Assistant State Veterinarian over Ruminant Programs Bovine TB Program Coordinator MDARD Overview Background of Saginaw TB infection Outcomes at infected farms Trace investigation outcomes Circle testing and outcomes ID: 706298
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Slide1
Bovine Tuberculosis
Dr. Rick SmithAssistant State Veterinarian over Ruminant ProgramsBovine TB Program CoordinatorMDARDSlide2
Overview
Background of Saginaw TB infectionOutcomes at infected farmsTrace investigation outcomesCircle testing and outcomesHow the Saginaw herd infection happened
Lessons learned
What about Michigan’s TB Free Status?
Questions & AnswersSlide3
Background
February 19 - cow discovered at slaughterFebruary 25 - Saginaw herd quarantinedFebruary 28
-
slaughter cow
bovine TB positive
March 12
- Michigan strain of bovine TBSlide4
Ante-Mortem Test Results
March 4-7 - herd TB tested 17% caudal fold response rate
13% gamma interferon - 6 mo. +Slide5
2013 Saginaw Co.
TB positive dairy herd
Gratiot & Midland Co.
TB positive
herds
Arenac
& Huron Co
.
TB positive
feedlots
2013
March 25
- Saginaw dairy
May 1
- Gratiot & Midland herds
September 5
-Arenac feedlot
2014
February 27
- Huron feedlot #1
April 3
-
Huron feedlot #2Slide6
Outcomes - Infected Herds
June 7 - Small freezer beef herd depopulated in Midland County.
June 19
- Small dairy beef herd depopulated in
Gratiot County.
August 8
- Saginaw dairy herd completed
depopulation.
February
3
- Arenac feedlot complete depopulation with assistance from law enforcement
Bay Port & Port Hope feedlots in process of depopulationSlide7
Trace Investigations Outcomes
State and Federal veterinarians followed 248 traces to 198 unique farms that were linked to the infected farms and feedlotsThree TB affected herds were found as a result of these investigations – Gratiot, Midland, Arenac herds mention on previous slides78
of the 198 herds needed to TB test -
17,209
head of cattleSlide8
Circle Testing
Public Act 466 - requires circle testing
Typically 10-mile circles
Three overlapping
10-mile circles - Saginaw, Gratiot, Midland
Feedlot circles - 3 miles - Arenac,
(2)
HuronSlide9
Circle Testing
All cattle herds in circle must be tested within 6 months, unless: Herd plan to test laterFeedlot agreement to only to sell to slaughter
Herds not under quarantine until the day the actual TB testing begins
Once the testing is completed the quarantine may be releasedSlide10
What to Test in Circle Test?
Cattle and bison 12 months of age and olderAll non-natural additionsGoats that are comingling with the cattle or bison that are 6 months of age and older
Captive cervids that are comingling with the cattle or bison that are 12 months of age and olderSlide11
2013 Circle Testing Outcomes
107
farms tested in Saginaw-Gratiot-Midland-Arenac County circles
11,438 cattle tested
No further disease discovered !Slide12
2014 Circle
Testing1st
Huron County circle test (Bay Port)
3
mile - 24 premises in database
March 31 - September 30
2
nd
Huron County circle (Port Hope
)
3 mile - 24 premises in database
May 6 - November 6Slide13
How Saginaw Herd Infection Happen
Genetic testing of TB found in Saginaw herd linked Saginaw herd’s infection to bovine TB found in wildlife (deer, raccoons, opossums) and cattle in NE Lower Peninsula’s Modified Accredited ZoneTo date all wildlife testing in Saginaw region has been negativeSlide14
How Saginaw Herd Infection Happen
Trace investigation found that Saginaw herd last purchased milking cows in mid-90sMarket records Three different source herds that had provided the Saginaw herd with bulls were TB tested -
6,085
head of cattle
all tested negativeSlide15
How Saginaw Herd Infection Happen
Most likely source of infection was from a cow purchased in mid-90s, perhaps from dispersal sale in TB zoneSimilar case found in November 1993 at Isabella County
dairy
through slaughter surveillance
Smith
et al
- JAVMA, August 1, 2013
one infected animal introduced into dairy herd
6 to 19.42 years to discover the infection through slaughter surveillanceSlide16
How Saginaw Herd Infection Happen
Multiple factors likely involved in causing the infection to spread through the herd during the summer of 2012Stress of heat and drought in summer of 2012Stress of calving
Spatial stress – tight quarters
Feeding unpasteurized milk to calves.Slide17
How Other
Herd Infections HappenGratiot
- infection introduced from feeding infected unpasteurized milk from Saginaw dairy
Midland
- infected animal originated from Saginaw dairy
Arenac
- infection introduced by feeding unpasteurized milk from Saginaw dairy at
G
ratiot farm in 2012
Huron County feedlots
- infected cattle from Saginaw herd purchasedSlide18
Lessons Learned
Important to identify all cattle moving off Michigan farms with RFID tagsBecause Saginaw farm’s 2012 bull calves were not identified with RFID tags it complicated the trace investigationNot feeding unpasteurized milk to calvesAt least two of the three other farms found with TB were infected by feeding unpasteurized milk to calvesSlide19
What About Michigan’s TB Free Status?Slide20
Questions
?