Badger cull now planned for England

[Eryri]

Originally Posted by GavinWheeler

Absolutely false. Given that the RBCT showed that culling increases the level of TB in badgers, a cull would reduce the effectiveness of vaccination, fir the reason you give.

This point has been made to you very clearly several times before this.

The RBCT were conducted in areas where no strict cattle movement controls were in place and most of the areas did not have natural boundaries to perturbation. The areas where there were natural boundaries, even without strict cattle control, there was a marked reduction in bTB outbreak, and this reduction in infection was maintained after the cull period ended. As for your claim that a cull would reduce the effectiveness of a vaccination programme, that is quite bizarre. There is no plan to vaccinate dead badgers, and any perturbation effect is mitigated if the remaining live ones are vaccinated.

[Eryri]

Originally Posted by GavinWheeler

Riight - again you clearly don't understand the terms you are using. A 'negative transmission rate' would imply infected badgers becoming miraculously healed by contact with healthy ones.

A negative transmission rate is a very clearly defined clinical term used to describe how a reduction in population density reduces the transmissibility of a disease. It means that lower population density reduces the occasions infected animals comes into contact with un-infected ones. An epidemic is where the transmission rate is positive. When a negative transmission rate occurs, the infection eventually dies out, or becomes clinically dormant. I'm quite surprised Dr Gavin Wheeler, that you are not aware of this.

[Eryri]

Originally Posted by GavinWheeler

Badgers shed the bacillus, true. But the post mortem evidence shows that most cattle are infected via their lungs, not stomachs.

Please send me photos of your cows that stop breathing while chewing the cud.

[GavinWheeler]

Originally Posted by Eryri

The RBCT were conducted in areas where no strict cattle movement controls were in place and most of the areas did not have natural boundaries to perturbation. The areas where there were natural boundaries, even without strict cattle control, there was a marked reduction in bTB outbreak, and this reduction in infection was maintained after the cull period ended.

Wrong.

There were cattle movement controls at that point in time - just not as strict as now. Even now, we have not implemented all the cattle control measures recommended by the RBCT.

The RBCT zones which had hard boundaries had similar result on TB in cattle as those without - it was only the negative effect on badger TB that was mitigated by such boundaries.

In all areas the reduction in infection is expected to be transient - indeed none was measurable only a few years after the cull ceased, only to re-establish itself for reasons not yet understood.

Originally Posted by Eryri

As for your claim that a cull would reduce the effectiveness of a vaccination programme, that is quite bizarre. There is no plan to vaccinate dead badgers, and any perturbation effect is mitigated if the remaining live ones are vaccinated.

Well you did indeed seem to suggest re-vaccinating badgers after vaccinating them once and then incinerating them. But that's just your wacky dysfunction.

However, my claim is very simple - and backed up by the science.

1. Culling increases the level of TB in badgers
2. Vaccination of infected badgers has no effect
3. Therefore Culling reduces the effectiveness of culling.

Simple enough for you?

[GavinWheeler]

Originally Posted by Eryri

A negative transmission rate is a very clearly defined clinical term used to describe how a reduction in population density reduces the transmissibility of a disease..

Evidence for this?

Given your proven past of wild and false assertions, and using technical terms without knowing what they mean, I'll stick to my initial assumption that 'transmission rate' means what it says and your statement is gibberish.

Originally Posted by Eryri

Please send me photos of your cows that stop breathing while chewing the cud.

Muppet. Again!

They don't stop breathing while chewing the cud - and our animals have never had TB anyway.

Rather post mortems show that the majority of infections in cattle occurred through the respiratory route - i.e. lungs, not stomach.

[pressld2]

Let's keep it civil gents!

"Negative Transmission Rate" is meaningful in packet switching networks and I can also find it being used in the field of energy transmision, but not in epidemiology. With infections, transmission rates can go up or down but they can never fall below zero as that would require contact between a healthy and infected animal to result in the infected one being cured. Therefore we can talk about "reduced transmission rates" but not negative ones.

Gavin, I think Eryri is saying that because cows continue to breath while eating then an infection picked up in their food can make its way to the lungs. This seems reasonable to me. As it is considerably easier for bacteria to enter the blood stream through the lungs than it is through the stomach then it is still possible that cattle infected through the respiratory system picked up the infection with their food.

None of which alters the simple fact that culling badgers spreads TB wider than leaving them be does.

Dave P.

[Eryri]

Culling involves trapping and shooting. Vaccination involves trapping, vaccination and release.

When 50% of a badger population has been vaccinated, you have a 50/50 chance that a trap will capture a badger that has already been vaccinated. If a badger already had bTB in the first place no amount of vaccinating will cure it, and vaccination a second time will have no additional effect (assuming boosters are not required and multiple injection of the mild infection is not harmful). It is therefore impossible to ensure all badgers are vaccinated.

The deployment process accepts that a proportion of badgers are never vaccinated, some of which will also be infected. The theory/hope is that the number of badgers infected (but not cured) co-habiting with the number of badgers that are never vaccinated, do not continue to spread bTB within the badger population and also to cattle.

It should also be noted that a cow cannot spread the infection to a badger that is dead. It can, however, spread an infection to any badger that has not been vaccinated, or born since the last vaccination. The chances of cattle/badger cross infection is directly proportionate to the number of badgers on the farm.

-----------------------

What cattle control measures recommended by the RBCT have not been implemented ?

[Eryri]

In transmissability, a rate of 1 is considered neutral.

A positive transmission rate is :
2 => 4 => 8 => 16 etc.
Rate = 2

A negative transmission rate is :
16 => 8 => 4 => 2
Rate = 0.5

In bacterial diseases where transmission is by contract or close environment, the density of the susceptible host population directly effects the transmission rate.

Culling introduces a negative transmission rate by removing susceptible animals.
Vaccinating reduces the proportion of susceptible animals in the population.

Both result in a negative transmission rate, where the number infected (after predation) fall below 1 to 1.

[pressld2]

Originally Posted by Eryri

It is therefore impossible to ensure all badgers are vaccinated.

It is not necessary to vaccinate 100% to eradicate a disease. Small pox has been completely removed from all human populations but not one single country ever achieved 100% vaccination.

It's also possible that immunity may be passed on to new born cubs via their mother's milk, particularly if the vaccination is a live one. (Does anyone know if it is?) This is one of the reasons that human mothers are encouraged to breast-feed.

We will have to await the results of the trials to know just how effective or otherwise vaccination may be. With culling we don't have to wait. We've already got the results and they tell us very clearly, however much people try to spin them, that culling makes matters worse not better.

Dave P.

[pressld2]

Originally Posted by Eryri

A positive transmission rate is :

2 => 4 => 8 => 16 etc.

A negative transmission rate is :

16 => 8 => 4 => 2

We're probably just arguing semantics here but what you have described above are an increasing and a reducing transmission rate. As neither ever falls below zero they are both positive. But if you want to call a reducing transmission rate a negative one that's fine by me - I understand what you mean by it.

Dave P.