ANGKOK, Saturday, Jan. 24 — Human cases of avian
influenza, contracted from birds, have turned up in a second Asian
country, Thailand, showing the virus has spread in recent weeks. The
announcement, made by the Thai government on Friday, has deepened fears of
a global epidemic if the virus combines with another that can be
transmitted from person to person.
The Thai government's chief spokesman said the outbreak had been
concealed for "a few weeks" to avoid panic. The concealment also allowed
Thailand's politically powerful chicken industry to keep up exports until
word leaked late this week, although officials said they had ensured none
of the exported meat was infected.
Speaking of the cases in Thailand, Dr. Klaus Stöhr, an influenza expert
at the World Health Organization in Geneva, said, "This changes the
ballgame by posing an increased level of risk" to people.
Thailand reported that two boys from different provinces had become
infected with the bird flu, and six more people are suspected of having
it. Vietnam has already reported five confirmed fatal cases in people near
Hanoi, and on Saturday reported two more confirmed cases in Ho Chi Minh
City, while seven additional suspected cases are being tested in the
country. Chickens from South Korea and Japan, to Vietnam and Thailand,
have been dying from the same disease.
So far, the human cases have resulted from contact with live chickens
or their waste. But the World Health Organization, a United Nations
agency, has warned repeatedly that if someone becomes infected with the
bird flu and the human flu at the same time, the viruses could swap
genetic material, creating a new strain that could spread quickly among
people. Nobody knows how long this might take, if it happens at all, but
work has begun on a vaccine in case one is needed.
The three largest influenza epidemics of the 20th century are believed
to have started in birds. The A(H5N1) strain now killing chickens across
East Asia and infecting humans in Southeast Asia appears to be especially
lethal.
The W.H.O. said it did not know why children account for eight of the
nine avian influenza cases in Vietnam and Thailand. It may be that adult
cases have been attributed to another respiratory infection. Still, Dr.
Stöhr said, the point "adds to our concerns" because the influenza
pandemic of 1918-19 affected millions of people in the prime of life.
The Thai government has vehemently denied for the last week that there
was any avian influenza in Thailand, insisting that it was bird cholera.
But Jakrapob Penkair, the government's chief spokesman, said in a
telephone interview on Friday night that the government had known for a
few weeks that chickens were dying of avian influenza. "It was kept from
the public, but full-scale operations have been under way" to control the
problem, he said.
The Thai operations, conducted jointly with the country's biggest
agricultural businesses, involved killing chickens at farms where there
were infections or halting the sale of these chickens, while quietly
testing for bird flu all Thai chicken going to the country's main export
markets, Mr. Penkair said. Japan buys half of Thailand's chicken exports
and the European Union buys another third.
On Thursday, Japan temporarily suspended the import of Thai chickens,
and the European Union did so on Friday. The W.H.O. has said that while
the feces, saliva and breath of the chickens may contain the virus, no
evidence exists that the meat can cause illness.
Countries that have banned poultry from the affected nations are trying
to prevent introduction of the virus to their own flocks. "It's probably a
good idea, if you want to protect your own poultry production, that you
put in place some effort to try to keep live birds out," said Dr. Jorgen
Schlundt, who directs W.H.O.'s food safety program.
In the United States, sporadic outbreaks of avian influenza have
occurred among birds, and flocks are monitored for the disease, a
spokesman for the Department of Agriculture said. He said there was little
risk of avian flu entering through infected poultry because the United
States allows imports of poultry and poultry products only from countries
free of another infection, Newcastle disease. They number fewer than 10,
and none are in Asia.
The A(H5N1) virus was first documented to have jumped to people in
1997, when sick chickens infected 18 people in Hong Kong, including
previously healthy adults, killing 6. All 1.5 million chickens there were
slaughtered within three days, a step some influenza experts have credited
as preventing a global epidemic.
Two residents fell sick with the disease after visiting their nearby
hometown in the main part of China last year, and one of them died. Again,
flocks were destroyed.
Cambodia confirmed Friday that bird flu had been killing chickens
there. Laos said earlier this week that it was investigating chicken
deaths but believed them to be bird cholera. Agence France-Presse reported
from the Indonesian island of Bali on Friday that a provincial official
had acknowledged the death of thousands of chickens, but blamed it on the
Newcastle virus.
There have been unconfirmed reports of chicken deaths in Myanmar as
well; Mr. Penkair said that infected chickens had been found in "three or
four" western provinces of Thailand, toward the Myanmar border.
China has continued to deny, most recently on Thursday, that it has any
cases of bird flu. But Hong Kong officials said on Wednesday that they had
found a dead peregrine falcon near the border with the rest of China that
was infected with the disease.
Dr. Nancy J. Cox, a top influenza virologist at the Centers for Disease
Control and Prevention in Atlanta, said health officials hoped that the
spread that had resulted from delays in reporting bird flu cases would
serve as a lesson about the risks of the disease to international
health.
C.D.C. has received A(H5N1) viruses isolated from a chicken in South
Korea and from people and poultry in Vietnam, Dr. Cox said. She said the
agency was working with the W.H.O. to modify the virus so it could be used
to develop a human vaccine in case it was needed.
Japan has followed Hong Kong's example, abiding by international
guidelines for the disposal of infected fowl. Workers in biological hazard
suits gathered, killed and wrapped in plastic all fowl in the area where
the infection occurred, then buried them in special pits using bulldozers
with special air-filtration equipment.
But while industrialized countries have such equipment, poorer
countries, like Vietnam, do not. Instead, workers with little or no
protection have been wading into large flocks of chickens to kill them.
The W.H.O. estimates that thousands of workers have been exposed as a
result.
Vietnamese officials have also acknowledged that farmers sold as food
nearly 800,000 chickens that were supposed to have been destroyed; the
Vietnamese government has offered as little as 10 cents on the dollar to
compensate farmers who destroy their chickens. Foreign governments have
not offered to help the impoverished country pay more.
Keith Bradsher reported from Bangkok for this article and Lawrence
K. Altman from New York.
