Bovine Tuberculosis

Question 1

What causes bovine TB?

Answer 1

Mycobacterium bovis
Chronic bacterial infection of cattle

Question 2

Significant of bTB

Answer 2

Zoonotic but not the primary cause of TB in people
* More of a social/economic problem than human health
Positive animals culled
Very expensive to farmers and government

Question 3

What is the 25 year eradication strategy?

Answer 3

2014
England split into 3 management zones
○ High risk area (HRA)
○ Edge area (EA)
○Low risk area (LRA)
General increased frequency of testing
Increased eligibility for cattle for statutory testing
Pre-movement testing requirements
Contiguous testing
Licensed badger culling and vaccination
Provision of biosecurity advice
Financial penalty for overdue testing

Question 4

What does the area determine?

Answer 4

○ How frequently they’re testing
○ What testing is used
○ How test is interpreted

Question 5

2018 review of 25 year scheme

Answer 5

○ Focus on biosecurity and increased industry ownership
○ Strategies to increase test sensitivity
Different tests
○ Research into cattle vaccines and tests
DIVA/bulk milk tests
○ Genetic resistance in cattle
Some breeds more resistant/susceptible
○ Risk based trading
Microchips
Mandatory post movement testing
Reduction in compensation paid to farmers

Question 6

2020 response

Answer 6

○ Increase test sensitivity/movement restrictions
○ Accelerate work on bTB cattle vaccine
○ Phase out intensive badger culling and increase badger vaccination
○ Incentivising uptake on effective biosecurity

Question 7

Testing methods

Answer 7

SICCT - Single Intradermal Cervical Comparative Test
Blood tests
Post-mortem inspection

Question 8

SICCT - Single Intradermal Cervical Comparative Test

Answer 8

Most common testing method
2 injection
* Avian and bovine tuberculin
Results:
* Clear
* Inconclusive
* Reactor

Highly specific - SpIn (low false +ves)
Lower sensitivity - SnOut (high false -ves)

Question 9

Blood Tests

Answer 9

IFNgamma testing used in addition to SICCT in some breakdown herds
Less specific - more false positives
More sensitive - less false negatives
Antibody test
Occasionally used as a third line test

Question 10

Post-mortem Inspection

Answer 10

All cattle are inspect PM in abattoir
* Reactors will have a more detailed inspection
* Approx 60% of skin test reactors have no visible lesions on PM

Question 11

Cattle vaccines

Answer 11

BCG vaccine going through marketing authorisation process
* Causes cattle to react to TB test
* DIVA test is being developed to allow vaccination and testing

Question 12

Badger vaccines

Answer 12

2010 BCG licensed for used in badgers
Reduces lesion development and shedding but won’t ‘cure’
Requires trapping of sufficient animals to have herd immunity
Oral vaccine in development

Question 13

Badger vaccines

Answer 13

2010 BCG licensed for used in badgers
Reduces lesion development and shedding but won’t ‘cure’
Requires trapping of sufficient animals to have herd immunity
Oral vaccine in development

Question 14

What biosecurity measures can farmers introduce?

Answer 14

Risk-based trading
Wildlife proofing
Environment improvement

Question 15

Risk-based trading

Answer 15

○ Pre-movement/post-movement testing
○ Use ibTB to assess TB risk in area
○ Isolate brought on animals

Question 16

Wildlife proofing

Answer 16

○ Gaps no more than 7.5cm wide/high
○ Secure feed storage areas
E.g. lids on bins/secure fencing
○ Dig fencing into the ground to prevent burrowing underneath
○ Raise feed troughs/mineral licks off the ground