Bluetongue Virus Type 3
The Bluetongue Hotline: 024 7771 0386
Currently there is one Albion, an in-calf heifer, locked down in the ‘Bluetongue Temporary Control Zone’ (TCZ) along with about 450 other holdings with sheep, cattle, goats or alpacas on.
Last night, a meeting was held in a village hall in the middle of the area affected in Kent and it was packed out. Representation from APHA, Trading Standards, NFU, FCN and even a top scientist working on the virus, from the University of Nottingham Vet School, were there – but not anyone from DEFRA. The audience was packed with farmers, small holders, vets and auctioneers and even the rural police.
Bluetongue is transmitted by biting midges but is not usually contagious by direct animal to animal contact. So far, there have been 11 cases on 6 holdings thought to have been caused by infected midges blown in from the Netherlands where the outbreak has been spreading. Each of the UK cases has been put down, to lessen the chances of further spread of the virus. But so far since the virus has not spread from animal to animal within the UK, the situation here is not yet classed as a ‘disease outbreak’. The positive cases have all been shown to contain the virus, by detection of viral genetic material in blood samples. Although this means that the animals have recently been infected, it does not conclusively show that they are still capable of transmitting the virus. It is likely that the infected carrier midges have died now that it has got colder; and it is currently too cold for new midges to become fully infected to the stage where they can pass the virus on. So why take such radical action?
Even in cold weather a few midges can remain on the infected farm, so animals are killed to lessen the chance of midge biting infected cows or sheep and spreading the disease. When infected midges lay eggs, the newly hatching midge larvae do not carry the bluetongue virus, which is good news. However, in cattle and sheep, the disease, once caught can spread vertically from cow to her calf or ewe to lamb and the virus can survive for long periods in the testes and is released into semen.
So, even though most adult midges, healthy or infected, will die over winter, we do know from previous outbreaks in the Netherlands that the virus can ‘overwinter’ successfully. If infected ewes or cows produce infected calves or lambs next spring, the birthing materials may also contain the virus. The new crop of emerging midges can bite newborn animals, or contaminated materials including bedding may be ingested, re-starting a bluetongue outbreak. (NB If an infected dam survives and fully recovers from bluetongue, the progeny she produces later on will not be infected with bluetongue at birth. Colostrum will also contain antibodies to the virus and will help to protect the newborn calf or lamb from infection.)
One farmer pointed out that we coped with the first bluetongue outbreak caused by bluetongue type 8 in 2007 without a TCZ. The reply was that last time there was a year between the virus initially spreading from the Netherlands to the UK and in that time, they managed to produce a vaccine and implement DEFRA’s ‘Joint Action Against Bluetongue’ (JAB) vaccination campaign. This time, bluetongue type 3 has been discovered in the UK only two months after being found in the Netherlands and no vaccine has as yet been produced.
It was emphasised that in the Netherlands, some farmers have lost 30% of their sheep, and although the disease is usually less severe in cattle, some deaths have also been reported. There are some very sick animals; they have fevers and blood vessels are damaged, hence the symptoms of red around the eyes, muzzles, hooves and teats. Leaking of serum from damaged blood vessels into the air spaces of the lungs, leading to frothing, can make breathing more difficult or even impossible. In very severe cases swelling around the head and neck can restrict blood flow, causing cyanosis of the tongue, hence the name ‘bluetongue’. There can be a significant drop in milk yield and many females abort in early pregnancies. Along with the animal-movement restrictions, this all brings huge financial losses and distress to farmers.
The cases in the Netherlands have spread from single figures to thousands in just two months. This explains the action from APHA to impose the TCZ. If the bluetongue virus can be controlled now, then we may either prevent or delay a national disease outbreak. If it can be delayed, it may give scientists enough time to develop a vaccine for this strain. Back in the later part of 2007 into 2008, many farmers vaccinated their animals against bluetongue type 8; achieving 60% take up and, like Covid vaccine for ourselves, enabled a barrier to form against the disease, preventing re-emergence of a large scale outbreak in the UK in the Summer of 2008. However, the virus continued to rampage through most of Northern Europe and down through France in 2009 and 2010, with massive losses.
Meanwhile, testing of all cattle, sheep, goats and alpacas is carrying on within and around the TCZs. Farmers want to know how long the TCZ will remain for. Some are about to lamb, some need to sell stores or fatstock, some are on temporary grazing keep and the food has run out. Real financial problems are occurring that are out of the farmers’ control. Will the government help? APHA confirmed that only infected animals which are destroyed will be compensated for, nothing for the loss of income or extra labour testing animals.
Special movement licences can be applied for from APHA, however animals in the TCZ are not allowed out of the TCZ, if they are out at keep, they cannot come back. It was estimated that it would take until the end of February to test all animals in the TCZ meaning that it is likely, depending on the results, that the TCZ will remain in place until then.
If any new cases are found outside the TCZ, then the control zone will either be enlarged or, if further away, a new 10 km diameter circle will form a new TCZ.
The bite of a fully infected midge very efficiently transmits the virus even in a single bite. If midges become infected in the UK by biting infected animals, then pass it on by biting naïve animals either now or in the next few months, then a disease outbreak of bluetongue will be declared. Then infected animals would no longer be slaughtered as the virus in the midge population is not controllable and the TCZs would likely be lifted, or perhaps extended to include the whole country because there would be no hope of containing the virus. Let’s hope, if that happens, it will be many months from now and a vaccine will have been developed and manufactured.
Are there any precautions everyone can take? We need to be vigilant, looking for symptoms. Bluetongue is a notifiable disease. Never re-use a needle between animals when injecting. Think where manure is stored, as these produce midge breeding habitats, and should be kept away from livestock housing. Test any breeding stock being brought in.
There are a couple of zoos within the TCZ and antelope, camels, giraffes and even elephants can become infected with bluetongue virus. APHA admitted they had delayed testing these very rare breeds, leading to it being pointed out that there are some extremely rare farm breeds including the Albion within the TCZ. There was no reply to this, so let’s hope that this disease is being quickly controlled and, just like the zoos, rare breeds catching bluetongue will not be a problem that we have to deal with.
It was asked if APHA would be working and testing over Christmas and not going to ‘shut up shop’ for a fortnight. APHA assured everyone that they would be working every day. However, who wants to blood test a load of cattle with no good handling facilities on Christmas Day or Boxing Day?
Happy Christmas!
5/1/24 Update: There are now 36 infected animals on 20 different premises but no evidence that it is circulating in midges.
With testing at the farmer's cost at both ends, it is now possible to move anim,als out of the TCZ
There are now designated abattoirs outside the TCZs that can be used for animals within the TCZs
