- [1] Date: Thu, 26 Aug 2004
- From: ProMED-mail Source:
- CIDRAP News, 24 Aug 2004 [edited]
-
- http://www.cidrap.umn.edu/cidrap/content/hot/
avianflu/news/aug242004avflu.html
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- China Confirms Avian Influenza H5N1 Now In Pigs
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- Chinese health officials confirmed yesterday that H5N1
avian influenza had been found in pigs there in 2003 but says no such findings
have occurred in 2004. They also stated that the occurrence had been made
public earlier in the year, although the UN Food and Agriculture Organization
(FAO) says there has been no official report of the disease in pigs.
-
- The Chinese ministry of agriculture in a press release
stated that, spurred by the widespread outbreaks of avian flu in Asia earlier
in 2004, they have tested 1.1 million samples from poultry and some samples
from pigs and that no H5N1 has been found in pigs, Chinese news agency
Xinhau reported.
-
- The agency said also that the 2003 finding of the virus
in pigs had been made public earlier in 2004. It turns out that an article
reporting the findings appeared in the January issue of the Chinese Journal
of Preventive Veterinary Science and another in the May issue. The latter
reported that the virus was found in April 2003 in pigs at 4 locations
near the east coast of China. The articles are in Chinese; translation
for FAO and the World Health Organization (WHO) is under way. [See below,
postings on Avian influenza, porcine, H5N1 - China. - Mod.AS]
-
- Confusion began when a prominent Chinese avian influenza
expert, Chen Hualan, an author of the 2 studies, said in a presentation
at an international meeting late last week that the H5N1 virus had been
found in pigs in China in both 2003 and 2004, to the surprise of WHO and
FAO officials, who were not aware of this. A New York Times story says
a press official of the Chinese health ministry was likewise surprised
when told later of the expert's comments and that he said his office had
no information on the subject. It is unclear whether Chen's remarks had
been officially authorized.
-
- The state-run Beijing Times ran a story today saying
that Chen, after several days of silence, called the amount of avian flu
virus in the pigs "extremely small," with the probability of
isolating H5N1 from the animals "less than one in 1000," according
to an AFP story. The story also stated that an unnamed spokesperson for
the ministry of agriculture said "some experts' remarks" were
at odds with the government's view of events.
-
- FAO official Juan Lubroth said several details about
the cases in pigs, including whether the animals in which H5N1 was found
became sick, are crucial, the New York Times story says. If the pigs did
not become ill, he explained, they would be harder to detect and quarantine
or destroy, although this might also indicate that the virus had lost some
of its potency. The WHO, in a statement on its Web site, points out the
importance of comparing the H5N1 isolated from pigs with the strain isolated
from poultry to determine whether the virus was passed directly from poultry
to pigs. Shigeru Omi, WHO regional director for the Western Pacific, told
AFP that "We have asked [Chinese officials] for information, but so
far there have been no additional details. Overall the Chinese government
has been cooperative and I hope they will remain so."
-
- In other developments, the state-run Thai News Agency
reported the August [2004] death of a dozen pigs in a northern province,
according to a Xinhau story. The animals reportedly had symptoms of coughing,
breathing difficulty, and swelling eyes. Chickens on the same farm had
died earlier of avian flu, the story says. This report has not been confirmed.
[More details will be appreciated. - Mod.AS]
-
- [Byline: Marty Heiberg, Managing Editor, Center for Infectious
Disease Research & Policy Academic Health Center -- University of Minnesota]
-
- ****** [2] Date: Thu, 26 Aug 2004
- From: ProMED-mail promed@promedmail.org
- Source: WHO update of 25 Aug 2004, via F.I.C., 26 Aug
2004 [edited] http://www.flu.org.cn/newsparticular.asp?link_id=59
-
-
- Avian Influenza Update: Implications of H5N1 Infections
in Pigs in China
-
- -------------------------------------------------
-
- Considering the widespread nature of the current H5N1
outbreak in Asia and the capability of influenza viruses to jump the species
barrier, it is inevitable that H5N1 virus will be detected in some pigs.
Pigs can be infected with both avian and human influenza A viruses -- for
instance, human influenza H3N2 viruses have been detected in pigs in Asia,
Europe and Africa.
-
- Some of these human and avian influenza viruses might
become adapted to pigs and then begin circulating in pig populations. The
co-circulation of avian, human, and pig viruses in pigs is of significant
concern because of the potential for a genetic exchange, or "reassortment,"
of material between these viruses. Such an occurrence has the potential
to produce a new pandemic influenza strain.
-
- Last week, a researcher at China's Harbin Veterinary
Research Institute announced that pigs from farms in parts of China had
been infected with the H5N1 strain of avian influenza. China's Ministry
of Agriculture has since confirmed the researcher's findings. What is unclear
from the few studies that have been conducted is whether the H5N1 virus
has already become established in pig populations in China.
-
- Because the findings remain preliminary and are not necessarily
indicative of widespread infection among pigs, assessing the consequences
of this information for public health is difficult. Providing a detailed
risk assessment of the current situation requires an understanding of the
main factors influencing the potential for the emergence of a pandemic
influenza strain: the prevalence of H5N1 and human H3N2 virus in pigs in
Asia, and the likelihood of a reassorted virus and its possible pathogenicity.
-
- The role of pigs in genetic reassortment is not fully
understood. While there has been no known natural occurrence of reassortment
of influenza viruses in pigs that resulted in a new pandemic strain, the
probability of this occurrence is not negligible.
-
- The chances for genetic reassortment depends upon both
the duration of H5N1 circulation in pigs as well as the simultaneous presence
of human and pig influenza A viruses (such as H3N2 or H1N1). As long as
human and avian influenza viruses are co-circulating -- whether in humans
or in pigs -- the possibility of an exchange of genetic material exists.
-
- To better understand the implications of the findings
in China, WHO is encouraging that additional studies be conducted on H5N1
and other influenza A viruses in pigs in China, as well as in other countries
which have experienced H5N1 avian influenza outbreaks. In addition, laboratory
experiments would be required to shed some light on the probability for
virus reassortment, the possible pathogenicity of a reassorted virus, and
the chance that pigs will act as a pathway for the emergence of a potential
pandemic strain. These results will help national and international public
health authorities not only to assess the role pigs and humans play in
the emergence of a new influenza pandemic virus from H5N1, but also to
structure the necessary public health interventions.
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- Patricia A. Doyle, PhD Please visit my "Emerging
Diseases" message board at: http://www.clickitnews.com/ubbthreads/postlist.php?
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