tissues where the BSE infective agent would be found

if present. Other controls include banning nonambulatory disabled cattle from the human food chain; prohibiting air-injection stunning of slaughter cattle;

requiring additional process controls in advanced

meat-recovery systems; and forbidding the use of

mechanically separated meat in human food. Additionally, protection from BSE and other disease is

achieved through antemortem inspection of slaughter

cattle and the exclusion of animals with any clinical

signs of neurological disease or other abnormalities.

Surveillance and Monitoring

APHIS has conducted BSE surveillance since

1990, including an enhanced surveillance effort that

was initiated after an imported cow tested positive for

the disease in December 2003. The goal of the

enhanced effort, which began in June 2004, was to

test as many animals in a targeted population as 

possible over a 24-month period. This intensive effort

was intended to provide sufficient data to allow USDA

to more accurately estimate the prevalence or level of

BSE within the U.S. cattle population.

Analysis of the data collected over 7 years of

BSE surveillance shows that the prevalence of BSE

in 

ad

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inf

be 

lan

an

the 

for 

1 

su

An

Ed

or

cli

sh

as

St

ind

tio

ab

ind

sh

dis

ex

ind

Figure 5—Vacuoles—microscopic holes in the grey matter—

give the brain of BSE-affected cows a spongelike appearance when tissue sections are examined in the lab.
Introduction

Bovine spongiform encephalopathy (BSE), widely referred

to as "mad cow disease," is a chronic degenerative disease affecting the central nervous system of cattle. The

disease was first diagnosed in 1986 in the United Kingdom. Since that time, it has been found in many European countries, and also in countries outside of Europe,

including Japan, Canada, and the United States. To date,

however, more than 95 percent of the total cases worldwide have occurred in the United Kingdom.

What Causes BSE and How It 

Progresses

BSE is a progressive and fatal neurological disease of

cattle caused by an unconventional transmissible agent.

BSE belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs). In addition to

BSE, TSEs include scrapie, which affects sheep and

goats; transmissible mink encephalopathy; chronic wasting

disease of deer and elk; and in humans, kuru, both classic

and variant Creutzfeldt–Jakob disease (CJD), 

Gerstmann–Straussle–Scheinker syndrome, and fatal

familial insomnia.

The agents that cause BSE and other TSEs have yet

to be fully characterized. The theory most widely 

accepted in the scientific community is that the agent is a 

prion–an abnormal protein. The BSE agent is extremely

resistant to heat and to normal sterilization processes. It

also does not evoke any detectable immune response or

inflammatory reaction in host animals.

Cattle affected by BSE experience progressive

degeneration of the nervous system. Affected animals

may display nervousness or aggression, abnormal posture, difficulty in coordination and rising, decreased milk

production, or loss of body weight despite continued

appetite. All infected cattle die. There is neither any treatment nor a vaccine to prevent the disease.
Introduction

Bovine spongiform encephalopathy (BSE), widely referred

to as "mad cow disease," is a chronic degenerative disease affecting the central nervous system of cattle. The

disease was first diagnosed in 1986 in the United Kingdom. Since that time, it has been found in many European countries, and also in countries outside of Europe,

including Japan, Canada, and the United States. To date,

however, more than 95 percent of the total cases worldwide have occurred in the United Kingdom.

What Causes BSE and How It 

Progresses

BSE is a progressive and fatal neurological disease of

cattle caused by an unconventional transmissible agent.

BSE belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs). In addition to

BSE, TSEs include scrapie, which affects sheep and

goats; transmissible mink encephalopathy; chronic wasting

disease of deer and elk; and in humans, kuru, both classic

and variant Creutzfeldt–Jakob disease (CJD), 

Gerstmann–Straussle–Scheinker syndrome, and fatal

familial insomnia.

The agents that cause BSE and other TSEs have yet

to be fully characterized. The theory most widely 

accepted in the scientific community is that the agent is a 

prion–an abnormal protein. The BSE agent is extremely

resistant to heat and to normal sterilization processes. It

also does not evoke any detectable immune response or

inflammatory reaction in host animals.

Cattle affected by BSE experience progressive

degeneration of the nervous system. Affected animals

may display nervousness or aggression, abnormal posture, difficulty in coordination and rising, decreased milk

production, or loss of body weight despite continued

appetite. All infected cattle die. There is neither any treatment nor a vaccine to prevent the disease.
Introduction

Bovine spongiform encephalopathy (BSE), widely referred

to as "mad cow disease," is a chronic degenerative disease affecting the central nervous system of cattle. The

disease was first diagnosed in 1986 in the United Kingdom. Since that time, it has been found in many European countries, and also in countries outside of Europe,

including Japan, Canada, and the United States. To date,

however, more than 95 percent of the total cases worldwide have occurred in the United Kingdom.

What Causes BSE and How It 

Progresses

BSE is a progressive and fatal neurological disease of

cattle caused by an unconventional transmissible agent.

BSE belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs). In addition to

BSE, TSEs include scrapie, which affects sheep and

goats; transmissible mink encephalopathy; chronic wasting

disease of deer and elk; and in humans, kuru, both classic

and variant Creutzfeldt–Jakob disease (CJD), 

Gerstmann–Straussle–Scheinker syndrome, and fatal

familial insomnia.

The agents that cause BSE and other TSEs have yet

to be fully characterized. The theory most widely 

accepted in the scientific community is that the agent is a 

prion–an abnormal protein. The BSE agent is extremely

resistant to heat and to normal sterilization processes. It

also does not evoke any detectable immune response or

inflammatory reaction in host animals.

Cattle affected by BSE experience progressive

degeneration of the nervous system. Affected animals

may display nervousness or aggression, abnormal posture, difficulty in coordination and rising, decreased milk

production, or loss of body weight despite continued

appetite. All infected cattle die. There is neither any treatment nor a vaccine to prevent the disease.
Introduction

Bovine spongiform encephalopathy (BSE), widely referred

to as "mad cow disease," is a chronic degenerative disease affecting the central nervous system of cattle. The

disease was first diagnosed in 1986 in the United Kingdom. Since that time, it has been found in many European countries, and also in countries outside of Europe,

including Japan, Canada, and the United States. To date,

however, more than 95 percent of the total cases worldwide have occurred in the United Kingdom.

What Causes BSE and How It 

Progresses

BSE is a progressive and fatal neurological disease of

cattle caused by an unconventional transmissible agent.

BSE belongs to the family of diseases known as transmissible spongiform encephalopathies (TSEs). In addition to

BSE, TSEs include scrapie, which affects sheep and

goats; transmissible mink encephalopathy; chronic wasting

disease of deer and elk; and in humans, kuru, both classic

and variant Creutzfeldt–Jakob disease (CJD), 

Gerstmann–Straussle–Scheinker syndrome, and fatal

familial insomnia.

The agents that cause BSE and other TSEs have yet

to be fully characterized. The theory most widely 

accepted in the scientific community is that the agent is a 

prion–an abnormal protein. The BSE agent is extremely

resistant to heat and to normal sterilization processes. It

also does not evoke any detectable immune response or

inflammatory reaction in host animals.

Cattle affected by BSE experience progressive

degeneration of the nervous system. Affected animals

may display nervousness or aggression, abnormal posture, difficulty in coordination and rising, decreased milk

production, or loss of body weight despite continued

appetite. All infected cattle die. There is neither any treatment nor a vaccine to prevent the disease.
Introduction

Bovine spongiform encephalopathy (BSE), widely referre

to as "mad cow disease," is a chronic degenerative disease affecting the central nervous system of cattle. The

disease was first diagnosed in 1986 in the United Kingdom. Since that time, it has been found in many European countries, and also in countries outside of Europe,

including Japan, Canada, and the United States. To dat

however, more than 95 percent of the total cases worldwide have occurred in the United Kingdom.

What Causes BSE and How It 

Progresses

BSE is a progressive and fatal neurological disease of

cattle caused by an unconventional transmissible agent.

BSE belongs to the family of diseases known as transm

sible spongiform encephalopathies (TSEs). In addition t

BSE, TSEs include scrapie, which affects sheep and

goats; transmissible mink encephalopathy; chronic wasti

disease of deer and elk; and in humans, kuru, both clas

and variant Creutzfeldt–Jakob disease (CJD), 

Gerstmann–Straussle–Scheinker syndrome, and fatal

familial insomnia.

The agents that cause BSE and other TSEs have y

to be fully characterized. The theory most widely 

accepted in the scientific community is that the agent is 

prion–an abnormal protein. The BSE agent is extremely

resistant to heat and to normal sterilization processes. 

also does not evoke any detectable immune response o

inflammatory reaction in host animals.

Cattle affected by BSE experience progressive

degeneration of the nervous system. Affected animals

may display nervousness or aggression, abnormal posture, difficulty in coordination and rising, decreased milk

production, or loss of body weight despite continued

appetite. All infected cattle die. There is neither any tre

ment nor a vaccine to prevent the disease.
tissues where the BSE infective agent would be found

if present. Other controls include banning nonambulatory disabled cattle from the human food chain; prohibiting air-injection stunning of slaughter cattle;

requiring additional process controls in advanced

meat-recovery systems; and forbidding the use of

mechanically separated meat in human food. Additionally, protection from BSE and other disease is

achieved through antemortem inspection of slaughter

cattle and the exclusion of animals with any clinical

signs of neurological disease or other abnormalities.

Surveillance and Monitoring

APHIS has conducted BSE surveillance since

1990, including an enhanced surveillance effort that

was initiated after an imported cow tested positive for

the disease in December 2003. The goal of the

enhanced effort, which began in June 2004, was to

test as many animals in a targeted population as 

possible over a 24-month period. This intensive effort

was intended to provide sufficient data to allow USDA

to more accurately estimate the prevalence or level of

BSE within the U.S. cattle population.

Analysis of the data collected over 7 years of

BSE surveillance shows that the prevalence of BSE

Figure 5—Vacuoles—microscopic holes in the grey matter—

give the brain of BSE-affected cows a spongelike appearance when tissue sections are examined in the lab.
tissues where the BSE infective agent would be found

if present. Other controls include banning nonambulatory disabled cattle from the human food chain; prohibiting air-injection stunning of slaughter cattle;

requiring additional process controls in advanced

meat-recovery systems; and forbidding the use of

mechanically separated meat in human food. Additionally, protection from BSE and other disease is

achieved through antemortem inspection of slaughter

cattle and the exclusion of animals with any clinical

signs of neurological disease or other abnormalities.

Surveillance and Monitoring

APHIS has conducted BSE surveillance since

1990, including an enhanced surveillance effort that

was initiated after an imported cow tested positive for

the disease in December 2003. The goal of the

enhanced effort, which began in June 2004, was to

test as many animals in a targeted population as 

possible over a 24-month period. This intensive effort

was intended to provide sufficient data to allow USDA

to more accurately estimate the prevalence or level of

BSE within the U.S. cattle population.

Analysis of the data collected over 7 years of

BSE surveillance shows that the prevalence of BSE

Figure 5—Vacuoles—microscopic holes in the grey matter—

give the brain of BSE-affected cows a spongelike appearance when tissue sections are examined in the lab.
tissues where the BSE infective agent would be found

if present. Other controls include banning nonambulatory disabled cattle from the human food chain; prohibiting air-injection stunning of slaughter cattle;

requiring additional process controls in advanced

meat-recovery systems; and forbidding the use of

mechanically separated meat in human food. Additionally, protection from BSE and other disease is

achieved through antemortem inspection of slaughter

cattle and the exclusion of animals with any clinical

signs of neurological disease or other abnormalities.

Surveillance and Monitoring

APHIS has conducted BSE surveillance since

1990, including an enhanced surveillance effort that

was initiated after an imported cow tested positive for

the disease in December 2003. The goal of the

enhanced effort, which began in June 2004, was to

test as many animals in a targeted population as 

possible over a 24-month period. This intensive effort

was intended to provide sufficient data to allow USDA

to more accurately estimate the prevalence or level of

BSE within the U.S. cattle population.

Analysis of the data collected over 7 years of

BSE surveillance shows that the prevalence of BSE

Figure 5—Vacuoles—microscopic holes in the grey matter—

give the brain of BSE-affected cows a spongelike appearance when tissue sections are examined in the lab.
tissues where the BSE infective agent would be found

if present. Other controls include banning nonambulatory disabled cattle from the human food chain; prohibiting air-injection stunning of slaughter cattle;

requiring additional process controls in advanced

meat-recovery systems; and forbidding the use of

mechanically separated meat in human food. Additionally, protection from BSE and other disease is

achieved through antemortem inspection of slaughter

cattle and the exclusion of animals with any clinical

signs of neurological disease or other abnormalities.

Surveillance and Monitoring

APHIS has conducted BSE surveillance since

1990, including an enhanced surveillance effort that

was initiated after an imported cow tested positive for

the disease in December 2003. The goal of the

enhanced effort, which began in June 2004, was to

test as many animals in a targeted population as 

possible over a 24-month period. This intensive effort

was intended to provide sufficient data to allow USDA

to more accurately estimate the prevalence or level of

BSE within the U.S. cattle population.

Analysis of the data collected over 7 years of

BSE surveillance shows that the prevalence of BSE

in 

a

a

in

b

la

a

th

fo

1 

s

A

E

o

c

s

a

S

in

tio

a

in

s

d

ex

in

Figure 5—Vacuoles—microscopic holes in the grey matter—

give the brain of BSE-affected cows a spongelike appearance when tissue sections are examined in the lab.