TB in cattle

Re: TB in cattle

Hannah Wynne Richards — Fri, 06 May 2011 17:32:42 GMT

The Welsh Assembly Government want tohave a widespread badger cull in endemic areas-and will probably eventually succeed-I expect a fall in TB incidence in cattle, but if it doesn't fall to 1980s levels, I won't be surprised-as I keep saying-badgers are part of the problem-it would be totally unscientific to deny that, and badger culling will lessen the problem, so I'm in favour of a cull-it's just I think we shouldn't turn a blind eye to other possible sources of infection , just because they are politically awkward

Wynne

Re: TB in cattle

plantagenet — Fri, 06 May 2011 16:47:41 GMT

It doesn't really matter why there were fewer badgers, or rather why more were culled, but the fact remains they were and TB in cattle has risen with the numbers of badgers.

TB in badgers appears to be passed through fights and close contact (also fighting) As numbers of badgers increase, their health will deteriorate as will nutritional status, overcrowding and territorial fighting will increase. TB is a disease of weak, malnourished, overcrowded animals. Badgers undoubtedly have TB and the same TB as the infected cattle.

TB moves accross the country in a slow predictable spread, it seems not to cross geographical barriers - rivers, ridges, motorways - it does not follow prevailing wind, it does not follow cattle movements. The conclusion to me seems logical that it is a vector that moves in that way. And lo! there is an appropriate vector with TB: the badger.

Black and white to me!

In other countries there are different vectors, they cull them.

No one is suggesting wholesale slaughter of all our native badgers - sensible population management, yes, and pretty drastic initial culling in some areas.

If the vector were rats, the problem would be solved.

Re: TB in cattle

Hannah Wynne Richards — Fri, 06 May 2011 16:13:39 GMT

But what if the human TB didn't cause disease in cattle-merely an immune response which reacted to the MAMMALIAN tuberculin ? I'm not convinced that sewage sludge isn't part of the problem-it's one of the things that has altered since the 1950s, when bovine TB was nearly eradicated without a co-ordinated badger culling programme. I think badger culling in infected areas will definitely improve the situation,but I just don't think it's the complete answer

Wynne

Re: TB in cattle

Michael Woodhouse — Fri, 06 May 2011 15:58:26 GMT

[quote user="Hannah Wynne Richards"]But Micheal, a sizable % of culled reactors are found on PM not to have any lesions. Did these pick up human TB from sewage, and have an immune response, which is then detected on the antigen (tuberculin ) test ?[/quote]

If they had either kind of TB it would be found on PM. You have to remember that there will be some false positives with a test carried out on so many animals [and false negatives]. Also the possibility of Johne's cross reacting.

[quote user="Hannah Wynne Richards"]If DEFRA is so certain that human and bovine TB are different strains, then what is the scientific, or moral basis for making it a notifiable disease, and spending tax payers money eradicating it ?[/quote]

It remains zoonotic, although accounts for less than 1% of TB diagnoses in this country.

Re: TB in cattle

Hannah Wynne Richards — Fri, 06 May 2011 15:46:46 GMT

But Micheal, a sizable % of culled reactors are found on PM not to have any lesions. Did these pick up human TB from sewage, and have an immune response, which is then detected on the antigen (tuberculin ) test ? If DEFRA is so certain that human and bovine TB are different strains, then what is the scientific, or moral basis for making it a notifiable disease, and spending tax payers money eradicating it ? Don't say it's EEC policy, because that just shifts the scientific debate one level further . For that matter, why not make it illegal to spoil the taste of milk by pasteurising it before sale ? DEFRA won't stop trying to eradicate TB, or stop pasteurising milk, for the very good reason, they know the incidence of human TB will rocket. Before pasteurisation was introduced infected milk was a prime source of human infections. Many illegal immigrants come from countries where bovine TB is endemic, there is no pasteurisation,they are highly unlikely to appear on staticstics for human cases , or be typed, because they won't visit the doctor, as they don't want to be found out, but their s**t still goes into the drains

Wynne

Re: TB in cattle

Michael Woodhouse — Thu, 05 May 2011 23:28:36 GMT

[quote user="Hannah Wynne Richards"]Another theory is do we have a reverse zoonosis situation I've raised this with DEFRA veterinarians,who told me that people and cattle have different strains. What I don't understand is how ,if this is the case that it's possible for people to become infected by drinking unpasteurised TB infected milk ? If it can spread from cattle to people,then surely there must be cross infectivity between species ? [/quote]

Wynne, you must remember that cattle mainly get the Micobacterium bovis, and the main cause of cattle TB is Micobacterium tuberculosis. There is no doubt that people can get bTB and cattle can get human TB, but if the source was sewage spread on land then the M. tuberculosis would show up. All positive reactors are post mortemed and the TB typed. Different areas have different molecular fingerprints and it allows maps of different strains of M.bovis.

[quote user="Wren"]though I did get very mildly excited when I read the leaflet about the new SAM system. Sounds too good to be true![/quote]

Are you printing the lists for testing out from Vebus? I thought it looked similar.

[quote user="Wren"]This whole discussion pretty much typifies why I intend to get out of LA practice ASAP. It's a shame as I like the rest of the work but as the sole TB tester for our practice I am mentally drained by the issues and contradictions above.[/quote]

Wren - if that's the only reason then stick with it. I don't expect vets will do doing any TT testing after Christmas and DEFRA's tendering exercise takes off.

Re: TB in cattle

Wren — Thu, 05 May 2011 13:53:58 GMT

This whole discussion pretty much typifies why I intend to get out of LA practice ASAP. It's a shame as I like the rest of the work but as the sole TB tester for our practice I am mentally drained by the issues and contradictions above. We are in a 4 year testing parish and until one small outbreak last year I had done 10 years of testing day in, day out without even seeing an IR. Some cows get to the age of 7 before they are tested (home-bred, in-calf heifers at time of previous test) and inevitably some never get tested.

Apart from the issues of whether our current form of testing is effective it is a rotten job, especially when your clientele comprises mostly suckler herds. It is dangerous, cold, wet and probably next to useless on a four yearly basis. We are paid peanuts for the worst work (6 hours to test 32 cows on an upland moor springs to mind) and only rarely test anywhere where the set-up and staffing levels mean that throughput speed almost makes the payment worthwhile. I inevitably 'forget' to inform the RPA that I'm going as when they turn up to check tags at the same time the length of time required for the job can increase by 50% but the payment stays the same.

I'm probably replying to this post on a bad day - tired, grumpy and less than eloquent - but I think it's a poor job, a poorly thought out scheme and a poor way of trying to eradicate (or control?) the disease. Just ask David Archer about TB and Johnes!!

ps. though I did get very mildly excited when I read the leaflet about the new SAM system. Sounds too good to be true!

Re: TB in cattle

Hannah Wynne Richards — Thu, 05 May 2011 12:44:46 GMT

TB affects cattle and badgers and people. Therefore it makes sense to have a wider approach. Having said that the disease was almost erradicated in the 50s without formal badger culling,as no-one knew badgers were affected at that time. Badgers weren't a protected species,so some were killed by badger baiters,but nothing like 100%,and the killing was not related to TB incidence I have one theory which may be valid,but maybe not. The fall in TB incidence correlated with the change in the national herd from Shorthorns toFriesians, and recurrred when Friesians were replaced by Holsteins, so were Friesians inherantly more resistant than either Shorthorns, or Holsteins?-just a thought

Another theory is do we have a reverse zoonosis situation I've raised this with DEFRA veterinarians,who told me that people and cattle have different strains. What I don't understand is how ,if this is the case that it's possible for people to become infected by drinking unpasteurised TB infected milk ? If it can spread from cattle to people,then surely there must be cross infectivity between species ? The rise in cattle TB incidence alsocorrelates with an increased use of sewage sludge as an agricultural fertilser, and an influx of immigrants many of whom have come from countries in which human TB is endemic-again just a thought-and probably one which is opening a real political can of worms-as the water companies have to get rid of the stuff somehow-and there's 20% more of it than in the 50s-because there's 20% more people producing it

Badgers are undoubtedly part of the problem, and culling in endemic areas will undoubtedly improve the situation-it's just I'm not certain it's the whole answer

Wynne

Re: TB in cattle

Thomas Johnson — Wed, 27 Apr 2011 14:49:06 GMT

[quote user="Gerry Henry"]

Call me stupid but I didn't think Argentina has/had rainforest. Isn't that further north.

[/quote]

These people want to save it, so there must be some:

http://www.worldlandtrust.org/projects/misiones.htm

Re: TB in cattle

Gerry Henry — Wed, 27 Apr 2011 11:43:48 GMT

Call me stupid but I didn't think Argentina has/had rainforest. Isn't that further north.

Re: TB in cattle

plantagenet — Tue, 26 Apr 2011 22:39:04 GMT

[quote user="Gerry Henry"]If the farming industry can't get its act together[/quote]

If the farming industry were allowed to cull badgers they would.

Yep, we can ship everything in from everywhere - cut down the rain forest and grow beef, we'll all pay eventually!

Re: TB in cattle

Gerry Henry — Tue, 26 Apr 2011 17:21:03 GMT

[quote user="Michael Woodhouse"]

[quote user="Gerry Henry"]

If its not a zoonosis then let the industry deal with it or not as the case may be. FMD is exactly the same.

[/quote]

And then they can do as great a job as they did with sheep scab? Without the pressure coming down from the top a minority will spoil it for everyone.

[/quote]

Who cares. Why should the financial burden of eradication fall on the taxpayer. If the farming industry can't get its act together that's their problem; there's plenty of Argentinian beef, New Zealand lamb, French milk ...

Re: TB in cattle

plantagenet — Tue, 26 Apr 2011 16:01:22 GMT

[quote user="Michael Woodhouse"]the huge flaw with the Krebbs trial[/quote]

one of the huge flaws rather.

what really annoys me is the misrepresentation of the results ie 'culling spreads disease' instead of the more scientific conclusions about the perturbation effect.

culling needs to be done effciently and completely, I personally would like to see an immediate 'fire break' put in place and then culling out within badly infected areas.

The way that TB spreads can only be a wildlife vector, regardless of all the propaganda.

And where in this is a scrap of compassion for the badgers - death of TB with coupled starvation and overcrowding is not humane.

Sorry, off my soap box and back to evening surgery.

Re: TB in cattle

Julian Earl — Tue, 26 Apr 2011 14:41:02 GMT

[quote user="mariette asselbergs"]

"Culling badgers"is the bluntest and laziest possible "solution", only expected to contribute around 30% reduction in an infectious disease.

A hundred years ago Europeans in Africa tried to control/eradicate sleeping sickness by trying to cull all wildlife. Very convenient since they already liked to shoot game. Even in the 80s the European Union still tried to eradicate sleeping sickness (trypanossomiasis) by aerial spraying of whole countries. The futility of this sort of approach has now been realised.

An ecological approach to disease control is nowadays widely accepted, but not in the UK vet community apparently.

It is a myth that TB cannot be controlled without culling wildlife. In Europe wildlife control was not part of TB eradication. (Yes Europe has also badgers, and deer). [/quote]

Control measures for a vector-borne disease in Africa one hundred years ago is not necessarily apposite for TB here and now. The differences are many.

Re. control/eradication in Europe: do you have sources for stating that (a) culling was not required, and (b) indications that the disease was in the wildlife?

Thirdly, it is nonsense to suggest that ecology is not seen as important but that part of the TB question is at least in part a secondary aspect of the eradication vs control question. If eradication then the ecology will be temporarily altered until the status quo is re-found with healthy badgers; if control, the ecology continues as it is, with a number of unhealthy badgers and presumably other wildlife.

[quote user="mariette asselbergs"]

I do not disagree that TB in wildlife should be controlled, but I do disagree that culling badgers indiscriminately is the way to do it.

We need to use methods to detect infected sets and cull infected animals/sets. We need to stabilize and promote healthy sets. We should support the use of oral bait vaccination ASAP.

We should concentrate on creating barriers between infected badgers and cattle (AND VICE VERSA!) based on proper evidence about how, when and where transmission occurs.

And we can do far more to reduce the risk of transmission by undetected TB infected cattle.

By keeping all attention focused on badgers we do not do our farmers a good service, because it blurs the picture for them to see what they themselves can do to reduce risks.

Mariette

[/quote]

No real disagreement there, as those are all sensible suggestions being made already. There is an element of tunnel-vision with some farmers and badgers, true, but that does not mean that we should ignore their contribution either. Not if we wish to eradicate the disease.

Re: TB in cattle

Julian Earl — Tue, 26 Apr 2011 14:24:15 GMT

It is a zoonosis, although only a handful of percentage of cases are caused by bovine TB I believe.

Re: TB in cattle

Michael Woodhouse — Tue, 26 Apr 2011 13:20:40 GMT

[quote user="Gerry Henry"]

If its not a zoonosis then let the industry deal with it or not as the case may be. FMD is exactly the same.

[/quote]

And then they can do as great a job as they did with sheep scab? Without the pressure coming down from the top a minority will spoil it for everyone.

Re: TB in cattle

Gerry Henry — Tue, 26 Apr 2011 10:20:35 GMT

If its not a zoonosis then let the industry deal with it or not as the case may be. FMD is exactly the same.

Re: TB in cattle

mariette asselbergs — Mon, 25 Apr 2011 22:21:42 GMT

I am not familiar with the South, but where I work cattle on TB infected farms are still allowed to be turned out, grazing around badger sets and latrines is not fenced off, wheat and barley lie in heaps with totally open access for badgers, cattle are housed in sheds with easy access for badgers, cattle are fed in the field on the ground, or in accessible troughs which are not cleaned, mineral licks are provided in buckets or blocks accessible to badgers, nobody uses electric fence at night to deter badgers, very few farmers practice biosecurity measures when going to market or bringing in new stock; and do you know of any research into ways to manipulate badger behaviour? I don't.

I have read what is proposed, and attended the meetings. Culling is not aimed at infected sets or animals (which you might detect using surveying for signs of unhealthy badgers/sets, using soil sample PCRs or possibly train sniffer rats like the ones used in Tanzanian hospitals to detect TB in patients sputum samples). The objective of culling is mainly to reduce numbers of badgers. There was even discussion that by all means it should be avoided that culled badgers should be checked for TB because scientists might manipulate the data to show that many culled badgers might not have TB!

The vaccination trials were dumped last year after months of mobilising vets and farmers. Vaccination can now only be done by private initiative (read charities) and is made very costly: Even we as vets are not allowed to vaccinate badgers unless we are trained (£850), certified (£1500) and licensed (£2000 annually). Vaccination by injection is of course a costly exercise, but oral vaccination should be not too difficult to develop and easy to apply since badgers eat bait easily. So I hope for that to become available ASAP.

As for 4 yearly testing parishes: as shown in Wales last year: 4 year testing intervals does not mean that cattle there are TB free, it only means what it says: they have not been tested for 4 years. And cattle move out of these parishes without even a pre-movement test!

Where I work most breakdowns are on farms which constantly buy cattle; breakdown in various "closed" herds turned out to be due to anergic animals. And large farms down with TB have the problem that they never manage to test all cattle at the same time and that that reactors hang around for weeks on end. The biggest problem as I see it is that the test as it is done does not detect enough reactors. It is an awkward test (on the neck in the crush with the clamp in the way), there are no checks if vets follow the protocol properly, and the presence of Johne's disease masks bovine TB easily by causing big avian lumps. Not even talking about fraudulent eartag swapping.....

Re: TB in cattle

Michael Woodhouse — Mon, 25 Apr 2011 21:30:33 GMT

[quote user="mariette asselbergs"]We should concentrate on creating barriers between infected badgers and cattle (AND VICE VERSA!) based on proper evidence about how, when and where transmission occurs. [/quote]

What do you suggest? We are talking about a free living, burrowing animal here. House all the cows all year round in the South West? Separating them in real life cannot ever be practical or economically viable.

[quote user="mariette asselbergs"]I do not disagree that TB in wildlife should be controlled, but I do disagree that culling badgers indiscriminately is the way to do it.[/quote]

Have you read what is being proposed? Kill as many badgers as is humanely possible on infected blocks of land. This is proposed alongside vaccination. A far cry from all out war on badgers. Lets not forget this is a significant welfare issue in badgers!

[quote user="mariette asselbergs"]And we can do far more to reduce the risk of transmission by undetected TB infected cattle.[/quote]

Maybe so, but in this country the major spread of disease is in badly affected areas on the most frequent testing interval farms, not randomly appearing in 4 yearly testing parishes.

Re: TB in cattle

mariette asselbergs — Mon, 25 Apr 2011 20:50:31 GMT

"Culling badgers"is the bluntest and laziest possible "solution", only expected to contribute around 30% reduction in an infectious disease.

An ecological approach to disease control is nowadays widely accepted, but not in the UK vet community apparently.

It is a myth that TB cannot be controlled without culling wildlife. In Europe wildlife control was not part of TB eradication. (Yes Europe has also badgers, and deer).

I do not disagree that TB in wildlife should be controlled, but I do disagree that culling badgers indiscriminately is the way to do it.

We need to use methods to detect infected sets and cull infected animals/sets. We need to stabilize and promote healthy sets. We should support the use of oral bait vaccination ASAP.

We should concentrate on creating barriers between infected badgers and cattle (AND VICE VERSA!) based on proper evidence about how, when and where transmission occurs.

And we can do far more to reduce the risk of transmission by undetected TB infected cattle.

By keeping all attention focused on badgers we do not do our farmers a good service, because it blurs the picture for them to see what they themselves can do to reduce risks.

Mariette

Re: TB in cattle

Julian Earl — Mon, 25 Apr 2011 11:41:32 GMT

Mariette,

That may well all be valid and an accurate assessment of the flaws in TB testing of cattle, both pre-movement and otherwise. However, no-one is arguing that badger culling offers the complete solution to the TB problem. BCVA clearly state that other measures have to be in place as well - that is common sense. But it isthe fact that badgers are effectively ignored as a crucial part of the problem - so that no matter what other measures are taken a wildlife reservoir will persist - is what most cattle vets object to.

The key question is whether we - vets, the public, the government - are willing to accept TB in cattle as an on-going problem or whether we wish to eradicate the disease. If eradication is the chosen option, then testing, culling and badger control are essential and must be considerably more rigorous than they currently are. If we just wish to control the disease, then we can have a more "relaxed" control method - although clearly the measures in place are inadequate at the moment to control this spreading disease.

Re: TB in cattle

mariette asselbergs — Sun, 24 Apr 2011 23:20:16 GMT

Sorry I still have not understood how to properly join into a forum discussion. Hopefully this appears somewhere in the TB discussion.

I have been involved in TB control in Holland in the seventies and in Africa during many years. I have now worked in UK the last 6 years and sometimes feel exasperated by the badger TB discussion. Sure, badgers contribute something, but the way testing is done is so ineffective that the whole badger issue seems a total sideline to me. Where I used to work in TB control, cattle were only tested with bovine tuberculin, and a reactor was an increase over 2 mm. In UK where Johne's is rampant, the comparative test is used, and obviously many reactors are hidden by a big avian lump. For several years, where I worked in UK, reactors were not removed until 4., 5, often 8 weeks after been found. Yes the farmer was supposed to keep them in isolation. Is that possible or realistic on a farm? If it is not done are there any controls or consequences? We do premovement tests in UK, which are then valid for 60 days. Cattle are moved through markets all over the country during this time, and the farmer thinks they are TBfree because of a negative premovement test 60 days ago. There are 4 year testing parishes (parishes are in no way epidemiological units) with TB positive one year testing parishes around them. 4 year testing parishes are thought to beTB free, and cattle are not premovement tested. But they are even more dangerous because they have not been tested for years. There are TB confirmed breakdown farms who managed to avoid retesting for months, sometimes a year or more because Animal Health has no authority to really force them to test. There are lots of confusions of farms with several CPH numbers or animals under one CPH spread over many different locations. And private vets testing are never checked with respect to their ways of testing. In Holland we had to inform the State Vet Service beforehand where we would test and there were random checks on our clipping and measurements. There has been a much more rigorous approach in Wales the last year, but in England financial cuts seem to have resulted in even less rigour in testing and removement of reactors. For example calves under 6 weeks are no longer tested on TB farms. But farmers feed calves mastitis milk even though it is forbidden. Everybody knows, everybody advises them not to do it, and everybody knows that they do it. Clearly some calves become infected this way. It is against the background of all this, that the role of badgers should be seen. Nobody seems to address the issue of TBcattle infecting the wildlife, where this is the primary problem. (TB positive farms still can turn out their cattle). The only discussion about the badgers is about culling, whereas many farmers stock their feeds out in the open without any protection against contamination from wildlife access (not just TB, also toxoplasma, liverfluke, etc). Animals are fed in the field on the ground or given buckets of minerallicks which wildlife can access easily. When this results in problems, the answer is cull the wildlife.

So in short in my opinion the badger discussion is a red herring in most of the country, certainly as long as the testing system, biosecurity and animal husbandry are so ineffective in preventing/controling infectious diseases. (respiratory problems, Johne's, BVD, fluke, resistant parasites and bacteria, etc.)

Mariette

Re: TB in cattle

Mark Holmes — Fri, 22 Apr 2011 00:28:37 GMT

It does seem a bit of an emperors clothes issue really. What is the point of culling out cattle and spending millions on disease monitoring, control and compensation. Not to mention the heart ache and wastage of often very important rare breeds only to leave old broc running around the farm and between farms wheezing and coughing like an old diesel engine on Lambert and Butler. Even if the old chap isn't going to be a source of infection beyond his range he will infect further cattle other badgers on that and neighbouring farms. There is little point controlling one without the other.

Re: TB in cattle

Julian Earl — Thu, 21 Apr 2011 23:00:43 GMT

We must not be confused by movment controls and control of wildlife reservoirs. Here in Lincolnshire we are TB-free and TB will not arrive via flying badgers or any other silly means - it will only arrive if farmers continue to buy in suspect stock until eventually one gets through the tracing net and is not culled out. However, once that does happen, then it will infect the local wildlife and become established in the area. The two issues are separate and have different significances.

One other important fact: TB has never been eradicated in any country without culling of the the wildlife reservoir. In the USA it was raccoons I believe, andin Australia it was opossums, but culling is essential if we are to eradicate the problem. So do we intend to eradicate the disease or do we just want to control it? DEFRA consider that TB is not an important human health problem - we know because our local DVM or whatever they call them now told us so. That in itself suggests that eradication is not the official target and meaning that we are stuck with this never-ending dispute apart from anything else.

The same problem arose when sheep scab was enzootic - do we try and eradicate or control? Eradication was abandoned and look where we are now - widespread scab, resistance and poor welfare where it strikes. TB is set to go the same way in principle.

Re: TB in cattle

Simon Baker — Thu, 21 Apr 2011 08:08:45 GMT

It's odd. That graph does make a pretty strong argument for causation rather than mere correlation between the old badger control measures and TB control. Yet were those control measures really more ruthless than the Krebs trial, of which the main criticism seems to be that it was not ruthless enough? Isn't one of the arms of the current proposals to which farmers are objecting better control and testing around animal movements? I agree with "i am ed" and would be interested to lay a small bet that if we had a graph of average lifetime distance travelled by animals over the last 40 years we'd see a similar upward kick to that in TB incidence. We do already know there has been a huge increase in the movement of livestock in our lifetimes: that marked a big difference between the 1968 FMD outbreak and the one on 2001. As a rough rule of thumb, if farmers are objecting to better controls on animal movement I wod be very suspicious that they have become over-dependent on that free movement. For farmers, having the government permit and pay for a massive badger cull is a lot more palatable than making a big change to their business model. So, the graph of badger control vs TB culls is impressive, but I agree there may well be other factors that truly are causal especially animal movement.