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Published Date: 2002-11-01 23:50:00
Subject: PRO/AH> BSE - Japan (08): source
Archive Number: 20021101.5677

BSE - JAPAN (08): SOURCE
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A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: Fri, 01 Nov 2002
From: Suichi Hamamoto <shuichi_hamamoto@nm.maff.go.jp>

Investigation of the Bovine Spongiform Encephalopathy (BSE) Infection:
Agents and Routes
----------------------------------------------------------------------------------------
Outline of Second Interim Report
On 10 Sep 2001 Japan confirmed its first case of a dairy cow infected with
Bovine Spongiform Encephalopathy (BSE). Since then a second case was
confirmed on 21 Nov and a third case was confirmed on 2 Dec 2001. On 30 Nov
2001, the government released a report on the status of its investigation
on the infection agents and routes. Since then the investigation into these
3 cases has continued. This report, the Second Interim Report, provides in
update on the current status of these investigations.
I. Investigation of the Bovine Spongiform Encephalopathy (BSE) Infection
Agents and Routes for the first 3 cases
1. Status of Investigation
1.1 Investigation of farms where BSE was discovered
1.1.1 Records of infected cows
(1) The first infected cow was born in Hokkaido on 26 Mar 1996, was
transferred to Chiba Prefecture in April 1998 and was slaughtered on 6 Aug
2001 at the age of 5 years 4 months.
(2) The second infected cow was born in Hokkaido on 4 Apr 1996 and was
slaughtered on 19 Nov 2001 at the age of 5 years 7 months.
(3) The third infected cow was born in Gunma Prefecture on 26 Mar 1996 and
was slaughtered on 29 Nov 2001 at the age of 5 years 8 months.
1.1.2 Investigation of cows living on same farm as infected cows
(1) Among the cows that had lived on the same farm as one of the infected
cows, and had already died or been destroyed, there was no evidence of
symptoms to suggest that they were infected with BSE.
(2) Still existing cows that had lived on the same farm as one of the
infected cows were slaughtered and inspected for BSE. All of these cases
were negative.
1.1.3 Investigation of feed
(A) Meat-bone-meal (MBM)
(1) The materials used to make the formula feed and supplementary feed used
at the farms where the 3 BSE cases were discovered did not consist of any
MBM. However, 4 of the factories producing the formula feed for cows also
produced feed for pigs and poultry using MBM as one of the raw materials.
Because the same factories were used for producing the cow, pig, and
poultry feeds, and because it cannot be confirmed that the lines at these
factories were adequately cleaned when switching between the production of
the different feeds, the possibility that MBM could have become mixed with
the cow feed cannot be completely ruled out.
(2) A portion of MBM raw materials purchased by these 4 factories was made
from edible mutton and lamb food processing waste imported from Australia
and New Zealand, 2 countries that have never had an outbreak of BSE. The
remainder came from domestic slaughterhouses and meat processing factories.
(B) Imported Animal Fats
(1) The same feed factory provided milk replacer to the farms where the 3
infected cows were discovered. Animal fats (powdered fat) produced in the
Netherlands were used in this milk replacer.
(2) Animal fats imported up until June 1996 are considered to be one
possible common link between the 3 infection cases. The raw materials of
these animal fats contain back fats and other cow parts. Furthermore, these
animal fats can be used as foodstuff [for human consumption] and it is
likely that they are extremely pure, with the content of insoluble
impurities being 0.02 percent or less.
(3) However, these animal fats currently cannot be completely ruled out as
a possible source of infection for the 3 cows, as there still needs to be
confirmation as to whether or not the milk replacer in question was
provided to all 3 cows and whether or not it was possible that cow proteins
became mixed into the animal fats.
(C) Other Feed Materials
(1) Using the ELISA method, mammalian proteins were detected in
fishmeal provided by a total of 7 factories to be used as raw materials for
the formula feeds and supplementary feeds. It is believed that the detected
proteins were derived from screened foodstuff particles collected from
restaurants and other locations. The stocks of this food processing waste
used by the seven factories are now being examined as a precaution.
(2) The calcium phosphate used as a raw material in the formula feeds
and supplementary feeds came either from plants or minerals and so there
was no possibility of contamination of the MBM. [Dicalcium phosphate,
derived from animal bones, has been regarded elsewhere as one of the
products to be considered as a possible source of BSE infection. - Mod. AS].
(D) Feed Ingredients and Purchased Roughage
The factories and dealers providing feed ingredients and purchased roughage
do not handle any MBM and there is no possibility that these products could
have become contaminated with MBM during the production and shipping stages.
1.1.4 Other investigations
(1) The possibility is very remote that the infected cows somehow
ingested manure and feed for other animals purchased by the farms where the
BSE cases were discovered.
(2) It has been confirmed that the medications received by the 3
infected cows did not use any infectious materials.
1.2 Investigation of origin of imported MBM
1.2.1 England
Later investigations have shown that of the 333 tons of MBM imported from
England, 227.6 tons were imported by Japan, while the remaining 105.4 tons
went to other countries. There is a high likelihood that the portion
imported by Japan is made up of meal from animals other than ruminants.
1.2.2 Denmark
Factories in Denmark that produce MBM for export to Japan have been
employing a special thermal processing method (heated under saturated steam
conditions to a temperature of not less than 133 degrees C for a minimum of
20 minutes at an absolute pressure of 3 bar) since April 1997. Furthermore,
imports to Japan only started from December 1999. Since the 3 cows in
question were most likely infected during March and April 1998, it is
highly unlikely that the feed from Denmark is the source of the infection.
1.2.3 Italy
(1) It was learned that up until 1 Jun 1998, the Italian factories
making MBM feed for export to Japan were not using the special thermal
processing method. Their heating apparatus used a mechanism whereby the
steam does not come into direct contact with the MBM. Therefore, there is
the high possibility that before this time the pressure treatment standards
for insuring that potential causes of diseases are effectively kept inert
(humidity of 136 degrees C for 30 minutes) were not met.
(2) It was learned that the bulk of the MBM exported up until June 1998
was sold as material for pet food and fish feed. Even though the bulk of
the 105 tons of MBM imported in 1996 was probably used for poultry feed,
there remains the possibility that a portion was sold for other purposes.
(3) It cannot be determined whether the MBM produced in Italy before
June 1998 contained any abnormal prions. Furthermore, no connection between
the 3 BSE cases and imported MBM has been confirmed.
(4) However, MBM is still seen as one of the most likely sources of the
BSE infections. Therefore, it cannot be ruled out that MBM containing
abnormal prions through some means ended up at the farms where the BSE
cases were detected and somehow became mixed with the feed.
1.2.4 Asia
(1) The status of MBM imports from Asian countries (Hong Kong,
Thailand, Indonesia, the Philippines, Korea, Taiwan, China) was
investigated. It was found that the imported MBM is being safely used as
materials for feed in each of the relevant Asian countries. Furthermore, it
is very unlikely that MBM from other countries were unloaded in Asian
countries and then forwarded to Japan, because these materials are very
cheap to begin with and so little to no profit would be made after
accounting for the tariffs and commission fees.
(2) However, Hong Kong does not have such tariffs and so serves as a
popular intermediary for trade between countries. For this reason, it will
be necessary to continue investigating the aspects of the MBM imported from
Hong Kong.
II. Investigation of the Bovine Spongiform Encephalopathy (BSE) Infection
Agents and Routes for the 4th and 5th Cases
Since the Second Interim Report, 2 more cases of BSE were discovered in
Japan. The 4th case was detected on 13 May 2002 and the 5th case was
confirmed on 23 Aug 2002. The investigation has since been continued to
include these 2 new cases. The following is an outline of the investigation
up until now.
1. Status of Investigation
1.1 Investigation of farms where BSE was discovered
1.1.1 Records of infected cows
(1) The fourth infected cow was born in Hokkaido on 23 Mar 1996 and
slaughtered on 10 May 2002 at the age of 6 years 1 month.
(2) The fifth infected cow was born in Kanagawa Prefecture on 5 Dec
1995 and slaughtered on 21 Aug 2002 at the age of 6 years 8 months.
1.1.2 Investigation of cows living on same farm as infected cows
(1) Among the cows that had lived on the same farm as either the 4th or 5th
infected cow, and had already died or been destroyed, there was no evidence
of symptoms to suggest that they were infected with BSE.
(2) Still existing cows that had lived on the same farm as either the 4th
or 5th infected cow and showed symptoms similar to BSE were slaughtered and
inspected for BSE. All of the cases inspected up until now have been negative.
1.1.3 Investigation of feed
(A) Commonality of feeds
(1) The 4th and 5th infected cows were supplied with 2 of the same
brands of milk replacer produced at the same factory as the milk replacer
provided to the first 3 cows discovered to have BSE.
(2) The 4th infected cow received the same brand of formula feed as the
1st and 2nd infected cows.
(3) The 4th infected cow received the same brand of a formula feed as
the 2nd infected cow.
(4) The 4th infected cow received the same brand of supplementary feed
as the 1st and 2nd infected cows.
(B) MBM
The materials in the formula feeds and supplementary feeds used at the
farms where the 4th and 5th cases of BSE were discovered did not include
MBM. However, 2 of the factories producing the formula feed use MBM as a
material for pig and poultry feed (the factory cited for the 4th case of
BSE was also one of the factories in question for the 1st and 2nd cases).
Because the same factories were used for producing the cow, pig and poultry
feeds, and because it can not be confirmed that the lines were adequately
cleaned when switching between the production of the different feeds, the
possibility that MBM could have become mixed with the cow feed can not be
completely ruled out.
(C) Imported Animal Fats
(1) Animal fats with a possible connection to the 5th case of BSE,
imported up until June 1996, came from 2 factories belonging to "Company A"
in the Netherlands. However, the lines at both factories for producing
animal fats used in feeds are kept separate from all other lines for every
stage of the production process from the delivery of materials to storage.
Therefore, it is assumed that there is almost no possibility of the meal
becoming contaminated with animal proteins from other lines.
(2) The materials for these animal fats came from healthy animals.
However, some materials that cannot be used as food [for human
consumption], due to quality and other considerations, have been used.
These materials include back and abdominal fats, lungs and mammae [udders].
It was also learned that brains, spinal cords, eyes and other body parts
were voluntarily removed to meet customer needs (SRM removal became a legal
obligation from August 1997).
1.1.4 Other investigations
(1) The possibility is very remote that the infected cows somehow
ingested manure and feed for other animals purchased by the farms where the
BSE cases were discovered.
(2) It has been confirmed that the medications received by the 4th and
5th infected cows did not use any infectious materials.
--
Dr Shuichi Hamamoto
Deputy Director, Feed Division
Livestock Industry Department
Agricultural Production Bureau
Ministry of Agriculture, Forestry and Fisheries
Chiyoda-ku, Tokyo
<shuichi_hamamoto@nm.maff.go.jp>
[We are most obliged to Dr Hamamoto for this comprehensive, transparent,
and straightforward report. Previously, ProMED-mail has published a similar
report by the Danish authorities (see ref).
The Japanese investigation clearly illuminates the difficulties in
unfolding the sources of BSE introduction into non-EU countries, or into
countries (such as Austria, Finland, and Slovenia) that have previously
been regarded, according to the criteria of the Scientific Steering
Committee (SSC) of the EU, as "GBR II" ["it is unlikely, but cannot be
excluded, that one or several cattle that are (pre-clinically or
clinically) infected with the BSE agent are currently present in the
domestic herd" of the evaluated country].
The possible role of calf-milk-replacers, and specifically their animal-fat
ingredients, as possible sources of BSE infection, has been the subject of
several ProMED-mail postings. The SSC is expected to formulate its view on
the matter during its next meeting, 7-8 Nov 2002, under the agenda item
"Quantitative assessment of the risk of tallow, gelatine and dicalcium
phosphate". - Mod.AS]

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