Bovine TB question

Re: Bovine TB question

Neil Wheadon — Tue, 22 Oct 2013 20:32:46 GMT

Cats Again any evidence for feral cats on the farm catching it from the cows? Any confirmed cases in the cats, did you report this if there were? Feline TB is reportable and AHVLA do investigate these. A few years ago I did case number 27 in Gloucester, non of the previous cases were farm cats. In this case it was a cat from a housing estate that had confirmed TB. Of interest was the same spoligotype as the nearest outbreak. The outbreak was in a shed of fattening cattle so no milk there. TB has been found in every species looked at so I expect cat caught mouse with TB. TB is one of the most researched conditions in this country, there are at least 70 studies going on all the time, I placed squash against a guy doing a pHD looking at spoligotypes in the ground. The depth of knowledge is extensive and I wish the original poster well but do wonder with the questions asked the depth of work that will be done. West Country news looked back at the Thornbury trial in 1972, all badgers removed, no TB in cattle for many years. Is it that simple? In my opinion yes Maybe cats, human sewage do play a part, but there is no proof and may explain the odd outbreak but not 650 Neil

Re: Bovine TB question

Hannah Wynne Richards — Tue, 22 Oct 2013 16:50:52 GMT

YES!!!!!!!!!!!!!!!!!!!!

Wynne

Re: Bovine TB question

mariette asselbergs — Tue, 22 Oct 2013 13:22:55 GMT

Ha Wynne, we found something to agree on! " src="http://www.vetsurgeon.org/emoticons/v2/Very_happy_smiley.png" />

Mariette

Re: Bovine TB question

Hannah Wynne Richards — Tue, 22 Oct 2013 13:06:58 GMT

Thank goodness someone other than me thinks the problem is multifactorial. Badgers are part of the problem,but not the whole problem

Wynne

Re: Bovine TB question

mariette asselbergs — Mon, 21 Oct 2013 22:44:35 GMT

2) Regarding semi-feral cats, are you suggesting they act as a reservoir for the cows? Do you have any evidence for this as anything other than an unusual problem? So far as I am aware, the vast majority of tuberculosis lesions found at post mortem are in the respiratory tract rather than in the udder as used to be the case, so infection via milk is unlikely. (David Shepherd)

Yes I have tested endlessly on dairy farms with more than 30 semiferal cats who made a queue in the morning to drink from the buckets of mastitis milk which was later given to the calves. They also drank this milk when left over in the troughs. They then contaminated the feeding troughs with their saliva, faeces and urine. The farm had calves with visible lesions at age 3 months. And it only tales one cow with TB mastitis to infect a whole batch of calves if milk is mixed together. You probably know that this is how a whole batch of calves exported to Holland from UK was found to have TB. . TB mastitis is not rare as you think, TB infected milk was the greatest source of infection and the greatest cause of mortality in farm children in Holland before pasteurization.

I agree with you that the always quoted sensitivity and specificity data are difficult to base on evidence. I have never found a proper source for them. And it is interesting to hear that in tens of thousands of cattle tested you would never find a reactor. But I have found numerous hidden reactors (false negatives) which never gave the slightest reaction to the tuberculinisation. They were found riddled with TB either in a slaughterhouse or when I did post mortems. So I am convinced that anergic animals are one horrible source of constant infection of herds, and badgers in the area. Unfortunately farmers (and many vets?) never tend to think about the problem of their infected cattle infecting the wildlife, they only think of the other way around. Dung of infected herds is spread over land, milk if not fed to calves is mixed with dung. Reactors and Inconclusive animals are often not isolated (or should I say almost never?). It has taken sometimes 5 or 6 weeks to pick up reactors for slaughtering. Breakdown farms have no restrictions on where they can graze their cattle. In the most surreal case cattle from a breakdown herd were happily grazing and shitting on land where weekly sheepmarkets were/are held!.

And as far as biosecurity goes: Heaps of loose grain feed for cattle completely unprotected creates an enormous risk, and the excuse of it being cumbersome and expensive to lock it up safely is feeble in my mind! Brand new sheds are build on farms where there are badger setts on the farm, with the cattle feeding with their heads outside, silage thrown in front of them, very conveniently with the tractor, but totally unprotected and open to any wildlife joining in the feast! How difficult or even expensive would it have been to make sure there was a wildlife proof fence around this feeding area.

I had one farmer following our advise when he complained that he always went clear in spring and down again after the grazing season. How did he feed his cattle in the field: by throwing the food on the ground. We advised him to use troughs, only feed in the morning, and at 17.00 turn the troughs upside down so no badgers could climb in them. He hasn't been down since which is the last 5 years.

If you are familiar with the "biosecurity" discipline around human TB patients in the community in Africa, (and formerly her in Europe), then you look at the practices here on farms and are not surprised that the disease is not being brought under control. And in my opinion the badger story is what distracts everybody from all the other leaks and vulnerable situations there are in the system.

One more point "as far as you are aware" the vast majority of reactors have infections in the respiratory system on post mortem. I have seen these post mortems and unfortunately, the digestive tract and the mammary gland are simply very rarely looked at. And "post mortem" is a big word for mostly looking at lymphnodes but not salami slicing them for fear of opening lesions in an environment with no boiling water for desinfection......

O dear I should not let myself into these arguments and stories, I have left this side of the profession and look back in empathy with the farmers and frustration of the haphazardness and politics ridden ways in which the whole TB problem was dealt with.

Wales seems to me the most promising place at the moment and I hope they will provide the evidence for a successful campaign.

Mariette

Re: Bovine TB question

Neil Wheadon — Fri, 18 Oct 2013 22:57:21 GMT

[quote user="mariette asselbergs"]They keep infecting their badgers[/quote]

Any evidence of this? The number of open cases in cattle are very few. The language used suggests this happens commonly.

[quote user="mariette asselbergs"]If testing is done rigorously, then reactors tend to become rare after a few tests. If it is done in a bit relaxed way, then reactors will keep popping up, because the sensitivity of the test is only at best 80 %, meaning of each 5 cattle with TB you miss one.[/quote]

Working for AHVLA, I was frequently amazed by the integrity of many OV's testing what is in effect their clients cattle. Failing a single cow in a 400 herd dairy farm with a +5 reading meaning everything was shut up takes some doing.

In an area where the wildlife is an issue then regardless of the testing, reactors don't decrease dramatically. What does decrease dramatically are the cattle in that particular epidaemeological group either due to reacting and removal, or the farmer moving them somewhere else. I dealt with a number of cases where the group affected were the heifers out to grass, in one case the farmer lost 73 out of 76 over about 6 tests and in another similar devastating losses meant that even after 8 years the farm still hadn't recovered.

Neil

Re: Bovine TB question

David Shepherd — Fri, 18 Oct 2013 14:57:00 GMT

[quote user="mariette asselbergs"]

1) AHVLA is your source of info on these sort of statistics. However they tend to suffer from severe data protectionitis so I don't know if they'll let you into anything.

2) in TB areas. like South West, Wales, West Midlands, you will see reactors every 60 day test when they trade all the time, or dairy farms which have lots of semi feral cats around drinking the milk ready to feed the calves, and/or who feed mastitis milk to calves.

3) Very large herds will all the time have one or two reactors, since the specificity of the test is 95-99%. Meaning that out of 100 cattle being negative there will be 1 false positive.

4 Herds that have Johne's (and worse if they vaccinate), are very difficult to clean of TB, because the bovine reaction is so overshadowed by the avian lump.

5 Herds in notorious TB areas, with badgers, who have no proper biosecurity with respect to their food storage, will also tend to keep reactors. They keep infecting their badgers, and some badgers will keep infecting the cattle food.

If testing is done rigorously, then reactors tend to become rare after a few tests. If it is done in a bit relaxed way, then reactors will keep popping up, because the sensitivity of the test is only at best 80 %, meaning of each 5 cattle with TB you miss one.

Good luck.

If I may suggest something: If you have funding for research then try to evaluate the Wales vaccination effort?

Mariette

[/quote]

Hi Mariette, some interesting points you make here;

1) AHVLA are increasingly secretive and uncooperative especially with regard to TB. It is extremely difficult to get any information out of them about herds under the care of our practice, let alone third party access to information. As I have said elsewhere, they seem to see themselves these days as a separate profession, only loosely governed by RCVS guidelines about professional responsibilities, and ready to hide behind spurious data protection concerns.

3) Regarding the sensitivity and specificity of the SICCT; I have never been able to pin down the scientific basis for the various figures quoted. However, like Michael above, for many years we tested tens of thousands of cattle without finding a reactor; I do not believe this was because we were not doing the test properly. I do not know of any evidence that 'very large herds will all the time have one or two reactors'. Now that TB is creeping into our area we see more reactors, although in answer to the OP our experience is that herds will generally go clear after two or three tests.

5) Your comments about biosecurity and badgers are rather tendentious. There are many recorded instances of infection of cattle outside on grazing where freedom from badger contact is impossible to achieve, and infection is not due to contaminated feed. Keeping badgers away from food sources in buildings is also not without difficulty and expense.

To the OP: good luck with your research; as much independent research in this area as possible would be a good thing.

Regards, David

Re: Bovine TB question

vs0u — Fri, 18 Oct 2013 12:58:57 GMT

It's all going through the university ethics/health and safety etc - I'm also working with supervisors who've plenty of experience of the legal aspects of this sort of work. I've also read hundreds of papers on the subject. I'm really just after some informal opinions of what the situation actually is to help with planning the practicalities...sometimes published literature and official stats don't quite give all the details needed!

Thanks everyone!

Re: Bovine TB question

Sylvia Wilson — Fri, 18 Oct 2013 11:03:12 GMT

[quote user="Anthony Dennison"]

[quote user="Sylvia Wilson"]In the North, it is a rarity. [/quote]

Think it's becoming a problem in the North West actually, LLM and the farm vets at my practice have held farmers meetings about the issue and how to prevent it getting worse.

[/quote]

Sorry, should have said "parts of the North".

Alison, you really must speak to your local Animal Health Office vets. Although it has been a while since I worked for Animal Health, I am pretty sure there are legal implications if you want to sample reactors and VOs will have more experienceof the gamma interferon test. than any one practice can.

Re: Bovine TB question

vs0u — Fri, 18 Oct 2013 09:21:28 GMT

Many thanks for the comments. I will be aiming for areas where there are likely to be lots of reactors, and it sounds as if, in particular areas, it will be possible to get plenty of reactors from one herd. I was planning to sample every animal in a number of herds (3-6?) every 2 months for a year and would be needing about 150 reactors in total.

Interesting idea about the badger vaccination Mariette. I will have a think about it. (I read your letter in the guardian last weekend!). Also an interesting point about Johne's - I wasn't aware of that. I'll also find out what info can be got from AHVLA.

Does anyone have any views on the gamma interferon test?

Thanks

Alison

Re: Bovine TB question

mariette asselbergs — Thu, 17 Oct 2013 16:07:49 GMT

1) AHVLA is your source of info on these sort of statistics. However they tend to suffer from severe data protectionitis so I don't know if they'll let you into anything.

3) Very large herds will all the time have one or two reactors, since the specificity of the test is 95-99%. Meaning that out of 100 cattle being negative there will be 1 false positive.

4 Herds that have Johne's (and worse if they vaccinate), are very difficult to clean of TB, because the bovine reaction is so overshadowed by the avian lump.

Good luck.

If I may suggest something: If you have funding for research then try to evaluate the Wales vaccination effort?

Mariette

Re: Bovine TB question

Anthony Dennison — Thu, 17 Oct 2013 14:29:04 GMT

[quote user="Sylvia Wilson"]In the North, it is a rarity. [/quote]

Think it's becoming a problem in the North West actually, LLM and the farm vets at my practice have held farmers meetings about the issue and how to prevent it getting worse.

Re: Bovine TB question

Sylvia Wilson — Thu, 17 Oct 2013 10:44:46 GMT

Entirely agree with both of the above. It depends entirely where in the country you are. In the South-West, you can see many reactors at every test. In the North, it is a rarity.

Have you approached your local AHVLA vets? They will be in the best position to advise you on the local position or to point you at an area that will give you the number of cases you need for your project.

Sylvia

Re: Bovine TB question

Busybee — Wed, 16 Oct 2013 22:12:10 GMT

You'll get a huge variation in experiences on here!

I've been TB testing for just over 2 years, working in the Worcestershire/Gloucestershire area. We are 'officially' on yearly testing but I would say well over 50% of our farms are currently on more regular testing due to having had TB breakdowns.

Our worst farms will get reactors or IRs every 60 days; number of reactors can vary - the worst one this year had 27 reactors out of 55 tested in one test - but more commonly, it would be roughly up to 10% reactors or IRs.

Rarely (very rarely), herds will continually go clear and just remain on yearly testing.

Advice for your project - look at farms in all testing areas, the numbers of reactors will vary massively depending on where in the country you look.

Re: Bovine TB question

Michael Woodhouse — Wed, 16 Oct 2013 21:57:00 GMT

Tested thousands of cattle. Never had a reactor. Had one cow killed as went IR twice. Had to ring Leeds to check what to do