Email received from Sabine Zentis of Castleview Longhorns and an expert in Bluetongue.
The declaration of vector free time is a very dangerous tool to ease movement restrictions if applied on a countrywide scale.
Even from one village to the next there are huge differences in climate, temperature and humidity so if you don't catch any midges in the village A - they might be active in village B.
Moving untested animals within the PZ will eventually result in a "spill over effect" as infected midges won't stay within the boundaries of the PZ.
Without sampling large numbers of cattle around the affected holdings and right into the SZ one can't get an estimate of how far the virus has spread already. Without this surveillance I would think blanket vaccination of all susceptible animals is the option.
The discussion about compulsory /voluntary vaccination is interesting. But DEFRA should be aware that, whatever option they choose, the requirements for surveillance, documentation, certification and follow up are the same and has to be performed by authorised vets. Otherwise there might be some trouble ahead for the export trade.
Surveillance is a big part of the BT control strategy and affected countries are requested by EU legislation to do a proper surveillance . That farmers are forced to pay for these surveillance (pre-movement testing) is an issue that should be questioned by the NFU, NBA etc. Countries can claim back expenditure for surveillance so farmers shouldn't pay the bill.
The situation in Germany is different. In the regions affected for a second time during 2007 seroprevalence in cattle is high enough to go for vaccination of youngstock only. But this is dependent on good surveillance and one has to take into account different farming systems. Cattle in open barns on straw and access to fields/pasture show a seroprevalence of 95-100%. But in cattle kept on slats/slurry systems and in regions with a lower than average livestock density only up to 50% of animals are seropositive. In these cases it is either test every animals and vaccinate accordingly or vaccinate the whole herd without testing. For the regions affected for the first time in 2007, saving the costs for blood tests, whole herd vaccination would be the preferred option.
All sheep (and maybe goats) should be vaccinated as seroprevalence is, compared to cattle, rather low.