Veterinary Times article on bTB

Re: Veterinary Times article on bTB

Michael Woodhouse — Sat, 08 Mar 2014 02:26:52 GMT

You also need to consider what is happening in Ireland. The badger cull has cost about £450 each and achieved a massive reduction in TB.

Badger culling need cost the government nothing, if badgers were classed as vermin and landowners could control them as they do foxes. Cruelty to badgers (baiting) need to remain a crime, obviously. Shooting them with high powered rifles is humane.

I can see vaccination maybe one component of TB control in badgers, but we can't say 1 badger vaccinated = 1 killed. I understand the vaccine does nothing if already infected and healthy vaccinated badgers can still get TB. It might help a little bit, but we do need to significantly reduce badger numbers. They are in plague proportions with no natural predators. Decimating the hedgehog and ground nesting birds.

I don't want to see them eradicated, just properly controlled. If that means a farmer is in a TB breakdown and chooses to eliminate badgers from his far it should be his choice.

Re: Veterinary Times article on bTB

mariette asselbergs — Fri, 07 Mar 2014 16:27:38 GMT

[quote user="Hannah Wynne Richards"]

Marriette. Are you and I the only members of the entire veterinary profession prepared to look at the issue of a human source in a scientific manner? Everyone else is simply accepting DEFRA propaganda.

Wynne

[/quote]

Agree with you Wynne.

TB in the UK is a highly politicised disease in my opinion.

I don't know if you saw the news that Wales, with Glossop's policies in the last 5 years, has now 25% less outbreaks and 33% less cattle slaughtered as TB reactors.

Wales did some very good things: Took a year of intensive testing of ALL farms, and found 100 farms which were so-called free (and on a 4 year testing scheme and no pre-movement tests) had TB breakdowns (reactors with visible or cultured lesions).

Then I think Wales has also been very much more rigorous in the movement controls. Since it has now also been proven that a few infected cattle will transmit TB through the shared airspace even to cattle in the same shed but separated by half open walls, it must be clear to scientific minded people that all the dragging of cattle through cattle markets all the time is one big source of T B contamination. Remember, the premovement test has a sensitivity of 80% (missed 1 out of 5 cases), and is valid for 60 days, during which animals can be moved from one market to another.

I personally know of markets which are held in the open air, weekly, in a field where the rest of the week cattle from a farm restricted because of a TB breakdown is allowed to graze!

I always tried to convince my farmers with vulnerable herds (pedigrees and all that) to keep newcomers isolated and do a private post movement test on them. Very few took this up, actually the only one was a Scotsman, he knew that Scotland requires a post movement test.

Wales is also the place where they vaccinate badgers instead of culling them. The cull has cost £3500 per dead badger, I can comfortably vaccinate them for £200 a vaccinated badger, as long as the farmer does some of the pre-feeding and baiting work.. Lets just quietly wait how the TB situation in Wales develops, and then maybe something can be learned.

Mariette

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Thu, 06 Mar 2014 15:22:44 GMT

I've been going on for years (including on this forum) saying that badgers,whilst part of the problem are far from being the whole problem. I've said for years there may be a genetic (breed ) component,and genetics have now been proven to be part of the problem (I told you so ) I just wish someone would take my hypothesis of sewgae sludge seriously.

Wynne

Re: Veterinary Times article on bTB

No Name — Thu, 06 Mar 2014 15:06:53 GMT

[quote user="Richard Carter"]

[quote user="Diana Kennedy"]cattle be producing an enhanced hypersensitivity reaction[/quote] the BTB ID test only measures an allergic reaction. It does not represent disease, only exposure. In any population some if not most will recover. In humans a positive skin test is a good thing - means you unlikely to get TB.

[/quote]

I am not sure a positive test in humans is a good thing. I had a mantoux test and was told if it was positive I'd be referred to hospital urgently for further testing/treatment. I believe it is possible for people to have "latent TB" which might cause disease in future. Just because you have been exposed to a disease doesn't mean you are immune to it or won't get disease. I believe in the UK m.bovis TB is most common in the over 50s where the disease has reactivated (probably from unpasteurised milk before we started to pasteurise it in the ~50s).

[quote user="Hannah Wynne Richards"]

Diana Exactly!

Cross-sensitivity to human TB

Wynne

[/quote]

I don't think you can necessarily extrapolate that to say it must be human TB - but I guess it's certainly a possibility. In any case, does it matter if it is m.tuberculosis rather than m. bovis? I assume both would cause similar clinical signs in both cattle and people and both are zoonotic. Could it be possible to be cross reacting with other types of mycobacteria? Interesting question to ponder....

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Thu, 06 Mar 2014 12:29:22 GMT

Diana Exactly!

Cross-sensitivity to human TB

Wynne

Re: Veterinary Times article on bTB

Richard Carter — Thu, 06 Mar 2014 11:43:29 GMT

Re: Veterinary Times article on bTB

No Name — Thu, 06 Mar 2014 11:35:05 GMT

[quote user="Hannah Wynne Richards"]

Micheal. There's an awful lot of cattle who fail the test, but (after slaughter) not only are there no visible lesions to culture, but they can't actually grow TB fromthe carcass. The bovine (mammalian) lump is bigger than the avian one. Why?

Wynne

[/quote]

Could it be possible that the cattle are infected but have not produced any visible signs yet in the lungs?

Or could the cattle be producing an enhanced hypersensitivity reaction for some other unknown reason? (genetic, cross reactivity to other organisms)

As for growing them in the lab, they are quite fastidious and if you aren't sampling from an area where cells are infected its not surprising nothing turns up. It doesn't necessarily mean there is nothing there (in the rest of the carcass).

What other solutions do we have? It is a shame we can't vaccinate cattle to tackle the disease (not that the BCG is that effective in humans but perhaps easier to do than culling or vaccinating badgers and better than having entirely susceptible herds). Apparently it is on the DEFRA's long term agenda to produce a DIVA vaccine and change legislation etc. but not for at least a number of decades...

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Thu, 06 Mar 2014 10:36:46 GMT

Interesting letter from David Stanley in this week's Veterinary Times. Advises pre-movement testing to be replaced by a total ban on movement of cattle from infected to non-infected counties.

Certainly something more than is currently being done is necessary if TB is to be eradicated again.

Wynne

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Thu, 06 Mar 2014 10:33:24 GMT

Not really. They tried to get rid of TB from the 1920s/30s onwards - for public health reasons, but got nowhere. There was zero government interest in agriculture until the 2nd World War, when U-boats nearly starved us. Google about Harry Steele-Bodger and the survey scheme.

Wynne

Re: Veterinary Times article on bTB

Richard Carter — Thu, 06 Mar 2014 10:18:27 GMT

I don't think bovine TB controls originated from a public health perspective - the main thrust was the appalling loss of productivity and mastitis. As mentioned pasteurisation and meat inspection pretty much remove a serious threat to public health.

The problem is political and economic - do you want cows (no disease and expensive from a government point of view) or do you drop the lot and encourage farmers to grow trees if they cannot sort it out locally (+1 for the badgers, cheaper) We obviously think cows are good, there are lots of other people not so sure and who may prefer a new school or upgrading of their local hospital.

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Thu, 06 Mar 2014 08:56:51 GMT

Wynne

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Thu, 06 Mar 2014 08:54:30 GMT

Wynne

Re: Veterinary Times article on bTB

Michael Woodhouse — Wed, 05 Mar 2014 23:01:43 GMT

[quote user="Hannah Wynne Richards"]Have some of the cows which fail the TB test, but have no visible lesions on PM cross-reacted to human TB?[/quote]

All TB reactors are cultured and the bacteria is speciated and genetically tested. There are clearly defined strains of TB in different areas.

Re: Veterinary Times article on bTB

mariette asselbergs — Wed, 05 Mar 2014 20:04:27 GMT

"The vast majority of TB in humans is due to M. tuberculosis transmitted between people, which as far as I am aware does not cause disease in cattle."

M tuberculosis does cause tb in cattle. I remember one case in Holland where a whole row of tied up dairy cattle caught TB from an old farmer who used to urinate in the feeding trough of the cattle in the evening (God knows why). He had kidney TB. A vet student then caught the TB from one of these cows who got uterus TB.

Another example was the TB circling between humans and cattle in Mozambique, where draught oxen where trained (subjected to the will of the owner), by spitting in their mouth. The people in those villages also drank unpasteurized fermented milk from the cows. A high percentage of the draught oxen where positiv e for tb with loads of lesions even though they did not show clinical decline. The people presented often with tb in the local health centre (sputum diagniosis).

(Sorry for disgusting details).

Mariette

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Wed, 05 Mar 2014 17:34:22 GMT

PS I think they've taken good care not to ask - because the answer would be politically embarrassing.

Wynne

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Wed, 05 Mar 2014 17:24:47 GMT

Nobody is aware, because nobody has asked.

Is there a correlation between the use of sewage sludge, and new TB breakdowns? We don't know, because nobody's asked.

Have some of the cows which fail the TB test, but have no visible lesions on PM cross-reacted to human TB? Since we know there's a cross-reaction between bovine and avian strains (that's the reason for the 2 intra-dermal injections ) then how do we know there isn't a cross-reaction between human and bovine strains? We don't know,because nobody's asked.

Wynne

Re: Veterinary Times article on bTB

Thomas Johnson — Wed, 05 Mar 2014 17:11:32 GMT

[quote user="Hannah Wynne Richards"]

It's either a zoonosis, or it isn't.

If it's a zoonosis,then people can get it from cattle, and also vice-versa. Cattle can get it from humans.

[/quote]

It is a zoonosis, but TB in humans due to M. bovis is rare because of pasteurisation, before that it was more common. The vast majority of TB in humans is due to M. tuberculosis transmitted between people, which as far as I am aware does not cause disease in cattle.

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Wed, 05 Mar 2014 17:03:57 GMT

It's either a zoonosis, or it isn't.

If it's a zoonosis,then people can get it from cattle, and also vice-versa. Cattle can get it from humans.

I've been poining this out for years.

If ( when I 1st raised this point ) DEFRA had put 1 more tick-box on their TB forms - "Have you spread sewage sludge on your farm since the last TB test?", the data would now be available to show whether or not sewage sludge actually causes an increased incidence of new herd failures.

If you don't ask the question,then you'll never get the answer.

Wynne

Re: Veterinary Times article on bTB

No Name — Wed, 05 Mar 2014 16:48:56 GMT

[quote user="macflea"]

can anybody answer this for me , why is there such a reluctance to bring in the blood test for the whole herd? is the patent not up , it eliminates operator error , poor facilities , one day test less stressful, ideal for wild beef cows etc. here in ireland the only time the ministry do the gamma interferon blood test is done is when a vet finds reactors , ie only reactors are blood tested and if they come up negative on the bloods the vet has to explain why he fail the animal in the first place? has happened to me . fair dues to ye for the culling badgers which i believe are a big part of the problem , here in ireland they are trying a new scheme ,its trying to cull the farmers instead of badgers , no farmers ,no cattle ,no tb hey presto tb eradicated

[/quote]

I believe the specificity (97%) is not high enough for routine screening with the gamma test (< comparative skin test), but it has higher sensitivity than the skin test.

Equally, the skin tests probably is a good test for seeing if a herd if tb positive but less so for individuals.

[quote user="Bob Russell"]

I do tend to think it is the culling of reactors that causes much of the farmers suffering. Is the prevention now worse than the disease?

Milk is pasteurised, meat should be cooked. Is bovine tb really the killer? Was it ever the big killer?

[/quote]

If you left reactors, they would eventually lead to clinical disease and it wouldn't be profitable to treat them with lengthy antibiotics for months on end (6-9months of antibiotics for humans with tb!). Nor could they enter the food chain if the lesions were systemically spread through the carcass. Have heard of reported cases in Scotland where they developed clinical signs within the 4yr testing period. Obviously if you had a herd where the majority of cows were showing clinical tb then it would be a massive financial blow to farmers if you did nothing to prevent and control it in the first place. Obviously, however, with a test that isn't 100% you will accept some health animals are slaughtered too.

Not all milk is pasteurised (soft cheeses) and the disease may pose a risk to those in contact with the animals. I saw quite a gruesome picture once of a vet's finger (cutaneous TB) who handled a cria who was later found to be infected with TB - although rare. Meat shouldn't be a concern if the carcass is inspected to look for signs of systemic spread. Yes, it probably was a big killer in the UK before pasteurisation (and antibiotics).

[quote user="Hannah Wynne Richards"]

I have 2 questions, which no-one has yet satisfactorily answered. The first is, if the strains are different, then how can DEFRA (or the EU) possibly justify spending taxpayers money on eradication. If they are truly different, it isn't a zoonosis - end of. Secondly, even if the strains are truly different, many farmers complain of repeated reactors, all of which have no visible lesions on PM. I know some farmers who've had repeated test failures, yet not a single case found with lesions. How many of these have cross-reacted to human TB (from sewage sludge )

[/quote]

Just because the strains are different doesn't mean they aren't zoonotic, and we know bTB is zoonotic (though pasteurisation has reduced the risk quite massively). It does seem like a massive amount of money is spent on a disease where the risk to humans is quite low!

Re: Veterinary Times article on bTB

Bob Russell — Wed, 05 Mar 2014 16:04:47 GMT

I do tend to think it is the culling of reactors that causes much of the farmers suffering. Is the prevention now worse than the disease?

Milk is pasteurised, meat should be cooked. Is bovine tb really the killer? Was it ever the big killer?

Human tb is a disease of poverty and immunosuppression made worse by resistance thanks to patient non-compliance.

Kill all the badgers if you can but pointless doing things by halves. As far as I can see it is only possible to do half a job and that does not seem to work!

Light blue touchpaper and retire to do evening surgery!

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Wed, 05 Mar 2014 15:16:27 GMT

Badgers are undoubedly part of the problem, just not the whole problem. All credit to Roslin for looking at other factors, one of which - genetics could tie in with the amazing correlation in low levels of bTB and Friesians.

Wynne

Re: Veterinary Times article on bTB

macflea — Wed, 05 Mar 2014 15:07:38 GMT

Re: Veterinary Times article on bTB

Hannah Wynne Richards — Wed, 05 Mar 2014 14:45:49 GMT

1 Badgers were much rarer, but far from an endangered species. Badger baiting would seem to me to be a perfect example of perturbation, which has been proven to increase bTB levels in cattle. They certainly weren't systematically culled.

2 Avian TB affects all avian species, so the demise of farmyard poultry shouldn't have that much effect - the avian TB in wild birds is still present. On the subject of cross-reactivity. DEFRAs official attitude is human and bovine strains are different. I have 2 questions, which no-one has yet satisfactorily answered. The first is, if the strains are different, then how can DEFRA (or the EU) possibly justify spending taxpayers money on eradication. If they are truly different, it isn't a zoonosis - end of. Secondly, even if the strains are truly different, many farmers complain of repeated reactors, all of which have no visible lesions on PM. I know some farmers who've had repeated test failures, yet not a single case found with lesions. How many of these have cross-reacted to human TB (from sewage sludge )

3 Agree with you on this one.

4 Agree with you on this one.

5 I'm not really sure of your point here.

6 Agree with you here. I've never denied badgers are part of the problem,just far from being the major problem. BTW badger baiters didn't seal sets either. DEFRA claim the cull should reduce TB breakdowns by 15%. I would agree that is probably a realistic figure, and better than nothing, but we need to look at the other factors which made the 1950s eradication close to 100% successful.

7 Major major difference. Sewage sludge wasn't used as a fertiliser in the 50s.

Wynne

Re: Veterinary Times article on bTB

Richard Carter — Wed, 05 Mar 2014 13:46:17 GMT

Other changes that probably have an effect

1.badgers were rare and persecuted as vermin, now common and protected. Other wildlife also TB positive incl deer

2. most people had farm yard poultry and avian tb was commonplace so badgers would have been eating avian tb earth worms before finding a bovis tb organism - we know from human tb that an intact immune system will develop a very good immune response on initial infection if you are exposed to your species 'natural' infection first before exposure to the unnatural or more virulent forms. However work on cross- reactivity between the various M.avium species has mixed results.

3. Movement of cattle now uncontrolled - an infected bovine can be across the country in hours and after fmd culling, mass movement took place.

4. Closed herd principles seems only to apply to certain people and common sense about new introductions, pre-movement testing and health examinations out the window.

5. BTB intradermal testing been tried to be used as an individual animal test rather than a herd test.

6. Contaminated badger sets not dealt with so new naive badgers move into very high levels of contamination and as M.bovis can live for years in soil off we go again.