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
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
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
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
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
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 virus.
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
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 period.
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 Rights Reserved.