Saturday, May 21, 2005

To Test or not to Test?

Last year in answer to the exponential rise in Tb cattle slaughterings, our Ben - bless him he's back with the poisoned chalice again after the election - set up a couple of committees. One was the Pre-Movement testing committee, which had a remit from Defra to discuss - just that, 'Pre Movement Testing'.. Not whether pre movement testing worked or was effective as a disease control method - just do it. Sounds good though doesn't it? And cost didn't enter because the farmer was going to pay. Generously, our Ben agreed to pay for the tuberculin. That's 25p against the farmer's share of about £25 for the vet - twice.

We've told you several times on this blog, about severe cattle measures applied both in Ireland and the UK which have made not a dent in cattle Tb, if the reservoir in wildlife was not tackled simultaneously. And we (as ever) are most grateful to Captain Ben for the answers to Parliamentary Questions (archived) which confirm that "in the absence of a wildlife reservoir, regular testing (of cattle) and slaughter (of reactors) is all that is necessary".

But reporting to Defra this week the Pre Movement Testing Group, having cogitated, pondered and meditated their extraordinarily restrictive remit, expect Defra to implement some type of pre movement test next year.

Speaking at the launch of Defra's Animal Health 2004 report (not doing too well at that are they - cattle slaughterings up 30%? Not very well at all.) Chief Veterinary Officer Debbie Reynolds said "Tb is a regional problem and we need to keep clean areas clean. This depends on rigourous implementation of cattle controls and pre-movement testing would play a fundamental part in this".

That's easy then. Rigourous cattle controls and all the tb just - goes away? Errr no. It does not, as Ireland found in the 'Downie' era and certain DVM's found to their cost in the UK. (see posts and comments below)

But pre movement testing can be downright dangerous as farmers purchasing cattle so tested will assume, quite wrongly that they are 'clear' of tb. The skin test is not at fault, its implementation in this situation, combined with the expected industry 'exclusions' is.

We will explain;

1. The skin test has a latency of 30 - 50 days from exposure to m.bovis to the provoking of a skin reaction from that exposure.

2. The industry is likely to want at least an 8 week window from a pre movement test to selling, in which to arrange sales.

3. The industry is likely to ask for exemption for calves under 8 weeks, and slaughter stock which is probably OK, but also for store animals up to 15, 18 or even 20 months - which is risky.

4. The skin test is an 'excellent herd test' - John Bourne says so, so it must be. But on a single animal tested just once it's accuracy falls to under 70%.

So what have we got so far? 1 + 2 + 3 + 4 = a whole lot of 'missed' potential reactors.

The latency and 8 week exemption window add up to 4 months. That's 30 percent of reactors missed on an annual testing regime. Store animals exempt up to some 'teenage' cut off point, even though SVS tell us that 50 percent of reactors are in such young stock, would leave only a third of the animals tested reasonably covered by any pre movement test - and that compromised by the 'single animal' factor. Under conditions described above, we reckon about 60 percent of potential reactors would be missed.

But from Defra's Page Street disease control centre - it sounds good, and of course Defra isn't planning to pay.


Anonymous said...

Obviously, pre movement testing is going to miss a lot of reactors and is going to be very complicated (and expensive) to run. Lots more vets will needed to do all this testing. Where are they going to come from? The practice vets are very busy with routine testing (which you are not allowed to put off) and a great deal of extra testing because of the huge number of reactors, especially in the badly affected areas.

Matthew said...

Absolutely spot on. But Defra and the pre movement testing group are more interested in the public concept of 'being seen to do something about bTb' than actual disease control.

With the increase in herds under restriction needing constant 60 day tests - and no time off for good behaviour - routine tests are already under pressure.

One of this site's contributers has been under 'late test herd restriction' for 5 weeks. His own vet cannot give him a date being bogged down with 60 day retests. Defra can't help - particularly as they are laying off short contract TVI's while advertising in the current Vet. Record for - short contract TVIs! Strange way of keeping up staff moral. They did offer one solution to Matthew 3 though - change your vet.

Anonymous said...

Lay-testers is the simple answer. The RCVS are resisting such a move, but they can't hold out for much longer. The case for lay TB testing is almost as overwhelming as the case for industry funded pre-movement testing.

Matthew said...

...and if the bTb problem was tackled in a meaningful way - i.e in the round, there'd be no need for either lay testers or pre movement testing - or for this blog.

Anonymous said...

"in the round" presumably means cattle and badgers. You won't be able to tackle cattle without extra testing, therefore there will be a need for lay-testing.

Should Government decide to tackle the problem "in the round" farmers will kop it in their pockets; they will have to pay for the pre-movement (and possibly post-movement) tests PLUS they would have to pay for the badgers to be culled on their land by qualified professionals. Is the industry prepared to incur these additional costs ? I very much doubt it, because despite Government and every reputable vet advising that farmers should pre and post movement test their cattle, only a tiny minority of farmers take up the advice.

Matthew said...

The post above, pointed out the dangerous futility of pre movement testing as a means of 'disease control' - whoever pays.

The editors of this site favour a post movement test of breeding cattle of any age, moving to 2/3 or 4 year testing areas. But the problem is that unless they are isolated in dedicated facilities, a 'positive' test would bring the whole herd under restriction, and on this point we would agree with Elaine King, (that must be a first!) that grant aid towards such facilities would be helpful - and more importantly, cost effective.

On the cost of tests (or badger control), that is for the industry to fight over, but personally we favour the farmer paying up to a cut off point of say up to 10 percent of the herd replaced per year. If over that number of cattle are brought in, then the herd reclassified as 're-formed' and for lots of bio security reasons, moved to annual testing anyway, which is at Defra's expense - or the taxpayer.

Tuberculosis is a notifiable zoonosis, and under international public health rules, cattle must be tested. Costs of routine tests usually fall on the Department of Animal Health of the country concerned, with the farmer paying for any single animal tests. No other country that we are aware of, allows an acknowledged but unchecked reservoir of tuberculosis to flourish in its wildlife, with no efforts to control it.

So what the taxpayer is not getting at the moment is 'value for money'. Cage trapping as a means of control is weak, indiscriminate and open to abuse - or not done at all, and herds who have have had no contact with other cattle are going under restriction - and more importantly, staying there.

John Bourne, has said several times that if farmers were given appropriate licenses at the time bTb was confirmed as being NOT related to a cattle movement, then under supervision of Defra's wildlife teams, action would be swifter, more discreet and more thorough. Professor Godfray critisised trapping methods too.

On pre / post movement testing, we can only speak personally, but 3 of this site's editors have not bought in cattle at all for several years now, and it has not prevented the entrenchment of bTb.
When we could sell, then cattle left with full knowledge of date of last clear test, and further action was up to the buyer.

We agree that a post movement test, or 'date of next due test' would have many benefits and few drawbacks.

As to whether farmers are prepared to foot the bill for any of this, further back on the site we have reminded readers of the long term costs of letting this disease entrench in the UK's cattle herds.
From 2006, a new EU reg. means that milk from 'reactors' (as yet undefined) cannot go into the food chain, even if heat treated. Whether that is a single 'reactor cow', an 'inconclusive reactor', or a 'herd' which is under restriction and may throw up more reactors is not yet clear. The EU have also given themselves an opportunity, through the new veterinary certificate (see posts From Russia With Love etc- archived) to isolate 'regions with an endemic bTb problems' to protect trade with Russia.

This uncertainty of selling produce, combined with a downward push on cattle valuations and a lack of available insurance for any pedigree top up, may force farmers (if they want to stay in business) to sort out their own problems - at no cost to anyone at all.

Matthew said...

We don't have a problem with lay testers either - just the need for them under these circumstances.
Our contributer from NZ, is actually a lay tester himself, doing as part of a team, up to 3000 cattle/day.