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From: TSS ()
Subject: Report on Food & Drug Administration Dallas District Investigation of Bovine Spongiform Encephalopathy Event in Texas 2005
Date: August 30, 2005 at 2:15 pm PST

Report on Food & Drug Administration Dallas District Investigation of
Bovine Spongiform Encephalopathy Event in Texas 2005

Executive Summary:

On June 24, 2005, USDA informed FDA that a cow in Texas tested positive for Bovine Spongiform Encephalopathy (BSE). Information provided by APHIS was that the BSE positive cow was born and raised in a herd in Texas and was approximately 12 years old. The animal was sampled for BSE at a pet food plant in Texas on November 15, 2004, as part of USDA’s enhanced surveillance program. The animal was disposed of by incineration and did not enter the human food or animal feed chains. Although the positive animal posed no risk to the animal feed supply, FDA, APHIS, the Texas Animal Health Commission (TAHC), and the Texas Feed and Fertilizer Control Service (TFFCS) conducted a feed investigation with two main objectives. The first objective was to identify all protein sources in the animal’s feed history that could potentially have been the source of the BSE agent. The second objective was to verify that cattle leaving the herd after 1997 that were identified by USDA/APHIS as animals of concern (e.g. progeny and feed cohorts), were rendered at facilities in compliance with the regulation (21 CFR 589.2000) that prohibits most mammalian protein in feed for ruminants that became effective August 4, 1997 (herein called BSE/Ruminant Feed rule).

The feed history investigation identified 21 feed products that had been used on the farm since 1990. These feed products were purchased from three retail feed stores and had been manufactured at nine different feed mills. The investigators visited these establishments to collect information on formulations, shipping invoices, and use of ruminant meat and bone meal (MBM) on the premises both pre-1997 feed ban and post-1997 feed ban. This investigation found no feed products used on the farm since 1997 that had been formulated to contain prohibited mammalian protein.

The investigation identified one feed which contained an animal protein source that could not be identified. The investigation also found one feed mill that supplied feed to the farm that had used ruminant MBM in feed formulations for non-ruminant species after the BSE/Ruminant Feed rule went into effect, which is permitted under the rule, and that several feed mills had used ruminant MBM in feeds prior to the feed ban. Although the investigation did not identify a specific feed source as the likely cause of this animal’s infection, it is probable that the most likely route of exposure for this animal was consumption of an animal feed containing mammalian protein prior to the implementation of the BSE/Ruminant Feed rule in 1997.

The investigation into the disposition of herd mates from this farm involved visits to nine slaughter plants and eight rendering plants. The investigation found that all rendering plants were operating in compliance with the BSE/ruminant feed ban regulation. A review of the inspection history of each of these rendering firms found no violations.

Background of Investigation:

When notified on June 24, 2005, FDA Headquarters and Dallas District management officials immediately began making contacts with their Federal, State and Local counterparts to plan for and initiate follow-up investigational activities to determine the feed history in this herd and to assure the safety of the animal feed supply by evaluating current and historic compliance with the BSE/ruminant feed ban rule.

APHIS established a joint Incident Command Post and FDA Dallas District staffed this post full time with a Supervisory Investigator charged with coordinating activities between FDA, APHIS, TAHC and TFFCS. Coordination conference calls were set up with all Federal and State agencies involved in the investigation to keep everyone apprised of investigational developments.

Animal Tracing Activities and Renderer Follow-up Inspections:

One of APHIS’ primary objectives was to identify and trace the animals of interest (animals of interest would include any animals which could have been potential birth cohorts or feed cohorts of the index animal, or potential offspring of the index animal within the two years prior to the positive diagnosis) from the index herd. This objective included the identification of points of sale and ultimately the actual slaughter facilities for animals of interest that left the farm. As the trace information was developed, APHIS shared this information with FDA. Further information on animal of interest identification and tracing can be found in the USDA Texas BSE Final Epidemiology report.

APHIS identified nine slaughter establishments receiving these animals of interest. Eight of the slaughter establishments were located in the State of Texas and one was located in the State of Georgia. Dallas District Investigators notified USDA/FSIS of our plans to visit each slaughter establishment to identify rendering facilities receiving materials from these slaughter establishments during the timeframe they received animals of interest. Dallas District also issued an assignment to Atlanta District to visit and inspect the one slaughter/renderer establishment located in the State of Georgia.

Eight renderers and one protein source broker were identified as receiving materials from these slaughter establishments. Each rendering facility identified was inspected for current compliance with the mammalian protein feed ban rule. Each firm’s operations during the period of time of receipt of these animals post 1997 were evaluated from a historical viewpoint and no evidence of noncompliance was detected.

In all, FDA visited nine slaughter facilities, eight rendering facilities and one broker of these materials. All facilities inspected were found to be in compliance with the BSE/ruminant feed ban rule

Following is a graphical representation of the animal product follow-up work performed.

Feed Investigation:

As information was learned about the index herd, FDA Investigators working with TAHC officials conducted multiple interviews with the producer of the animal regarding possible feeds, feed sources, animal husbandry practices, and other events which may have changed normal feeding practices over the course of the index animal’s life in the herd and any other information which may have been helpful in identifying the possible sources of feed for this animal and herd. FDA corroborated this information through interviews at the retail feed supply stores where the producer purchased feeds.

Follow-up at these retail feed supply stores identified 21 possible feed products the producer may have used during the history of the herd. Fifteen purchased feed products were identified, along with hay, native grass, rice straw, soybean meal, milk replacer/colostrum and bagged corn. These products were identified as originating from nine different manufacturers. Each of these manufacturers was inspected by FDA Dallas District and TFFCS Investigators.

Feed manufacturers were located throughout the State of Texas. An assignment was also issued to another FDA District to visit a Corporate Headquarters facility in an effort to review archived feed formulations and labels. During each of these inspections, the firm’s current compliance with the BSE/ruminant feed ban rule was evaluated and attempts were made to determine the protein sources used in feeds on the index farm. Many of the feeds investigated were manufactured and used prior to the implementation of the BSE/ruminant feed ban rule in 1997. Feed products of particular interest included any which may have contained a protein source and the primary focus was on identifying any possible mammalian protein source material in those feed products. We found that ruminant feeds that had contained mammalian meat and bone meal (MBM) prior to the BSE/ruminant feed ban rule had been discontinued or reformulated upon the implementation of these rules. There is no regulatory requirement for a feed mill to archive formulations for that length of time, so in those instances where an actual formulation could not be obtained, experienced employees of the firms were interviewed and their recollections recorded.

Of all the feeds in use by the producer since 1997, none were discovered to have contained prohibited material (mammalian protein). Since the age of the index animal was determined to be approximately 12 years, investigating and reconstructing a feed history over such a long period of time is challenging. This ranch is a beef cow-calf operation and minimal feed records were maintained. Due to the nature of this investigation, it is difficult to determine what feeds were in use at specific times and what the formulation of those feeds were at the time they were fed. A feed history was developed through interviews with the producer and other farm personnel since they did not maintain any feed history documentation. Interviews with personnel at retail establishments disclosed incomplete records and cash sales that did not always identify the purchaser. Dallas District investigated any and all feed ingredients that were identified as being fed or potentially fed over the course of the last 15 years of this herd’s operation. Feeds discovered during this investigation with potential mammalian protein sources are as below:

One feed, used prior to 1996, before the implementation of the feed ban, was suspected to contain mammalian meat and bone meal, but this could not be confirmed as no formulation records were available.

The producer recalled using a particular feed sporadically during the 1980’s and 1990’s, however, he could not remember the name or manufacturer of the feed and had no records identifying the product. It is not known whether this feed contained an animal protein source. Attempts to identify this feed through interviews with retail sources were unsuccessful.

The producer identified one feed product that has been used since the year 2000 which contains fish meal as a protein source. Further investigation revealed that this product had contained mammalian meat and bone meal prior to 1997, but that it had been reformulated at that time using fish meal to replace the MBM.

A tabular representation of the feed inspection follow-up activities is presented below:

Dates of Use
Protein Source
Current BSE Inspection
BSE Compliance History

Feed #1 - Range Meal
1980’s - 2000
Unknown - Unable to determine actual manufacturer, no records available from producer

Feed #2 - High Protein Starter Feed
2001 to present
Feather meal
BSE Compliant
BSE Compliant

Feed #3 - High Protein Starter Feed
~1995 - 2001
Feather meal
BSE Compliant
BSE Compliant

Feed #4 - Cottonseed cake
Prior to 1990
Cottonseed meal
BSE Compliant
BSE Compliant

Feed #5 - Cottonseed cake
Early 1980’s - 1990’s
Cottonseed meal
BSE Compliant
BSE Compliant

Feed #6 - Limiter
2001 to present
Feather meal
BSE Compliant
BSE Compliant

Feed #7 - Creep pellets
Prior to 1970
Likely feather meal - no formulation could be obtained

Feed #8 - Lick tub
Since 2000
MBM prior to 1997 Fish Meal since 1997
BSE Compliant
BSE Compliant

Feed #9 - Cottonseed meal
Cottonseed meal
BSE Compliant
BSE Compliant

Feed #10 - Range Cubes
Continuously since 1990
Feather meal
BSE Compliant
BSE Compliant[1]

Feed #11 - Sulfur Salt Block
Minerals; calcium - all non-animal derived
BSE Compliant
BSE Compliant

Feed #12 - Lick tub
Continuously since 1995
Feather meal
BSE Compliant
BSE Compliant

Feed #13 - Beef Supplement
Prior to 1996
Prior to 1997, suspect MBM - Not able to confirm, no formulation available
BSE Compliant
Same manufacturer as Feed #10[1]

Feed #14 - Mineralized Salt
Continuously since 1998
Minerals; calcium - all non-animal derived
BSE Compliant
BSE Compliant

Feed #15 - Soybean meal
Since 2000, sparingly
Soybean meal

Feed #16 - Corn

Feed #17 - Rice straw
1996, during dry year
Rice straw

Feed #18 - Hay

Feed #19 - Milk Replacer
Since 2000, Infrequent use
Dehydrated colostrums, whey

Feed #20 - Grass
Native grass

Feed #21 - Soybean meal
Since 2000, sparingly
Soybean meal

Dallas District previously documented one incident of the accidental addition of mammalian protein to a feed that was to be used for cattle at this facility. This incident was isolated to the manufacture of one lot of a custom cattle feed. A cross contamination error resulted in mammalian meat and bone meal being accidentally included in a feed. The error was detected soon after production. The firm acted swiftly in recalling the product and purchasing the animals that had consumed the feed. No products entered the human food or ruminant feed chain.

Dallas District Compliance History with BSE Feed Ban Rules:

Prior to 1997, feed manufacturers were not required to differentiate between protein sources used in ruminant and non-ruminant feeds. For a period of time following the implementation of the BSE/ruminant feed ban rule, some feed manufacturers continued to use both prohibited material and non-prohibited material within the same facility, employing separation and cleanout procedures to minimize cross-contamination. Although the regulations allow this practice, the potential for cross-contamination of ruminant feeds is greater. Most feed mills have found this practice to be difficult and have abandoned this practice.

Since the implementation of the BSE/ruminant feed ban rule in 1997, Dallas District and its State partners have inspected every known or registered feed manufacturer located in the states of Texas, Oklahoma and Arkansas. Further, every rendering operation and feed manufacturer actually processing with prohibited materials has been inspected annually. The compliance rate of the industry has been excellent.


In total FDA, along with TFFCS, conducted 33 inspections, investigations and interviews of the producer, retail feed establishments, feed manufacturers, corporate headquarters, slaughter facilities, renderers and a protein source broker. The FDA Dallas District follow-up to this incident resulted in the coordination of efforts of multiple Federal and State agencies. This report is the physical output of many hours of research, planning and coordination. All of the inspections conducted confirmed the feed manufacturers and rendering operations to be in compliance with the current BSE/ruminant feed ban rule.

Dallas District conducts annual inspections of all feed mills and rendering facilities who handle, use or produce PM for feed use. Inspections performed since the initiation of the BSE/ruminant feed ban rules in 1997 have confirmed a high degree of industry wide compliance with these important safeguards. The district also routinely coordinates and shares information regarding feed inspections with the TFFCS who are also responsible for the evaluating feed ban compliance in the state of Texas.

Food and Drug Administration
August 30, 2005

FDA Statement
May 4, 2004
Media Inquiries: 301-827-6242
Consumer Inquiries: 888-INFO-FDA

Statement on Texas Cow With Central Nervous System Symptoms
On Friday, April 30 th , the Food and Drug Administration learned that a cow
with central nervous system symptoms had been killed and shipped to a
processor for rendering into animal protein for use in animal feed.

FDA, which is responsible for the safety of animal feed, immediately began
an investigation. On Friday and throughout the weekend, FDA investigators
inspected the slaughterhouse, the rendering facility, the farm where the
animal came from, and the processor that initially received the cow from the

FDA's investigation showed that the animal in question had already been
rendered into "meat and bone meal" (a type of protein animal feed). Over the
weekend FDA was able to track down all the implicated material. That
material is being held by the firm, which is cooperating fully with FDA.

Cattle with central nervous system symptoms are of particular interest
because cattle with bovine spongiform encephalopathy or BSE, also known as
"mad cow disease," can exhibit such symptoms. In this case, there is no way
now to test for BSE. But even if the cow had BSE, FDA's animal feed rule
would prohibit the feeding of its rendered protein to other ruminant animals
(e.g., cows, goats, sheep, bison).

FDA is sending a letter to the firm summarizing its findings and informing
the firm that FDA will not object to use of this material in swine feed
only. If it is not used in swine feed, this material will be destroyed. Pigs
have been shown not to be susceptible to BSE. If the firm agrees to use the
material for swine feed only, FDA will track the material all the way
through the supply chain from the processor to the farm to ensure that the
feed is properly monitored and used only as feed for pigs.

To protect the U.S. against BSE, FDA works to keep certain mammalian protein
out of animal feed for cattle and other ruminant animals. FDA established
its animal feed rule in 1997 after the BSE epidemic in the U.K. showed that
the disease spreads by feeding infected ruminant protein to cattle.

Under the current regulation, the material from this Texas cow is not
allowed in feed for cattle or other ruminant animals. FDA's action
specifying that the material go only into swine feed means also that it will
not be fed to poultry.

FDA is committed to protecting the U.S. from BSE and collaborates closely
with the U.S. Department of Agriculture on all BSE issues. The animal feed
rule provides crucial protection against the spread of BSE, but it is only
one of several such firewalls. FDA will soon be improving the animal feed
rule, to make this strong system even stronger.




January 30, 2001
Print Media: 301-827-6242
Consumer Inquiries: 888-INFO-FDA


Note: On Dec. 23, 2003, the U.S. Department of Agriculture reported that a
cow in Washington state had tested positive for bovine spongiform
encephalopathy (BSE, or mad cow disease). As a result, information on this
Web page stating that no BSE cases had been found in the United States is
now incorrect. However, because other information on this page continues to
have value, the page will remain available for viewing.


Today the Food and Drug Administration announced the results of tests taken
on feed used at a Texas feedlot that was suspected of containing meat and
bone meal from other domestic cattle -- a violation of FDA's 1997
prohibition on using ruminant material in feed for other ruminants. Results
indicate that a very low level of prohibited material was found in the feed
fed to cattle.

FDA has determined that each animal could have consumed, at most and in
total, five-and-one-half grams - approximately a quarter ounce -- of
prohibited material. These animals weigh approximately 600 pounds.

It is important to note that the prohibited material was domestic in origin
(therefore not likely to contain infected material because there is no
evidence of BSE in U.S. cattle), fed at a very low level, and fed only once.
The potential risk of BSE to such cattle is therefore exceedingly low, even
if the feed were contaminated.

According to Dr. Bernard Schwetz, FDA's Acting Principal Deputy
Commissioner, "The challenge to regulators and industry is to keep this
disease out of the United States. One important defense is to prohibit the
use of any ruminant animal materials in feed for other ruminant animals.
Combined with other steps, like U.S. Department of Agriculture's (USDA) ban
on the importation of live ruminant animals from affected countries, these
steps represent a series of protections, to keep American cattle free of

Despite this negligible risk, Purina Mills, Inc., is nonetheless announcing
that it is voluntarily purchasing all 1,222 of the animals held in Texas and
mistakenly fed the animal feed containing the prohibited material.
Therefore, meat from those animals will not enter the human food supply. FDA
believes any cattle that did not consume feed containing the prohibited
material are unaffected by this incident, and should be handled in the beef
supply clearance process as usual.

FDA believes that Purina Mills has behaved responsibly by first reporting
the human error that resulted in the misformulation of the animal feed
supplement and then by working closely with State and Federal authorities.

This episode indicates that the multi-layered safeguard system put into
place is essential for protecting the food supply and that continued
vigilance needs to be taken, by all concerned, to ensure these rules are
followed routinely.

FDA will continue working with USDA as well as State and local officials to
ensure that companies and individuals comply with all laws and regulations
designed to protect the U.S. food supply.

Risk of oral infection with bovine spongiform encephalopathy agent in

Corinne Ida Lasmézas, Emmanuel Comoy, Stephen Hawkins, Christian Herzog,
Franck Mouthon, Timm Konold, Frédéric Auvré, Evelyne Correia, Nathalie
Lescoutra-Etchegaray, Nicole Salès, Gerald Wells, Paul Brown, Jean-Philippe
Summary The uncertain extent of human exposure to bovine spongiform
encephalopathy (BSE)--which can lead to variant Creutzfeldt-Jakob disease
(vCJD)--is compounded by incomplete knowledge about the efficiency of oral
infection and the magnitude of any bovine-to-human biological barrier to
transmission. We therefore investigated oral transmission of BSE to
non-human primates. We gave two macaques a 5 g oral dose of brain homogenate
from a BSE-infected cow. One macaque developed vCJD-like neurological
disease 60 months after exposure, whereas the other remained free of disease
at 76 months. On the basis of these findings and data from other studies, we
made a preliminary estimate of the food exposure risk for man, which
provides additional assurance that existing public health measures can
prevent transmission of BSE to man.

Published online January 27, 2005

It is clear that the designing scientists must

also have shared Mr Bradley's surprise at the results because all the dose

levels right down to 1 gram triggered infection.


6. It also appears to me that Mr Bradley's answer (that it would take less
than say 100

grams) was probably given with the benefit of hindsight; particularly if one

considers that later in the same answer Mr Bradley expresses his surprise
that it

could take as little of 1 gram of brain to cause BSE by the oral route
within the

same species. This information did not become available until the "attack

experiment had been completed in 1995/96. This was a titration experiment

designed to ascertain the infective dose. A range of dosages was used to

that the actual result was within both a lower and an upper limit within the

and the designing scientists would not have expected all the dose levels to

infection. The dose ranges chosen by the most informed scientists at that

ranged from 1 gram to three times one hundred grams. It is clear that the

scientists must have also shared Mr Bradley's surprise at the results
because all the

dose levels right down to 1 gram triggered infection.

Re: BSE .1 GRAM LETHAL NEW STUDY SAYS via W.H.O. Dr Maura Ricketts

[BBC radio 4 FARM news]

2) Infectious dose:

To cattle: 1 gram of infected brain material (by oral ingestion)


Medical Sciences
Identification of a second bovine amyloidotic spongiform encephalopathy:
Molecular similarities with sporadic Creutzfeldt-Jakob disease

Cristina Casalone *, Gianluigi Zanusso , Pierluigi Acutis *, Sergio Ferrari
, Lorenzo Capucci , Fabrizio Tagliavini ¶, Salvatore Monaco ||, and Maria
Caramelli *

*Centro di Referenza Nazionale per le Encefalopatie Animali, Istituto
Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via
Bologna, 148, 10195 Turin, Italy; Department of Neurological and Visual
Science, Section of Clinical Neurology, Policlinico G.B. Rossi, Piazzale
L.A. Scuro, 10, 37134 Verona, Italy; Istituto Zooprofilattico Sperimentale
della Lombardia ed Emilia Romagna, Via Bianchi, 9, 25124 Brescia, Italy; and
¶Istituto Nazionale Neurologico "Carlo Besta," Via Celoria 11, 20133 Milan,

Edited by Stanley B. Prusiner, University of California, San Francisco, CA,
and approved December 23, 2003 (received for review September 9, 2003)

Transmissible spongiform encephalopathies (TSEs), or prion diseases, are
mammalian neurodegenerative disorders characterized by a posttranslational
conversion and brain accumulation of an insoluble, protease-resistant
isoform (PrPSc) of the host-encoded cellular prion protein (PrPC). Human and
animal TSE agents exist as different phenotypes that can be biochemically
differentiated on the basis of the molecular mass of the protease-resistant
PrPSc fragments and the degree of glycosylation. Epidemiological, molecular,
and transmission studies strongly suggest that the single strain of agent
responsible for bovine spongiform encephalopathy (BSE) has infected humans,
causing variant Creutzfeldt-Jakob disease. The unprecedented biological
properties of the BSE agent, which circumvents the so-called "species
barrier" between cattle and humans and adapts to different mammalian
species, has raised considerable concern for human health. To date, it is
unknown whether more than one strain might be responsible for cattle TSE or
whether the BSE agent undergoes phenotypic variation after natural
transmission. Here we provide evidence of a second cattle TSE. The disorder
was pathologically characterized by the presence of PrP-immunopositive
amyloid plaques, as opposed to the lack of amyloid deposition in typical BSE
cases, and by a different pattern of regional distribution and topology of
brain PrPSc accumulation. In addition, Western blot analysis showed a PrPSc
type with predominance of the low molecular mass glycoform and a
protease-resistant fragment of lower molecular mass than BSE-PrPSc.
Strikingly, the molecular signature of this previously undescribed bovine
PrPSc was similar to that encountered in a distinct subtype of sporadic
Creutzfeldt-Jakob disease.


C.C. and G.Z. contributed equally to this work.

||To whom correspondence should be addressed.

E-mail: .

1: J Infect Dis 1980 Aug;142(2):205-8

Oral transmission of kuru, Creutzfeldt-Jakob disease, and scrapie to
nonhuman primates.

Gibbs CJ Jr, Amyx HL, Bacote A, Masters CL, Gajdusek DC.

Kuru and Creutzfeldt-Jakob disease of humans and scrapie disease of sheep
and goats were transmitted to squirrel monkeys (Saimiri sciureus) that were
exposed to the infectious agents only by their nonforced consumption of
known infectious tissues. The asymptomatic incubation period in the one
monkey exposed to the virus of kuru was 36 months; that in the two monkeys
exposed to the virus of Creutzfeldt-Jakob disease was 23 and 27 months,
respectively; and that in the two monkeys exposed to the virus of scrapie
was 25 and 32 months, respectively. Careful physical examination of the
buccal cavities of all of the monkeys failed to reveal signs or oral
lesions. One additional monkey similarly exposed to kuru has remained
asymptomatic during the 39 months that it has been under observation.

PMID: 6997404


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