Johnes in sheep flock

[scholland]

Wheelbarrow test is bad on so many levels. Cruel if the sheep is affected (some authors believe a positive animal should be immediately euthanased). Crap sensitivity. Can get false positives (animals in terminal Johne's disease have low blood protein and they can also get fluid in their lungs and give a false positive). Stressful if nothing else.

Screening in the live animal for OPA is by ultrasound of the lungs. I doubt we will ever have a good blood test.

Moredun and biobest are working on a pcr {i think }test done on nasal swabs
Trial work underway now i think.

 

[bovine]

Moredun and biobest are working on a pcr {i think }test done on nasal swabs
Trial work underway now i think.

Yes. Typical cost of a PCR is ~£30. I hear the test only identified less than half of affected animals in trials.

OPA doesn't produce antibodies that we can measure - like we do for a lot of diseases.

I just don't see the value myself.

 

[Danllan]

The problem with the system suggested by @bovine is (at least) two headed: 1) People will not have PMs done - or not have them done very quickly, that way confusing evidence as decay sets in 'Oh I called you as soon as I could...' and 2) Costs will rocket - although this could be mitigated by it being universal, so no competitive commercial advantage would be lost if all play fair...

However, long term, the ethical and practical advantages to the national flock would be immense and particularly for export. I like the idea and think it bears serious consideration as to how it could be practicably implemented. I wonder if a bit of joint strategic thinking and campaigning by the RCVS and NFU could see post EU money being sensibly spent... who knows or dares to wonder? Following that we might even see a sane program in re' BTB .

Edit to add: we have 'free' BTB tests, why not 'free' ovine PMs?

 

[bovine]

Eg:

http://www.ncbi.nlm.nih.gov/pubmed/19931475

Basically a sensitivity of 28% means if you test 100 positive animals you find 28 of them (and miss 72).

The specificity is good at 99% - so for every 100 negative animals tested only one of them will have the disease