe pandemic.”
In the United States, the CDC has developed and distributed
H7N9 test kits, given to states and to several countries.
Frieden said the agency is working on flu vaccines for the
virus and clinical trials could begin in the summer.
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(Editing by Matthew Lewis)
