HO CHI MINH CITY, Vietnam, February 28, 2005 (ENS): The avian
influenza virus (H5N1) circulating among poultry, ducks
and wildlife in Southeast Asia continues to pose a serious
threat to human and animal health, veterinary officers
from 28 countries said Friday. The health experts concluded
a three day meeting by warning that bird flu poses the
“gravest possible danger” of becoming a
global pandemic, and hundreds of millions of dollars
are needed to control the threat.
Health officials suspect that the viral strain circulating
in birds could mutate into another virus transmissible
from human to human. If that happens, they say, a global
flu pandemic could develop with the potential to cause
tens of millions of deaths.
Over 140 delegates from 28 countries and regions as
well as international organizations attended the meeting
to find ways of halting the disease.
Convened by the UN Food and Agriculture Organization
(FAO) and the World Organization for Animal Health (OIE),
the delegates agreed that progress has been made in
the early detection of and rapid response to the disease,
but they say that prevention and control are now at
a critical time and stronger joint efforts are needed
in the battle.
The animal health experts implored the international
community to provide greater support to affected nations
in their attempts to track the disease and develop better
methods for containing it.
They estimated that $100 million in assistance is needed
to upgrade veterinary services and laboratories to improve
virus detection and its ultimate eradication, according
to a final FAO report on the meeting.
Several hundred million dollars would be required to
finance the restocking of infected poultry flocks and
to restructure the whole sector, they suggested.
Since the epidemic of highly pathogenic avian influenza
caused by H5N1 first emerged in North Korea in mid-December
2003, it has spread to eight Asian countries, and hundreds
of millions of birds have been culled at great cost
to poultry producers in the region.
The disease has crossed the species barrier with at
least 55 human cases reported, according to the World
Health Organization. Of the 55 cases reported, 42 people
have died in Vietnam, Thailand and Cambodia.
In January 2004 laboratory tests confirmed the presence
of H5N1 avian influenza virus in human cases of severe
respiratory disease in the northern part of Vietnam.
As the conference concluded Friday, news came that
a 21 year old man from Vietnam's northern Thai Binh
province was diagnosed with the avian influenza (H5N1)
virus infection, and his younger sister also is suspected
of having the virus, reported the local newspaper "Youth."
The young man is the third case of bird flu infection
diagnosed in Thai Binh this year. Vietnam has experienced
three outbreaks of bird flu in humans in the past 18
months, and 32 people have died.
The bird flu virus does not respect borders and needs
a strong regional response, the veterinary officers
said. Regional cooperation networks recently established
by the FAO should be extended, they said, but without
proper funding, these networks will cease their activities
within the next six months.
Delegates called upon the global community to help
with the financing of these costly but essential efforts.
The conference delegates recognized the link between
farming systems and the spread of the virus, especially
the proximity between chickens and ducks in many backyard
households that appears to be contributing to the circulation
of the disease.
In addition, the movement and marketing of live animals,
not controlled by veterinarians, are a major cause for
spreading the disease, they said.
There are between 25 and 40 million village backyard
poultry farmers in Cambodia, Indonesia, Laos, Thailand
and Vietnam, who keep poultry for income and food security.
To protect humans by minimizing the risk of virus transmission
between species, delegates recommended that these farmers
segregate chickens, ducks, and other animals such as
pigs from one another. They said contact between these
animals and humans must be kept to a minimum.
The meeting agreed that vaccines can be a strong weapon
in the fight against the disease in poultry, and that
the possibility of vaccinating ducks should be explored.
Still, delegates acknowledged the need to further study
conditions in which vaccines can be delivered with minimum
risk to human health.
The U.S. government is preparing to test an avian flu
vaccine and stockpiling both vaccine and antiviral drugs
as the threat grows that the deadly strain of bird flu
will begin spreading from Asia.
Two million doses of vaccine are being stored in bulk
form for possible emergency use and to test whether
it maintains its potency, officials said Thursday
The new vaccine was prepared in two different concentrations
of 4,000 doses each, and it is nearly ready to be shipped
to the National Institute for Allergy and Infectious
Diseases (NIAID) for clinical trials, said Len Lavenda,
a spokesman for the vaccine manufacturer Sanofi Pasteur.
NIAID Director Dr Anthony Fauci said the vaccine will
be tested at centers in Rochester, New York, St Louis
and in Maryland and Texas to ensure its safety and to
determine the proper dosage for the elderly, children
and healthy young people.
Dr. Julie Gerberding, director of the U.S. Centers
for Disease Control and Prevention, told reporters on
February 22 during a talk at the National Press Club
in Washington, DC, that “it is a worrisome situation,”
though she also said the United States “is not
immediately on the brink of an avian flu epidemic.”
But the disease may already be more widespread in humans
than has previously been recognized. An article published
in the journal "Nature" on Thursday indicates
that some Vietnamese doctors have been incorrectly clearing
patients of the H5N1 virus when they were actually infected.
Reanalysis of samples from Vietnamese patients with
flu-like symptoms at the National Institute of Infectious
Diseases in Tokyo has shown that some people originally
declared free of avian influenza did carry the H5N1
The article by David Cyranoski, entitled "Tests
in Tokyo reveal flaws in Viet Nam's bird flu surveillance,"
could prompt experts to re-evaluate the severity of
the avian flu in humans. To date, the death rate for
infected patients has been high - 10 of the 11 cases
identified in Vietnam since December 2004 have died.
But if more cases exist although unidentified, the mortality
rate could be lower, but the disease could be recognized
as more prevalent.
Avian influenza is an infectious disease of birds caused
by type A strains of the influenza virus such as H5N1.
The disease, which was first identified in Italy more
than 100 years ago, occurs worldwide.
Migratory waterfowl, especially wild ducks, are the
natural reservoir of avian influenza viruses, and these
birds are also the most resistant to infection, according
to the World Health Organization (WHO). Domestic poultry,
including chickens and turkeys, are particularly susceptible
to epidemics of rapidly fatal influenza.
Direct or indirect contact of domestic flocks with
wild migratory waterfowl has been implicated as a frequent
cause of epidemics. Live bird markets have also played
a role in the spread of epidemics.
Influenza A viruses, such as H5N1 virus, are particularly
dangerous, health experts say, because they can swap,
or reassort, genetic materials and merge. This reassortment
process, known as antigenic shift, results in a new
subtype different from both parent viruses.
"As populations will have no immunity to the new
subtype, and as no existing vaccines can confer protection,
antigenic shift has historically resulted in highly
lethal pandemics," WHO says.
For this to happen, the novel subtype needs to have
genes from human influenza viruses that make it readily
transmissible from person to person for a sustainable
Conditions favorable for the emergence of antigenic
shift are thought to involve humans living close to
domestic poultry and pigs. Because pigs are susceptible
to infection with both avian and mammalian viruses,
including human strains, they can serve as what the
WHO calls a “mixing vessel" for the "scrambling
of genetic material from human and avian viruses,"
resulting in the emergence of a new viral subtype.
But, WHO says, evidence is mounting that, for at least
some of the 15 avian influenza virus subtypes circulating
in bird populations, "humans themselves can serve
as the mixing vessel."
Copyright Environment News Service (ENS) 2005. All