Dr. Damien Barrett:

I thank the Senator. He asked about the level of TB in deer. We have conclusive evidence that deer are involved in the epidemiology of TB in County Wicklow. In one particular study, we found that up to 16% of deer that were tested post mortem were positive for TB. In the same study, we saw that between 30% and 35% of badgers from the same area were found to be positive for TB. Samples are collected from heads and plucks from hunted deer that have been presented to the regional veterinary laboratories for examination. The TB level to date has been of the order of approximately 2%. I accept, however, that the absence of evidence does not necessarily mean evidence of absence and we are encouraging farmers and hunters if they have any suspicions to present the heads and plucks from hunted deer.

The particular issue in County Wicklow, as Mr. Cashman alluded to, is the density of the population. That is an issue across the board when it comes to all species of TB. It is about the density of the population. There is a particularly high density - more than 40 per sq. km, as Mr. Cashman said - in County Wicklow. It is an issue of population density, and that goes for all species.

The Senator also asked whether the vaccination of badgers is effective. We have carried a non-inferiority trial, which has demonstrated that the vaccination is no worse than culling in the control of TB in the population. It has a similar effect in terms of the risk to cattle. That was a controlled trial in a controlled set of circumstances. When the vaccine is applied, it works. The difficulty is with the logistics of getting it out into a large population. The other thing to bear in mind is that if you are vaccinating, you are not culling. It comes back to the point that we may have a certain level of increase in the population. There are issues in respect of the logistics to get good coverage. Studies have shown that we need to vaccinate approximately half the badger population to get the level of protection we require in the population.

The Senator also asked about a vaccine for bovines. The difficulty with the current vaccine is that if we give the vaccine to cattle as it stands, they would fail a tuberculin test, which would have enormous implications for exports. That is currently the case. Our colleagues in the UK are developing what is known as a diva vaccine or a marker vaccine, through which it would be possible to differentiate an immune reaction that came about as a result of vaccination from an infection. They have completed the safety trial. They have demonstrated that this vaccine does no harm. They are a bit away from getting the vaccine to the market and getting market authorisations and anything like that.

The other difficulty will arise in respect of the World Organisation for Animal Health and the whole issue of certification and getting acceptance for a product to be certified as TB-free if it has been vaccinated. There could be a lot of politics involved in that.

The Senator also asked about genetics. There is no doubt but that genetics on their own are not a silver bullet, but they are a part of our arsenal to deal with this. Animals with a high susceptibility to TB on the basis of the genetic tests have been shown to be almost one and a half times as susceptible as their comrades with a high resistance. If there is enough of an infectious dose, they will succumb. However, animals with a higher resistance have a greater ability to resist becoming infected.