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"Bovine" TB spreading to other mammalsBackground to the debate below
Farmers in the TB hot spots are in constant fear and often grief. In addition to cows, bTB is now affecting more and more alpacas, too. These animals develop open lesions very quickly just as badgers do. Inter-herd spread in alpacas is, unfortunately, likely to be fast and inevitable. This is not true of cows.With their permission, what follows are some of the current thoughts of Dr Colin Fink (in black) and the farmer, Pat Bird (in blue) on the subject of bovine TB and its spread to other mammals, including humans
There is a growing fear that TB is infecting other mammals and even human beings. Here is one email received at warmwell.com
"Have just heard that friends south of us on the coast, have lost 23 at the last swipe (dairy), they've lost over 200 now, in about 9 years. And others about 8 miles north, with their farm for sale, will lose 53 (out of 80 ish) dairy cattle. This is worse than FMD, Mary. It never ends. And won't until these infected badgers are removed from the equation. The level of tuberculosis contamination in the environment now, is phenomenal. Sooner or later it will splash out into more cats / pets / companion animals than we have now, and onwards into people. (The Cornish woman and her daughter both had clinical bTB and her dog is dead. The mother had lung lesions, the daughter was sputum positive. The dog extensive lesions in many places after selective euthanasia. All had the same 'spoligotype' of bTB that is circulating in tested slaughtered cattle, and the free ranging badgers 'known to inhabit her garden', one of which she 'rescued. She had not worked as veterinary nurse for three years before she became ill.) ...the. VLA are pretty sure that was direct from badgers, but waters were muddied by her previous employment as a veterinary nurse in 2004....(Read in full)In May 2009 , we reported that bTB had been found in several pigs in Cornwall over the past six months. The Farmers Guardian quotes one unfortunate outdoor pig farmer whose pig was confirmed with bTB after tests following the discovery of head lesions:
...vets tell me that by 1970, true cattle TB was all but eliminated. What we have now (they say) is badger adapted TB, feeding back up into sentinel tested cattle, and any other mammals who have the misfortune to come into contact with it. This level of environmental contamination is something we as human beings have not encountered before, and sooner or later it will blow up in Defra's face."
"These pigs had only been in woodland which is totally fenced in. They have never been near cattle yet they have picked up bTB. Wildlife infection is the only thing it can be. I think I was the fourth case in Cornwall in the past six months and my concern is that if they don't deal with this matter in wildlife, it is going to take hold in outdoor pigs..."According to DEFRA there were 10 confirmed cases in pigs across England in 2008 and it was also found in domestic cats, dogs, llamas, alpacas, deer, goats and sheep last year.
A veterinary nurse from Cornwall also contracted bTB. The FG included this ominous sentence from DEFRA: "We have legal powers to place any suspect animals under TB movement restrictions... The Government will become involved if there is a threat to cattle..."..but many are questioning just how effective Government involvement has been when the disease is ever more rampant in the UK and other species are falling victim to bTB.
A humane and knowledgeable article in www.farminguk.com in 2009:
"By foolishly allowing the TB bacillus to build up in the wildlife reservoir during the last 25 years, we are very nearly past the point of no return..... Just as eradicating TB was erroneously thought to be the only answer to the problem of tuberculous milk in 1932 (pasteurisation eventually solved that one), so attempting to vaccinate badgers now is too late and too costly in slaughtered cattle and disillusioned farmers.The writer, a Devon farmer of considerable experience, considers it is the only way ahead "with TB testing and the slaughtering of reactors a thing of the past. I hope I am around to see it."
Why did Defra take 11 years spending £23 million in vaccine research, before resorting to the BCG vaccine that is widely used in humans and is available in vast quantities from Sweden? And why, if that vaccine works for badgers, aren't we already starting a programme of cattle vaccination, and getting the rules about the use of vaccines changed in Brussels?" Read in full.
Getting rules changed in Brussels. They are not set in stone. As for foot and mouth, changing the rules on vaccination and thus enabling better vaccination research, is vitally important and urgent. Only then will modern technology be able at last to transform our archaic and inhumane animal health policy
From emails sent to warmwell.com Sept 21 2009 (On suspected human cases)
I read your bovinetb.blogspot reference with interest. M.Bovis is regarded as a zoonoses, of course there are well documented cases of it transferring to man. In the case of the cat diagnosed to have the disease, if the owners and immediate family remain asymptomatic, then all is well . Whether they have been exposed and have been infected with a small amount of the organisms and deal with this infection in the normal immunological way, is rather academic. Many of us meet M.Tuberculosis but remain entirely asymptomatic. The cat owners et al may be reassured. If they were to become ill and remain unwell for longer than a transient infection might be expected to last, then further investigation would be justified. As it happens we are able, and do, diagnose Mycobacteria of all sorts- there are many different types. ( we look for the Mycobacterial DNA and then sequence it to characterise the species of Mycobacteria). But no intrusive investigation ( biopsy of lymph nodes, lung biopsies etc) to find the organism, can be medically justified in someone who is entirely well. - It would be a hazardous undertaking.
22 September 2009 00:11
The real problem is that the organism hides, so unless there is an obvious focus for infection for example, a swollen knee or coughing rusty sputum or an eye with uveitis ( pain and loss of vision) you just do not know whether someone is infected.
You see the skin test is just as useless in us as it is in cattle. It will show that we have mounted a T cell response, so have met the organism ( I am not sure whether the skin test is Mycobacterial species specific: I suspect not) but so what? We have met some of the organisms and raised an immune response. That does not mean we are rampantly infected.
Tuesday, September 22, 2009 11:55 PM (From Pat Bird)
Agree with much of what Dr Fink says, except this:
"...the skin test is just as useless in us as it is in cattle. It will show that we have mounted a T cell response, so have met the organism ( I am not sure whether the skin test is Mycobacterial species specific: I suspect not) but so what? We have met some of the organisms and raised an immune response. That does not mean we are rampantly infected."
Yes and no. The intradermal skin test is the primary universal test for TB in cattle, and with that + slaughter most countries have cleared the disease altogether. The cattle skin test is 'comparative' in UK, as it compares a bovine TB antigen based on AN5 strain, to an avian TB antigen reaction, and records if the animal has mounted an immune response to either, and if so, the difference between the two. The only loopholes in its use are a latency 30/50 days prior to the skin test, or if the animal cannot mount an 'immune' response as it already has the disease. It is then said to be 'anergic'. I have endured years of consecutive 60 day skin tests - or our cattle have - and it does what it says on the tin.
Dr. Fink is quite correct to say, the test does not show that any candidate testing positve is 'rampantly infected'. In the case of cattle, they get no chance - they are shot. In human beings, the first line after contact with either a human case, or animal (farmed or domestic) should be a Mantoux test to detect if exposure has occurred. Which if it is positive, would certainly not mean invasive biopsies.
Records of recent cases describe bloods and PCR to see if sputum was ++ for bTB, together with Xrays. After which, a long course of appropriate antibiotics, if no evidence of operable lesions is detected . The Spanish couple with the alpacas are on a course of prophylactic antibiotics as the infection in their animals is so widespread.
It came as quite a shock to local AHO staff and vets that one of their colleagues contracted bTB via an alpaca postmortem conducted on farm. She developed bTB in the bone of her thumb, which required deep bone scrapes, reconstructive surgery and the inevitable antibiotics. A Cornish woman and her daughter both had clinical bTB and her dog is dead. The mother had lung lesions, the daughter was sputum positive. The dog extensive lesions in many places after selective euthanasia. All had the same 'spoligotype' of bTB that is circulating in tested slaughtered cattle, and the free ranging badgers 'known to inhabit her garden', one of which she 'rescued. She had not worked as veterinary nurse for three years before she became ill.
The amount of cattle we're killing due to 'exposure' to m.bovis in their environment, should be ringing warning bells that the amount of m.bovis is increasing. And it available to any mammal who cares to trip over it.
Any country which ignores a reservoir of bTB as we are doing (in wildlife) , is storing up problems for its human population in the future, and for just the reason Dr. Fink gave. It can wall-up and lurk deep within the body, until the immune system breaks down, when it will release, often decades after exposure. And that is precisely why it is a listed as grade 3 pathogen.
And HPA are not fulfilling their statutory duty if they fail to 'screen' contacts of anything positively confirmed. Particularly children whose immune systems are not fully developed.. (All in my opinion of course.)
September 23, 2009 10:17 AM - From Dr Fink
A very good discourse with much more detail than I gave. I would question one thing: a positive mantoux ( skin test with old tuberculin - a protein from the organism) can show previous exposure. Whether that is recent exposure to a suspected animal infection and thus infection or coincidental from a previous exposure is a bit harder to fathom.
Of course the cattle are not given the benefit of the doubt with a positive skin test. Only very modest numbers on post mortem are found to have lesions.
In my experience looking for any Mycobactarium in the blood ( by PCR ) even in broken down cattle - I had the opportunity with DEFRA a few years back, will not show organisms, so one may be falsely reassured. Sputum testing may show either miliary ( widespread infection ) or a more localised lung infection. But not always. Biology and organisms never do what they are told to in the text book.
The real problem as Pat says, is that there is far too much out there and we need to reduce the load in the animal reservoirs in a humane and satisfactory way. The trouble is we do not have a decent answer to that problem and any attempt will be messy, gird up the badger lovers ( understandably) and may not do the job very well.
I am still of the opinion that feeding stations with high dosage of triple antibiotics for say 6 months coordinated, could be worth a try. It would not be that expensive, but would need very good attention to detail. It would at least reduced the bacterial load in those wild animals that are a reservoir for infection and often excluded from the badger setts.