Bluetongue

We are still learning more things about Bluetongue and it surprises me that for a disease that was first recognised in the eighteenth century there are still large gaps in our understanding of the way it affects livestock. Certainly Bluetongue has never been this far north before, we cannot rely on it spreading only slowly here because of our colder climate. It would be wrong to speculate that symptoms will be mild if the virus is transmitted poorly by the midges that we have. What is apparent is the way that cattle act as a reservoir of infection for the virus. It would seem that it multiplies readily in cattle and that the midges will then pass it on to sheep and cause serious disease.

How it affects you

Also it is not apparent how BVD fits into the picture. It is known that BVD suppresses the immune system of cattle and makes other infections, for example bovine tuberculosis, far worse than they would normally be. It is thought that some breeds of sheep are particularly susceptible to the infection, Texels are thought to be more at risk than most. Reports from flocks that were affected by the disease on the continent last year, some of them with only minimal symptoms indicate that they have had a poor lamb crop this year. It is hoped that vaccination will help to reduce these losses.

Over Wintering

It is not at all clear just how reliable the serology test is for the virus, there seem to be a number of false positive results that have not been confirmed when more specific tests for the virus have been undertaken on the same animals. It has been noted that pregnant cattle from the protection zone that have tested negative on the serology test have produced calves that are virus positive. Is this the way the virus starts up again so successfully after the winter?

Are we ready?

I do not think we are ready to tackle Bluetongue yet. There has been six months at least to prepare for it’s re emergence in the spring, but there are few signs that it will be possible to reduce the outward spread of the infection. There does not seem to be any active surveillance going on to find out where it has got to. Figures for the end of last week reveal one hundred and twenty two infected farms, there will be more where infection has not been noticed. There have been several scares in Shropshire already, one on a farm of one of our clients that has eventually tested clear. It is not far away. It must be of concern that animals are still being imported from the infected areas of the Netherlands, Germany and France. I understand the Ireland is proposing to ban the import of any cattle and sheep that have ever been in any of the protection zones since August 2006. Surely we should do that as well.

Our National Strategy

It is difficult to understand why DEFRA has not taken advantage of European funding and introduced a compulsory vaccination policy. That way we could target limited resources to specific areas and stop the virus spreading further west and north. It would be better if cattle were vaccinated first as they require two doses of the vaccine four weeks apart, this has to be done to check the numbers of midges that can become infected. It is still important to vaccinate as many sheep as possible as stocks of the vaccine become available.

At the moment the vaccine does not have a product license and it has not been tested to determine how effective it is so a great deal will be learnt during the course of the summer. It would be better if the vaccine could be licensed for goats and farmed deer as well as cattle and sheep as they are also reservoir hosts of the infection. It is very un fortunate that there will be only limited supplies and that it will arrive late when the infection is active again. I will be most disappointed if Forte Dodge is not allowed to supply the vaccine as well now that they have 5 million doses that could come into the country next month.

Can we stop it?

Bluetongue is a complexed disease by the way it is transmitted between animals and the way it survives over the winter. I have no confidence that you can do anything to effectively stop midge bites by the use of insecticides or housing animals at night. It is very difficult to keep the insects out of most buildings. It is not practical to move slurry stores or muck heaps to keep the vector away from your stock. There are electrically powered machines that attract midges and kill them, but they are very expensive and were designed to keep the insects away from suburban gardens rather than off a farm. This is not a disease that you can avoid by strict bio security measures, disinfectant will not help to control it. If you should be unfortunate enough to be affected you can expect severe disease and poor fertility afterwards especially in sheep.

Vaccination

 Bluetongue is a notifiable disease, there is no compensation or slaughter policy and it is by no means clear how long you will be under movement restrictions if it were to occur. We do not know when the vaccine will be available for us to use. As things are at the moment vaccination is the best thing you can do to safeguard your stock. It would be better to vaccinate to prevent rather than wait and see. In order to give the vaccine the best chance to work it should was given on its own and not used at the same time as other inoculations.

Low Dose

The vaccine will not work if you wait until your neighbour has Bluetongue before you order it. It is expected that it will be a low dose dead vaccine. 1ml injection once for sheep and twice for cattle four weeks apart. The injections will need to be repeated each year, hopefully early in the spring. We have an order list at the Surgery and will supply farms as the vaccine becomes available. Farms at the top of the list will be supplied first if there are limited stocks available.

Vaccination Amnesty

The cat and dog vaccines need to be repeated each year to work properly, especially to protect dogs against leptospirosis. Until the end of April we are offering to give a full course of injections for the price of a single booster for any animals that have missed out on their annual boosters.

Cat Neutering.

Cats Protection are running a neutering campaign for farm cats. For a limited period if you pay £5 they will cover the rest of the cost of neutering each cat that you bring to the surgery. No forms no fuss we just need you to bring in the cats.

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