Wednesday, March 17, 2010

TB transmission - why we bother.

Every so often the comment comes up 'why bother'?

Why bother to test and slaughter cattle? - milk is pasteurised, meat inspected at slaughter and cooked, so why not just ignore tuberculosis? But although Defra are making a fine job of doing exactly that, it is of course a statutory requirement of EU and OIE trading, that tuberculosis be cleared from cattle and farmed deer herds, to protect human beings. And although badgers carry bTB in spades, (they must do or why is Defra spending a huge amount of taxpayer's cash telling cattle farmers how to avoid their animal's contact with them?) they do not "suffer" from this disease - so some would argue, let them live with it.

But to concentrate on sentinel tested and slaughtered cattle, the numbers, trading implications or otherwise - or even the maintenance reservoir of tuberculosis in badgers, is missing the point. We have mentioned spillover into camelids and other species several times (and will continue to do so) because that IS the point.
Exposure to tuberculosis, from whatever source is to be avoided.

The young vet in this Veterinary Record report was examining a dead cria (young alpaca) and was wearing protective gloves during the postmortem, although she did not wear gloves to euthanase the animal.
Six weeks after the postmortem examination, she noticed a tingling sensation in the tip of her right thumb, but no lesion was visible at that time. After a further three weeks, a painful, circular, pale lesion approximately 4 mm in diameter developed at the site. Despite initial antibiotic treatment with cefalexin and amoxicillin/clavulanic acid, the thumb lesion enlarged and assumed a verrucose appearance (Fig 3), with associated swelling
and pain in the elbow, lymphadenopathy of the trochlear and axillary nodes, and pyrexia. She was referred to North Devon District Hospital, where mycobacterial infection was suspected.
The lesion was tested, and samples sent for mycobacterial culture. M. bovis was identified with the strain being spoligotype SBO140, VLA 9, VNTR 6-5-5-4*-3-3.1.
.." 21 days after sampling, the skin lesion, which had regrown, was surgically debrided, and a six-month programme of anti-TB therapy was prescribed, comprising isoniazid, rifampicin and ethambutol. The symptoms resolved completely after this programme of therapy had started, and there has been no recurrence of mycobacterial disease at the time of writing, four years later.
The alpaca cria on which she performed a postmortem, was considered to be a possible source of infection.

We have showed you photos of the ravages of the disease on badgers, in the posting below. So for those who may not be up to speed with what tuberculosis does when it takes hold, here are some more photos - this time of some alpacas. The animals whose tuberculous lesions we show were euthanased either as a 'dangerous contact' to an animal showing clinical signs, or with the second photos, an X ray and blood test positive. Both had passed skin tests, the second animal 3 rounds over several months. Neither had clinical symptoms.

His body condition was good, giving no indication of what was lurking underneath his curly, white coat... but his lungs (first picture) at 20 percent, were barely functioning. He weighed over 100kg when euthanased.

The second alpaca also showed no symptoms but post mortem showed black spots on his trachea (pic. right) indicating open lesions right up to his throat. TB bacteria from these was available to other alpacas, his owner and any other mammal every time he exhaled, or spat, or coughed....

In the final picture, the lymph nodes on that second animal had been doing their job, hugely enlarged and sifting infection from his body. They are choc full of m.bovis 'cheese' - or in veterinary terms, "caseous abscessation".

This animal weighed 92 kg at the time of his death, but he had multiple tuberculous lesions throughout his body, including:
Abdominal cavity: Multifocal 2-20mm diameter creamy-white well encapsulated gritty focal lesions were present throughout the liver.

Alimentary system: Multifocal creamy-white well encapsulated gritty focal lesions, up to 10mm in diameter, were present at the junction of C2 and C3 stomachs and extended on to the proximal wall of C3 stomach and the distal wall of C2 stomach.

Respiratory system: Multifocal red/purple raised ovoid approximately 10 x 3mm plaques were present on the mucosa of the trachea, containing occasional gritty focal lesions. Multifocal 1-2mm diameter generally red-purple gritty focal lesions were present throughout the lung lobes. Two approximately 20mm diameter creamy white gritty focal lesions in the caudal left and right lung lobes also were seen.

Lymphoreticular system: Occasional up to 5mm diameter creamy-white well encapsulated gritty focal lesions were present within the spleen. The mediastinal, gastric, hepatic and bronchial lymph nodes were massively enlarged, often up to chicken egg size and effaced by caseous abscessation. The cervical lymph nodes were partially effaced by abscessation.

Urinary system: One approximately 1mm diameter creamy-white focal lesion was present in the right kidney cortex.

We are grateful for permission from the owner of these animals to publish the photos, and we offer thanks to the organisers of the recent " Alpaca TB Awareness " meetings, for raising the profile of this disease amongst their members, and for allowing these photos a wider audience.

The alpaca wearing blue, is the animal in the second and third postmortem pics - in happier times.

And he, his dead companions and the young vet described in the Vet. Record article above, as contracting tuberculosis while performing her job, is why we bother.


Anonymous said...

TB infections fell in 2009

March 19, 2010 | By Alistair Driver

INCIDENCE of bovine TB (bTB) in the national cattle herd fell during
2009, following the record levels seen in 2008, latest Defra figures show.

But concerns bTB is becoming more prevalent in species other than cattle
and badgers are heightened by the discovery of the disease in sheep and
wild boar.

Provisional statistics published on Wednesday (March 17) showed an 8.8
per cent decrease in the number of new TB incidents in cattle from 5,012
in 2008 to 4,572 in 2009.

With more herds tested in 2009, this equates to a provisional 14 per
cent decrease in the TB incidence rate ­ new incidents as a proportion
of tests on unrestricted herds.

Herds under restriction, however, due to a TB incident increased to
8,396 in 2009, from just under 8,000 in 2008, a figure that takes
long-term persistent outbreaks into account.

Details of the number of cattle slaughtered in 2009 are not yet available.

A further sign of the extent to which the disease is taking hold in
parts of the country emerged when a flock of Lleyn sheep in
Gloucestershire were placed under TB restriction.

Vets were alerted by chronic weight loss in 20 of 220 ewes and one ram.

Post-mortem findings in three of the six sheep were consistent with TB
and M. bovis spoligotype 10, the predominant strain in local cattle
herds and wildlife, was isolated. Lesions in these three sheep were
extensive, a letter in the Veterinary Record reports.

A Defra spokesman said the movement restrictions would only be lifted
when Animal Health was confident the flock is free from TB. He said M.
bovis in sheep was 'considered rare'.

The Department has also revealed 'lesions consistent with TB' have been
identified in a feral wild boar in the Ross-on-Wye area during
post-mortem examination.

Defra figures show there were more than 140 bTB cases identified in
individual animals other than cattle in 2009, including in 68 alpacas,
26 cats, 23 pigs and five sheep. The true numbers are almost certainly
much higher as there is no active surveillance in non-bovine species.

Defra said most other species 'generally act only as spill-over hosts'
from cattle and badgers with disease not sustained within populations
without an external source of infection.

National Sheep Association chief executive Peter Morris said cases in
sheep were not unexpected¹ and the industry was not required to take
additional actions.

Anonymous said...

More untagged cattle seized in Cork

ANOTHER 56 unidentified cattle have been seized in raids on farms in Co
Cork by Department of Agriculture and Garda teams, writes Sean MacConnell.

The seizure comes following the discovery and destruction of 70 similar
animals from a number of farms in the county in recent weeks.

None of the 56 animals seized in the latest raids by the Department of
Agriculture's special investigation unit, along with local department
officials and gardaĆ­, were tagged.

An investigation, which began six weeks ago, first recovered the 70
animals of varying ages from five farms in the county. These were taken
to a central location, DNA samples were taken, and they were then
slaughtered and their carcasses destroyed.

Last week, as the investigation continued, the 56 new untagged animals
were found on two farms and these were also destroyed after samples were

It is believed a gang operating in the area has been offering to buy
animals for a very low price from farmers who have failed to tag or
present animals for mandatory bovine TB or brucellosis tests.

Matthew said...

Anon 5.29.
Thanks for that. John Bourne is on record as saying sheep do not get TB. He was very positive about it too. It is disease of mammals, so given the amount of environmental contamination available, it would be odd if they did not.

Anon 5.30
Can't defend farmers who flout the rules. But you've answered your own comment. The untagged cattle were slaughtered. It happens in GB too, if untraced cattle are found. It doesn't mean to say it is widespread and none of our contributers, all of whom have had TB in their herds, fall into that category.

Dianne Summers said...

The 68 alpacas mentioned in the previous post were on culture. Not all are cultured. My TB Support group in alpacas have lost almost 200 all confirmed TB. One herd has lost 42 on her own.
I know we are a drop in the ocean compared to cattle - but lets get the numbers right PLEASE.

Anonymous said...

Hello Matthew - good to see you're keeping up the tradition of John Bourne rather than seeing something positive (INCIDENCE of bovine TB (bTB) in the national cattle herd fell during

Please don't feel that you have to answer every posting - you often choose miss the point anyway.

The salient point about unidentified (or mis-identified, swapped tags, etc)cattle is "if untraced cattle are found" - with the key word being IF.

EMR said...

Yes more care has to be be more cautious about keeping the disease at arms length.

Matthew said...

Hello Anon 9.57.

The salient point of this thread is the spillover of bTB to other species, particularly alpacas whose photos we posted - and why we should all be concerned.
Do keep up.

Anonymous said...

Matthew said...

"Hello Anon 9.57.

The salient point of this thread is the spillover of bTB to other species, particularly alpacas whose photos we posted - and why we should all be concerned."

OK Matthew that's fine to have your say on what is after all your blog, BUT

You then say:

"Do keep up."

Were you a school teacher in a previous life, or just trying to be slightly offensive?

The poster that you are 'digging' at referred to a different salient point. "The salient point about unidentified (or mis-identified, swapped tags, etc)cattle ."

But hey, lets not get any sensible discussion going here

Matthew said...

Anon 9.00
You wouldn't want to be there if we were to get 'slightly offensive'.

And we do get seriously p**ssed off with trying to explain to you that we (as in the contributers to this blog) are NOT in the habit of swapping eartags, moving cattle under restriction without licences, or any other implied breach of the cattle tracing regs. which seem to stand guard for all cattle breakdowns.

We cannot speak for the occasional bad apple, nor would we, but occasional they are.

But what about all the cage traps translocated? Damn stupid idea, to translocate disease, not that we are imlying that our readers would do that - of course.
Even Steve Harris squeaks "they are not supposed to do that" when the fragrant Pauline Kidner explains that she translocates mended badgers ans why she continues to do that..

But when all the 'i's have been dotted, 't's crossed, calves registered, movements logged, and the vet comes and finds every registered animal on his CTS / VETnet list is present and correct, 6 x a year instead of annually, and says (again) how sorry he is to condemn bloody good home bred cattle, we are sure you will understand the frustration of being told (again) (even by implication) that somehow it's all our fault.

Anonymous said...

Not following your drift Matthew -

"But what about all the cage traps translocated?"

Are you referring to DEFRA operatives reusing traps in different locations during the RBCT?

"Even Steve Harris squeaks "they are not supposed to do that" when the fragrant Pauline Kidner explains that she translocates mended badgers"

Are you referring to release of badgers after multiple testing as per the agreed protocol?

When/what did Steve Harris actually say (squeak)

Anonymous said...

"INCIDENCE of bovine TB (bTB) in the national cattle herd fell during

"we do get seriously p**ssed off with trying to explain to you that we (as in the contributers to this blog) are NOT in the habit of . . . . . "

TB - national issue

If all farms were run perfectly (like yours) you could speak for all, and be criticized on behalf of all.

Some of us are trying to discuss this NATIONAL issue, and are not attacking YOU.

Unfortunately, if you wish to trade in the national market, you are part of it despite the fact that your practices are (unusually) good for the industry - eg double ringfenced closed herd.

Anonymous said...

I trust you have a nice manly deep voice (not at all squeaky), and a rich manly aroma - not mask by any sweet fragrances.

If you wish to resort to silly digs like this - perhaps you should change your blog name to StinkyFarmer

Anonymous said...

Matthew said...
You wouldn't want to be there if we were to get 'slightly offensive'.

Silly comment - you don't know me, or just how slightly offensive I might be.

Matthew said...

We have 'binned' deliberately irritating, spiteful and pedantic comments once on this site.
For the moment, your Anonymous barbs stay, offering a measure of the calibre of the writer(s) contribution.
Don't push it.