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AVIAN INFLUENZA - ASIA (20): JAPAN (IBARAKI), POULTRY, H5N2
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Date: Mon 5 Sep 2005
From: ProMED-mail <promed@promedmail.org>
Source: The Asahi Shimbun (English edition), 5 Sep 2005 [edited]
<http://www.asahi.com/english/Herald-asahi/TKY200509050206.html>
1.5 million chickens being culled due to bird-flu outbreak
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The agriculture ministry has announced plans to cull about 1.5 million
chickens following an outbreak of avian flu at poultry farms in Ibaraki and
Saitama prefectures. Officials said it was a relatively weak strain of bird
flu and that 504 000 chickens had already been destroyed. An additional
1.024 million birds are to be killed to prevent the disease from spreading.
The area of infection has 30 farms with 4.14 million hens.
Officials of the Ministry of Agriculture, Forestry and Fisheries said there
is a strong possibility that the infection was caused by the use of an
unauthorized and defective vaccine that contained an active virus.
Authorized vaccines contain modified, killed or avirulent viruses or
bacteria. [The last remark is related to vaccines in general, not
exclusively to the AI (viral) vaccine. - Mod.AS]
Officials are scrambling to pinpoint the source of the outbreak, because
even a weak strain of avian flu virus can quickly become highly virulent.
The diluted [attenuated?] strain of avian flu was 1st detected on 26 Jun
2005 at a chicken farm in Mitsukaido, Ibaraki Prefecture. Chickens at a
total of 30 farms in the prefecture and neighboring Saitama Prefecture have
since been confirmed to be infected. All of the chickens at the infected
farms were being raised for egg-laying.
In Ibaraki Prefecture, chickens at farms hit by avian flu account for a
third of all hens in the prefecture. Amid signs that the area of infection
was spreading, the agriculture ministry, on 22 Aug 2005, changed its policy
of destroying every chicken at the farms in question. Of the roughly 1700
poultry farms around Japan, avian flu has been detected at 29 in Ibaraki
Prefecture and one at Saitama Prefecture. For that reason, the ministry
concluded that nationwide infection is highly unlikely, officials said. The
ministry, meanwhile, speculated on Friday [2 Sep 2005] that some farm
operators had used an unauthorized vaccine to quell infection, they added.
Ministry officials suspect that some viruses may have survived a viral
inactivation treatment for vaccine production. As a result, any virus that
survived the treatment could have been active and transmitted from bird to
bird, the officials said. The DNA sequence of the flu virus was almost
identical to those that were confirmed in Mexico, Guatemala and El Salvador
between 1995 and 2002, they added. Even so, ministry officials said it was
highly unlikely that avian flu was carried by migratory birds. Aside from
the huge distance between Central America and Japan, they noted that no
trace of birds infected with the virus had been imported to Japan.
The Japan Poultry Association, meanwhile, posted an announcement on its
website disavowing any knowledge of the use of illegal vaccines. To prevent
a massive outbreak of bird flu in Japan, the farm ministry maintains a
stockpile of vaccine for about 7 million chickens. Ordinary farmers do not
have access to the vaccine, which so far has not been used.
--
ProMED-mail
<promed@promedmail.org>
[Although no details are given, the suspicion of an unauthorized vaccine
being at the background of the event might be attributed to epidemiological
investigations. If large numbers of birds, in different farms (probably
administratively inter-related), demonstrate a similar level of antibodies
against a common antigen, vaccination might be the etiological factor.
Further investigations might be expected.
In August 2004, the Japanese Ministry of Agriculture discovered that an
outbreak of classical swine fever in Kagoshima Prefecture had been caused
by an unauthorized vaccine. - Mod.AS]
[see also:
Avian influenza - Asia (19): Japan (Ibaraki), poul... 20050903.2604
Avian influenza - Asia (14): Japan (Ibaraki), poultry, H5N2 20050827.2532
Avian influenza - Asia (03): Japan (Saitama), poul... 20050818.2418
Avian influenza - Asia (08): Japan (Ibaraki), poultry 20050822.2470
Avian influenza - Eastern Asia (58): Japan, H5N2 20050626.1799
Avian influenza - Eastern Asia (60): Japan, H5N2 20050630.1845
Avian influenza - Eastern Asia (61): Japan, H5N2 20050701.1850
Avian influenza - Eastern Asia (62): Japan, H5N2 (OIE) 20050702.1870
Avian influenza - Eastern Asia (76): Japan 20050727.2171
Avian influenza - Eastern Asia (78): Japan, susp. 20050729.2213
Avian influenza - Eastern Asia (79): Japan, H5N2 (OIE) 20050730.2223
2004
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Swine fever, classical - Japan (06): susp. 20040804.2131]
.............arn/msp/sh
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