Sunday, March 21, 2010

Baaaaa - more sheep

Hard on the heels of our posting below, comes the story this week of a flock of Lleyn sheep, with several 'bovine' TB casualties.
Vets were alerted by chronic weight loss in 20 of 220 ewes and one ram. Postmortem 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 subsequently isolated. Lesions in these three sheep were ‘extensive’, a letter in the Veterinary Record reports.
Farmers Guardian has the story which concerns a farm in Gloucestershire.

Defra's 'other species' TB statistics show 9 sheep samples under culture surveillance for 2009, and for 2005 a couple of positive samples. We told the tale of one of those positives here with Defra contacting farmers who had consigned sheep to Worcester market during late 2005, but who also farmed cattle. As the sheep sample proved positive, farmers who fell into that category were asked to test their cattle.

The tables published by Defra are by no means complete, up to date or accurate.
Although they show 144 positive samples at the time of publishing, that is the number of samples presented to VLA for culture. For camelids, if a herd is heavily infected, we understand that cash is not wasted sampling after the first couple are submitted. Thus the figures for alpaca deaths, personally communicated to vets leading the Alpacac TB Awareness roadshows, are in excess of 140, with some herds losing all their animals. Although veterinary postmortems confirm lesions which indicate TB, Defra has yet to acknowledge these deaths in their stats page - or anywhere else that we are aware of.

432 samples of species other than cattle were sent for culture surveillance during 2009, but many of the later results will not have been posted yet as these tables are compiled quarterly. Of the positives to date, 23 pigs, 26 cats and 68 alpaca make up the bulk of the culture-sample confirmed, 'bovine' TB casualties in 2009.

EDIT addition:
The veterinary press this week has published the story of TB in the Lleyn sheep, but added a cautionary wakeup call to all veterinary practitioners, advising not to confuse CLA with TB lesions in sheep:
Clinical signs and postmortem findings of TB in sheep may resemble lesions of visceral CLA. Failure to demonstrate serological or bacteriological evidence in cases of suspect CLA should trigger a suspicion of possible TB. Colleagues are reminded that suspect cases of TB detected in farm animals are notifiable to Animal Health. The small number of previous incidents of M bovis infection in sheep in Great Britain have been incidental findings at slaughter or at postmortem examination, but have not been associated with clinical signs. The VLA plans to provide more details of this incident in the near future.

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.

Wednesday, March 03, 2010

Air brushing

This posting contains images which should cause distress.

Four years ago, almost to the day, our co-editor blasted the RSPCA and the badger groups with this posting after their collective 'airbrushing' of the effect of tuberculosis on their chosen species.

If you remember, the RSPCA came up with the witheringly simplistic phraseology, that in the latter stages of the tuberculosis, badgers may experience 'a slight wheeziness'.
This was to support the Badger Trust's 'Back off Badgers' campaign.

A dose of Venos, two paracetamol and an (organic) carrot then?

Now much as we hate to burst this cosy bubble - and we too would like all badgers to mirror the one at the top of this posting - too many with tuberculosis, end up like these pics which we list below. All were taken at, or prior to, postmortems which showed them to have generalised, highly infectious and often terminal tuberculosis.

Of badgers taken in Ministry removals 1987 - 97, the area of Broadway in Worcs., came out top of the pile, with over 70 per cent of its badgers showing tuberculous lesions at postmortems.

Tuberculosis is not like a sniffle or a common cold. And although badgers can and do live with the disease, sometimes for years, intermittently shedding copious amounts of bacteria, eventually, this is their end, often after fierce fights.

They maybe diseased and excreting bacteria for 1 - 3 years, but once tuberculosis becomes generalised, they are in a very sorry state indeed. Often excluded from the group, they become what is referred to as 'super excreters'. That is, having tuberculosis in several organs, and capable of excreting huge amounts of infectious material from all of them, which is then available to any mammal unlucky enough to trip over it.

If they have been bitten by a tuberculous assailant, then generalised tuberculosis is often the result.

Behind the puncture wounds, this is the sort of infection they are harbouring. Pints and pints (or litres if you prefer) of pus - all capable of dripping from the original bite wound holes. And with the organisms travelling to other parts of the badgers' body, particularly his lungs and kidneys.

From the outside of the animal, the puncture wounds from inciser teeth appear quite small. Badgers are strictly territorial and will fight to protect their patch, so bite wounds are common. If the assailant has not got tuberculosis, these may heal.

But if it is infected.....

... then tuberculous abcesses form at the entry point. This is the cleaned abscess site of the badger pictured above.

It may be useful to point out that when a badger's kidneys are affected by TB (and this is a common site for lesions) he is capable of excreting up to 300,000 cfu (colony forming units) of bacteria in just 1ml of urine. Badgers are incontinent and will void this indiscriminately across grassland, at 30ml a squirt. It is also used as scent markers and as a 'fright / flight' defence if startled.
About 50 bacteria is enough to provoke a 'reaction' in a tested cow. And she is shot.

The reason for this posting, as we said at the beginning, a mirror image of one four years ago, is this blindingly naive and misleading statement by the Badger Trust, issued last week and criticising farmers for pointing out the effect tuberculosis has on badgers.
“We know of no scientific evidence or authoritative validation for a statement of that kind, though we are, of course, aware that similar but totally unsubstantiated claims have been made repeatedly by pro-cull lobbies in an attempt to emotionally influence the public to support their case,” the Trust said.

Well how about this for 'scientific evidence'.
An emaciated badger, drowning in the fluids issueing from a massive tuberculous pleurisy. This can occur when a lung abscess bursts and affects the surrounding membranes. Pleurisy is extremely painful, and this animal would certainly have shown respiratory distress before death.

That's what tuberculosis does. Abscesses (or lesions) burst or multiply to affect many of the organs of the body, until the animal starves or suffocates to death.

In 2003, on this very point, the 'welfare' of badgers with tuberculosis, we received the following answer from the then minister, Baby-Ben Bradshaw. [142462]
"It is difficult to make objective assessment of whether these animals suffer"
Those pics don't exactly show the individuals in glowing health and comfort - but let that pass...
Typically individuals may live for many months or even years while infected, showing no overt signs of clinical illness and maintaining normal body weights. Infected females often give birth and successfully rear litters.
Which is why they are so bloody successful as a maintenance host. TB kills alpacas who are equally riddled, and tested sentinel cattle, with little infectivety at all, are shot. But we do get the answer eventually, so bear with us:

However, post mortem findings (as our pics ?) where advanced pathological changes have occurred, particularly in the LUNGS ( my emphasis - ed ) indicate that during the final stages of the disease there would undoubtedly be an effect on the quality of life of such an animal. This stage is thought to last a few weeks at most".
Well that's all right then. They only 'suffer' for a few weeks (they think) This animal is drowning in its own body fluids (this is a close up of that 'massive tuberculous pleurisy).

Veterinary scientists advise that this badger would have been in extreme pain, possibly excluded by its peers, certainly starving and probably seeking shelter.

“Badgers have no divine rights over TB and as disease takes hold they lose bodyweight and condition, while the disease processes gradually invade and finally engulf their lungs over a period of many months.

“Proper appraisal will show, as with any species with a slowly developing pneumonia, that respiratory disease signs worsen as disease advances. Also kidney disease frequently occurs and as this can be acutely painful. In the badger this results in a more rapid deterioration of condition.

“Does TB cause painful disease? It is rather naive to assume that it does not.”

Some of these photographs were used to illustrate the following article: "The Cause of ill health and natural death in badgers in Gloucestershire". Gallagher J, Nelson J. and published in Vet Record. 1979 Dec 15;105(24):546-51.
An abstract from the piece, describes cause of death in these animals thus:
During the period 1973 to 1976 inclusive, 1206 badger carcases were examined for evidence of tuberculosis and other diseases. Tuberculosis was the major cause of natural death, killing 39 per cent of the natural death cases, followed by bite wounding and starvation.
But remember the words of the Badger Trust and the RSPCA - a badger does not 'suffer'.

Somebody needs a reality check.