TB Flashcards
Which form of TB used to be significant?
Mastitis
Which other system is invovled as well the pulmonary disease?
Draining lymph nodes
How is TB transmitted?
Nasal and aerosol
What is gold-standard for TB diagnosis?
CUlture
What’s the problem with culture?
Insensitive
What’s the problem with antibody tests for M bovis?
Poor sensitivity
Which species if the specific immune response against in diagnosis or surveillance?
M bovis
Which species are used in SICCT?
M bovis and M avium
After how long do you read a TB test?
72 hours
What kind of immunity do you see in SICCT?
Cell-mediated
What is the sensitivity and specificity of SICCT like?
High specificity, low sensitivity
How does Bovigam work?
IFN-gamma ELISA to measure the total amount
What’s the problem with Bovigam?
Does have higher sensitivity but lower specificity so more false reactions and can’t use it to screen herds
Which species will extended pasteurisation (15-25 seconds) work against?
M paratuberculosis
Who is responsible for slaughterhouse surveillance?
FSA
Who does the compulsory TB testing?
Private vets paid and managed by the government
How often is TB testing done?
1-4 years
What happened to TB testing in 2001?
Reduced testing by 60% and disease prevalence doubled and has not really reduced
Which part of the country are the epidemics usually?
Southwest
What are the serotypes of epidemics like?
Different and locally contained
What do homerange maps show?
Where each genotype is
Why do slaughterhouse cases have lungs affected more than reactors?
More time for disease to develop
What are TB areas divided into?
High, edge and low risk areas
How often is TB testing in Cheshire?
6 months
What happens if TB tests are failed?
Can’t move animals unless to finisher units or slaughterhouses
What must happen before the failed tests can go to slaughter?
Failed test must be confirmed by repeating it - called “breakdown”
What happens if the failed test is not confirmed?
Goes to follow-up
What will happen to most breakdowns?
Likely to recover
When is the TB risk largest?
If the farmer has had it before
What % of infected herds have had breakdown in previous 3 years?
50%
Why might having a PI not lead to breakdown?
High turnover rates
How many farms may have a PI?
20%
What is most TB recurrence due to?
Re-introduction
What is herd prevalence in annual testing areas?
16-18%
What is the evidence for badgers?
Ideal host, 6% badgers infected where TB was a problem but 0.75% elsewhere, experimental transmission shown, other species show no spread, badgers are the only infected spcies, 100% match of DNA types in cattle and badger cases
What did the Thornberry study show?
If badgers culled for 5 years, no TB in cattle for 10 years
How is badger culling different in Ireland compared to UK?
UK has lower badger density, different ecology, natural boundary
What can all breakdown be traced to in Scotland?
Transmission between cattle
What kind of vaccine is the BCG vaccination?
Attenuated M bovis
What is efficacy of vaccination compared to tuberculin testing?
Less
How does vaccination affect the skin test?
Sensitizes, even 20% reactivity at 12 months
What is protection like 24 months after vaccination?
None
Why can you not vaccinate alongside test and slaughter?
There are DIVA tests but none specific or sensitive enough
What is the problem with the badger vaccine?
Expensive and logistically difficult, and not shown to affect cattle rates
What is the 25 year TB strategy?
1/4 yearly SICCT, slaughterhouse surveillance, follow up 6/12 month tests, pre-movement testing, unpasterised milk producers must test more often, gamma-IFN in low-risk areas
