"We need to take a close look at the viruses to see if we are dealing with a continuation of the major outbreaks earlier this year or whether this is a new Highly Pathogenic Avian Influenza A (H5N1) virus," said Dr Shigeru Omi, regional director of WHO's Western Pacific Regional Office. "The answer to that question will help guide our response."
In the past two weeks, outbreaks of avian influenza have been confirmed in
poultry in China, Thailand and Vietnam. "If we can compare the viruses with
each other and with those from the earlier outbreaks, we will have a much
better picture of what is going on," said Omi. So far, tens of thousands
of chickens and ducks have been slaughtered to halt the spread of the
infection. There are no confirmed human infections so far in these countries.
Omi said the affected countries had responded quickly to the threat,
but he warned that there was still a significant risk to public health.
"Human contact with infected poultry could result in the virus jumping to
humans," he said. "This could produce a new influenza virus against which
there is no immunity. Obviously, the potential for a flu pandemic is still
WHO is urging affected countries and those with previous outbreaks to
carry out urgent risk-assessment activities, including enhanced surveillance
in animals and humans, and strain analysis. WHO is working closely on this
with agriculture authorities and other international organizations such as
Food and Agriculture Organization and theWorld Organization for Animal
Health). It also liaising with national health authorities to strengthen
Recent reports in professional journals that the virus may be more
entrenched across the region than previously thought and also more pathogenic have heightened concern about the risk to human health. "There is no need for public anxiety, but it is vital that the countries affected share what they know with the international community," said Omi.
China: The Ministry of Agriculture informed WHO's Beijing office on July 6, 2004 of an outbreak of avian influenza at a farm in Anhui Province, west of
Shanghai. The Ministry said the problem had probably started on 24 June and
had been identified four days later. Tests of samples carried out at the
National Avian Influenza Reference Laboratory in Harbin showed the virus to be H5N1. More than 8,000 chickens died or were slaughtered, and work promptly began on culling all chickens within a radius of 3 km from the affected farm. A local official was later reported as saying that a further 120,000 birds
within an 8-km radius were being vaccinated and that authorities were limiting
the movement of people living in the area. The trade in live poultry was
suspended in all wet markets in the nearby city of Chaohu. No cases of human
infection were reported.
Thailand: Officials informed OIE of two outbreaks in provinces north of
Bangkok. In the first, reported on July 3, 2004, officials said 23,500 chickens had
been destroyed in the Pak Hai district of Ayutthaya Province. Four days later,
OIE was informed of an outbreak in the Muang district of neighbouring
Pathumthani Province, in which 730 chickens had been destroyed. In both cases, officials identified the virus as H5. The Public Health Ministry said it was
keeping a close watch on 34 workers on a farm in Ayutthaya for any possible
transmission of the virus. It said none of the workers had so far shown any
Vietnam: FAO was informed on June 29, 2004 of outbreaks of avian influenza on
three farms in Bac Lieu Province, in the Mekong Delta, south of Ho Chi Minh
City. On July 5, 2004, Dong Thap Province was also confirmed as having outbreaks. Unofficial sources also spoke of high prevalence of H5N1 infections in healthy poultry in southern provinces. So far, the virus has officially been
identified only as H5. The Vietnamese Ministry of Health's Steering Committee on SARS and Avian Influenza told WHO on July 8, 2004 that the Pasteur Institute in Ho Chi Minh City had carried out PCR testing on 80 samples taken from people having contact with poultry in the affected areas. All results were negative, including for four suspected human cases reported in the local media. In a July 2, 2004 statement, the Vietnamese Department of Animal Health
suggested that the outbreaks may have been caused by incomplete disinfection
of previously affected areas, accompanied by rapid restocking of farms.
Source: World Health Organization Western Pacific Region