Bovine Tuberculosis Eradication Program
Historical Perspective
Mitchell Palmer, DVM, PhD and W. Ray Waters, DVM, PhDNational Animal Disease Center
USDA, ARS
Mark S. Camacho, DVM, MPHRegional Epidemiologist
USDA, APHIS, Veterinary Services
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Tuberculosis- Ancient Origins
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Ancient history of tuberculosis
The earliest detection of Mycobacterium tuberculosis is in the remains of bison dated 18,000 years before the present.
Skeletal remains show prehistoric humans (4000 BC) had TB, and tubercular decay has been found in the spines of mummies from 3000–2400 BC.
Source: Wikipedia
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Ancient History of Tuberculosis
“Phthisis” (wasting away) is a Greek term for tuberculosis; around 460 BC, Hippocrates identified phthisis as the most widespread disease of the times involving coughing up blood and fever, which was almost always fatal.-
Hippocrates (460-370 BC)
“Why when one comes near consumptives… does one contract their disease…the reason is that the breath is bad and heavy…one breathes this pernicious air and takes in the disease because there is in the air something disease producing.” Aristotle (384-322 BC)
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“Consumption” and “White Plague”
Disease appears to “consume” it’s victims… causing them to waste away.
Tuberculous patients appear pale.
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Human Tuberculosis- The Numbers
19th Century- 20% of all human deaths were caused by tuberculosis.
21st Century- 2 billion infected worldwide.
Annually: 8-9 million new cases, 1.5 million die.
10-15 thousand cases/yr in the US.
Most cases are due to “reactivation”.
Disease of Poverty
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Country All Cases Per 100,000
India 2,200,000 189
China 1,000,000 75
South Africa 500,000 993
Cambodia 61,000 424
Indonesia 450,000 187
Pakistan 410,000 231
Bangladesh 340,000 225
Ethiopia 220,000 258
Europe 380,000 42
United States 9,951 3.2
Global total 8,700,000 125
Uncommon in wealthy western countries today.
Still rampant in the world’s poorest countries.
Bovine Tuberculosis
“There is scarcely a subject related to agriculture or public health that has occasioned as much or as bitter discussion, or has led to the expression of so many divergent views as this one of tuberculosis in cattle.” Leonard Pearson (1905)
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Mycobacterium tuberculosis complex
M. tuberculosis
M. canetti
M. africanum
M. pinnipedii
M. bovis Broadest host range
M. bovis and M. tuberculosis shared a common ancestor
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Bovine Tuberculosis- The Numbers
Pigs, goats, sheep, camelids, horses, sheep, dogs, cats. Livestock worldwide (cattle, Asiatic water buffalo).
69% of countries in tropics. 80% of countries in Africa. One of the most important livestock diseases in China.
Estimate 1 billion cattle worldwide with 50 million infected. 1/3 live in regions where bovine TB is controlled. 1/3 live in areas where disease is
widespread but prevalence unknown. 1/3 live in areas of high prevalence
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Discovery
Human vs Bovine Tuberculosis
Robert Koch’s Assumptions
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Koch’s Mistake- Mycobacterium bovis
1882, Robert Koch mistakenly stated that tubercle bacilli from humans and cattle were the same.
1901, Koch said that there were differences between the bacilli …but there was little danger of transmission from the bovine bacillus to man.
1905- Nobel Prize, “Bovine tuberculosis is not transmissible to man.”
1908, Stated that bovine infection could be transmitted to humans, but it would be “wrong to place the combat of bovine tuberculosis above that of human tuberculosis.”
Mycobacterium bovis
1865- Jean-Antoine Villemin- transfer of material from humans or cattle to rabbits.
Not a spontaneous disease
Tuberculosis infectious, the effect of “some contagious agent.”
Moved “consumption” to “tuberculosis”
1885- Auguste Chauveau- cattle-to-cattle transmission through ingestion. In man and cattle transmission through
consumption of milk and meat was possible.
1898- Theobald Smith distinguishes M. bovis from M. tuberculosis.
Smith
Villemin
Chauveau
Smith
Mycobacterium bovis
1901- John McFadyean and Royal Commission on Tuberculosis conducts research.
1911- Royal Commission on tuberculosis “Man must therefore be added to the
list of animals notably susceptible to bovine tubercle bacilli.”
Proposed test and slaughter.
McFadyean
Robert Koch
British, American, German Commissions formed.
Koch countered by McFadyean, Bang, Ravenel, Salmon, Lister, Virchow, Smith, Nocard.
Koch’s declarations emboldened special interest groups and political opposition to eradication.
Koch’s influence carried the discussion into the 1930s long after science had settled on the issue.
Not officially M. bovis until 1970
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Zoonotic Potential
As early as 1885 growing demand by public health officials for safe meat and milk.
M. bovis responsible for up to 25% of human tuberculosis, especially in children.
At the same time, 2/3 of all condemned US beef carcasses were for “tuberculous meat”.
Motivation for:
1) Mandatory pasteurization
2) Bovine TB eradication program
Why a bovine tuberculosis program?
Public Health Concerns 25% of human cases Easily transmitted through unpasteurized
milk Carcass condemnation
Most common cause for condemnation Rising rates of condemnation
Europe more severely affected showing where uncontrolled disease might lead
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Tuberculin: The Foundation for
an Eradication Campaign
Tuberculin Testing
1890- Koch develops tuberculin. Fails as treatment but veterinarians recognized the potential as a diagnostic aid.
Veterinarians (Gutmann and Bang) begin using it to diagnose bovine tuberculosis.
1892- Leonard Pearson (age 24) travels to Koch’s lab and brings tuberculin to Pennsylvania for first cattle skin tests.
Preventative Treatment
Koch’s lymph Paratoloid Tuberculin
Pearson
First tuberculin tests in USJersey cattle owned by Joseph Gillingham, Clairmont Farms, Villa Nova, PA- Trustee of University
Much attention and criticism Dr. Samuel Dixon- Academy of Natural Science in Philadelphia-
called Gillingham a fool and Pearson a dreamer Dr. W.L. Zuill- professor of veterinary surgery-headed a commission
to discredit tuberculin’s diagnostic properties SC administration and monitor body temperature 51 of 79 showed positive reactions.
Necropsies began on farm- continued at University
Producers, veterinarians, physicians, reporters
All 51 had gross lesions
Pearson to Gillingham- “..his sacrifice would come to be a blessing to every cattleman in the US.”
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Tuberculin Testing
Voluntary, at the farmer’s expense, no indemnity, carcasses buried.
Pearson’s plan- reactors appraised, postmortems under official supervision, meat salvaged.
Public education- on-farm necropsies drew large crowds.
Tuberculin Testing- Challenges
1892-1915: Testing methods varied
Subcutaneous
Intrapalpebral
Intradermal
No standard tuberculin
1908- human intradermal test used
1921- intradermal the official method used by the USDA Bureau of Animal Industry (BAI)
Rumors, fears, misconceptions
Inaccurate, harmful, milk shortages
Tuberculin Testing- Challenges
1925- Iowa Supreme Court
“Pitchfork Brigade”
Iowa “Cow War”
1931- Tipton IA, (Cedar County)
Hundreds of farmers opposed to testing
State Vets threatened
Governor Daniel Turner imposed martial law and called in the National Guard
Martial law lasted 2 months
Iowa “Cow War” Characters
William Butterbrodt- West Branch, IA “If there is no resistance there will be no trouble”
Arrested for stampeding cattle
Jake Lenker- Chased off officers and vets
Iowa Farmer’s Protective Association
1000 National Guard Troops and State Veterinarian
Norman Baker KTNT “The naked truth”
Cancer clinic, hypnotist, mail order artist
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Tuberculin Testing- Challenges
Interval to retest was unknown-desensitization
BAI recommendations to retest varied from 7 to 60 days
Potential for fraud
“cow massaging” and “plugging the test”
Inducing inflammation
Tuberculin Testing“Tuberculous Cattle Trust”
“Tuberculous Cattle Trust” James Dorsey of Gilberts, IL
20,000 cows/yr- ~50% tuberculous
“plugging the test”
Over 10-year period 10,000 new foci of infection across US, Canada and Mexico
1914- 12 states ban cattle from IL, unless tested by federal veterinarians
1915- Dorsey indicted, sentenced to 8 yrs Pardoned by Pres. Woodrow Wilson after 4 yrs.
Estimated responsible for thousands of human cases compared to “Typhoid Mary” responsible for 47 cases
Methods of Control- Controversy
Bang’s Method- control without slaughter Segregation in to 2 herds (reactors/non-reactors)
Herds housed and controlled separately
Calves removed at birth, colostrum/milk pasteurized
Slaughter from infected herd done under inspection
Monitor non-reactor herd
Popular in Europe, not in US
Costly, poor public acceptance
Test and Remove Indemnity, use of milk/meat, quarantine
Disposition of infected cattle - 1906 law- burning or burying diseased cattle
In reality infected portions trimmed or sent to far away plants for slaughter
Methods of Control- Controversy
Robert Von Ostertag- “Father of Veterinary Meat Inspection” Remove only animals with “open” lesions and
track visibly infected animals.
Manchester Plan (English)
Periodic testing of milk for bacilli and trace back to herd of origin.
French- relied on BCG vaccination.
Methods of Control- Lack of Uniformity
1904- 24 states with tuberculin test barriers
Variability in timing, stringency, etc.
Different approaches in different jurisdictions without consultation or cooperation
Need for uniformity
“It does not require any extended argument to convince us that the question to be discussed is necessity for some uniformity…let regulations be drawn up by the Bureau of Animal Industry”
S.H. Ward (MN State Vet)
US Bureau of Animal Industry
1883- Veterinary Division in USDA
1884- BAI created by congressional mandate.
“…prevent the exportation of diseased cattle, and to provide means for the suppression and extirpation of bovine pleuropneumonia and other contagious diseases.”
Daniel E. Salmon- 1st Director
Success with pleuropneumonia and FMD
BAI had power to condemn animals capable of spreading disease across state lines.
1893- First official skin test by Dr. E.C. Shroeder (15/34 reactions, 13/15 lesions)
1900- tuberculin testing required on all imported cattle
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Daniel E. Salmon
BAI- Noteworthy Research
Capable forward thinking scientists
Fred Kilborne, Cooper Curtice and Smith discovered (Babesia bigemina) cause of Texas Fever
Salmonella
Tuberculosis
1906 Pathology Division
Alonzo D. Melvin- Chief
Test and removal method
Herds in MD, VA, DC tested annually for 12 years. 17,000 tests, prevalence decreased 19% to 0.17%
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Smith Moore
Kilborne
Curtice
BAI- Noteworthy Research
Differentiation of human and bovine tubercle bacilli.
Differential virulence of the bovine and human bacilli in cattle.
Morphological and biochemical differences in cultures of human and bovine tubercle bacilli.
Transmissibility of bovine tubercle bacilli from cattle to swine.
Immunization of cattle with BCG.
Tuberculin potency testing.
Alternative routes of tuberculin administration.
Use of test and remove method of tuberculosis control.
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Moore
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Eradication Program States Led Way
Pennsylvania first state to establish program (voluntary) 2 M cattle, prevalence 2-3%
Some herds with 30% to 100% infected.
1895- PA State Livestock Sanitary Board formed $40,000/yr- TB, anthrax, glanders, rabies
Option of Test/Remove with Indemnity or Bang’s Method
PA manufactured tuberculin and anthrax vaccine
1898- mandatory testing 1899- 33,000 cattle tested
13.7% positive
$102,909 indemnity payments ($22.56/head)
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Eradication Program States Led Way
Massachusetts
Different laws passed in 1892, 1894, 1895, and 1896 led to confusion.
State Legislature passed a law restricting the use of tuberculin to confirmation of a diagnosis made by physical exam.
Prevented widespread and systematic testing.
Neighboring Maine refused cattle deemed TB-free by physical exam only.
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US Livestock Sanitary Association 1894- 8 state officials and the BAI recommended formation of
US Livestock Sanitary Association. 1897- 1st meeting in Ft. Worth, TX. State and territorial sanitary officials, veterinarians and 5
delegates named by Sec of Ag 1899- TB surpassed Texas Fever Resolution- TB is contagious and spreading, tuberculin was the
best means of diagnosis, states and BAI should authorize methods of control.
1904- Committee on Tuberculosis formed. Deal vigorously with TB, determine the reliability of tuberculin
test, determine methods of carcass disposal, define rules governing interstate movement of cattle.
Dr. Salmon pledged BAI would follow recommendations of Sanitary Association.
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Accredited Herds
Committee of 5 state and federal veterinarians and 5 representatives from livestock breeder associations.
1917- Unanimously adopted by Sanitary Association.
Accredited herds- Receive certificate valid for 1 yr
Certificate declared the herd had been TB free for at least 2 yrs
Cattle could be shipped interstate with no further testing.
Producers agreed to regular tuberculin testing and complete/accurate animal identification records.
1927: >96,000 accredited herds, comprising 1.5 M cattle, another 1.3 M having had one TB-free test.
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Accredited Herds
BAI- Director Melvin obtained $75,000 ($1.27M) from congress in 1917 to create the Tuberculosis Eradication Division.
Headed by John A. Kiernan (TN State Vet)
1917- 1st Uniform Methods and Rules approved.
60 days after approval- 1st herd accredited
US Soldiers Home in Washington, DC.
1918- Accredited Veterinarian Program
By end of 1920: >5500 accredited vets
1921- Eradication offices in 46 states.
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Accredited vets get to work
1901- >200,000 cattle tested
prevalence 3.9% to 100% depending on region.
1917 to 1941- 25M cattle tested.
prevalence decreased 4.9% to 0.3%.
1917- Henry A. Wallace
eradication of bovine TB is “an impossible undertaking”
1941- USDA Secretary of Ag- Claude R. Wickard
“the US is now practically free of bovine tuberculosis”
1941- Every county <0.5% prevalence
23-year cost- $200M taxpayer costs plus cost to farmers
Eradication Campaign 1917-1940
232 million tuberculin skin tests given. 3.8 million cattle destroyed
Cattle population average of 66.4 million
Every county in the US modified accredited (< 0.5% prevalence).
Economic benefits exceeded costs 10:1. Human M. bovis infection a rarity.
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1917-1959 individual animal testing (area testing).
Since 1959 focused on slaughter surveillance.
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Economic- Benefits
1917-1962: annual benefits $98.7 million
Net annual benefits $159 million
Decreased cattle lost from 100,000 to <30/yr
Saves $150M in replacement costs.
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Benefits- Public Health
Eradication plus pasteurization prevented >25,000 deaths.
Mortality from 150/100,000 in 1918 to <50/100,000 in 1942
<5/100,000 since introduction of streptomycin, isoniazid in the 1940’s and 1950s, <5/10,000 by 1980.
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Economic- Costs
1917-1992: actual cost $538M
255M federal, 283M state
Current program costs 3.5-4M/yr
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Obstacles to Bovine Tuberculosis Eradication
Importation of infected cattle Need for rapid, reliable and inexpensive test to be
used at border crossings. Inability to Test and Remove Cattle
Need for reliable, accurate diagnostic tests to remove infected cattle without whole herd depopulation.
Wildlife Reservoirs Need for vaccines for wildlife.
Safe vaccines Vaccine delivery systems
Need for vaccines for cattle. Infected vs Vaccinated
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Obstacles to Bovine Tuberculosis Eradication
Importation of infected cattle Need for rapid, reliable and inexpensive test to be
used at border crossings. Inability to Test and Remove Cattle
Need for reliable, accurate diagnostic tests to remove infected cattle without whole herd depopulation.
Wildlife Reservoirs Need for vaccines for wildlife.
Safe vaccines Vaccine delivery systems
Need for vaccines for cattle. Infected vs Vaccinated
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Questions?
