August 4, 2007

experts respond to Foot and Mouth Outbreak

Carl Padgett, British Cattle Veterinary Association President Elect, said:

“The discovery of cattle infected with FMD in Surry is extremely worrying. A detailed contingency plan for the handling of FMD outbreaks exists, and it would appear that the measures outlined within it are being employed by Defra. Efforts must first be focussed on 2 fronts, the prevention of further spread of infection, and the identification of the source of infection.

“It is not currently known how disseminated this infection is. A GB wide ban on the movement of susceptible animals (all cloven hooved animals, particularly cattle, sheep and pigs) is therefore essential to reduce the potential for further spread around the country. This action was delayed in 2001, and at that time there were already 100s of undisclosed infected premises as a result of sheep movement when the initial case was being investigated allowing further movement to magnify an already dire situation at that time.

“Further spread is also reduced by the removal of infected animals and their contacts that may be incubating infection. The whole herd slaughter of cattle on this farm is also essential therefore and is underway. Transportation of carcases in sealed containers with appropriate disinfection procedures to dedicated incineration plants is of low risk to further disease spread. The 3km protection zone in place will result in the inspection of local livestock and an assessment of the level of contact any other livestock have had with the infected premises. A risk based veterinary epidemiological assessment of the level of contact will help decide whether in-contact livestock should also be slaughtered or be monitored for signs of infection. This is also underway.

“The most likely routes for further dissemination of infection are the movement of infected animals and their contacts, the movement of farmers and other stockmen who have been in intimate contact with infected animals, and the potential airborne route from the dispersal of a plume of virus created by excretion from infected animals. The latter route is much more common in the case of pigs, that have the ability to massively magnify the absolute quantity of virus in the environment. Infected cattle and sheep generally produce less virus, and so the plume effect is less of an issue. Meteorlogical data coupled with local surveillance data will help predict the likelihood of this, as happened with the Isle of Wight outbreak some years ago.

“The risk that members of the public will disperse infection is very low. Restricted access to known infected premises and their contact premises is wise, as infection may be transferred in faeces carried on boots etc, even though the risk of this is low. Where there is no known infection present, public access to the countryside poses little or no risk to further spread of disease.

“Vaccination for FMD is possible, but is a highly complex issue. Suppressive vaccination can be used in isolated incidents to reduce the further spread radially from infected premises. Vaccination should not be used as a knee jerk reaction. There are several strains of FMD ‘O’ type virus, the correct strain must be identified and the suitability and availability of vaccine stocks assessed before any vaccination is undertaken. The Contingency Plan states that a vaccine policy should be a protective ‘vaccinate to live’ policy, where it is intended that any vaccinated animals should live out their productive lives post vaccination. This is particularly important for the survival of rare breeds with an endangered gene pool, and certainly is of great potential there. It is very difficult to identify the difference between a vaccinated animal, an infected animal, or a vaccinated animal that has subsequently been infected and is acting as a carrier for disease. Marker vaccines and differential diagnostic tests that exist are not reliable enough to distinguish between these animals. It is therefore possible that the infection may be harboured by vaccinated animals, and for eradication to confidently be achieved vaccinated animals are often slaughtered. In 2001 with outbreaks in Europe where suppressive vaccination programmes were used around isolated infections the spread of disease was limited but the number of animals culled per infected premises was dramatically increased due to the slaughter of local vaccinates. A ‘vaccinate to live policy’ is therefore very difficult to achieve, particularly if national freedom is to be regained for international trade purposes. Rare breed herds so vaccinated would have to be managed in a biosecure fashion that would prevent the spread of potentially undisclosed virus.

“Effective forward tracing of the movement of potentially infected animals and their contacts to other premises will also help to chase the disease in order to remove any other infected animals before they too are able to spread disease. Movement records through the British Cattle Movement Service can be analysed, as can other records for movement of pigs and sheep.

“The efforts concentrated on recorded animal movements and other contacts will also help to backwardly trace aiming to identify potential routes of introduction of the virus to this infected premises, which is obviously key to informing future decisions and controlling the outbreak.”

David Catlow, British Veterinary Association President and Dr Freda Scott-Park, British Veterinary Association Past President, said:

“The BVA is appalled by the news that FMD has returned to Great Britain. Because of the highly contagious nature of this disease it is essential that the source of this outbreak be identified as soon as possible. The immediate countrywide movement ban on FMD-susceptible animals as part of the new Defra Contingency Plan is a key measure in the control of the spread. The veterinary profession will be standing by to offer advice on clinical signs and biosecurity measures to concerned animal owners, be they farmers, smallholders or owners of just one or two pet farm animals.”

Nick Blayney, British Veterinary Association President elect, said:

“The important thing is to speedily identify and put down any infected animals before they suffer and before they spread infection any further. Government vets will be tracing animal movements in and around the area, and any other possible sources of infection.

“DEFRA has got a contingency plan, based on the lessons learned in 2001, which it is already rolling out. Until we know what is going on, it is absolutely correct to stop any animal movements around the country. Farmers will be alert for signs of disease in their animals, and informing their local animal health office if they have any suspicions. The picture will become clearer over the next 48 hours, as we gather more information. The speedy response in diagnosis and control will surely have helped to contain this serious disease.”

A spokesperson for the National Farmer’s Union, said:

“The NFU is in detailed discussions with DEFRA following confirmation of a case of FMD in cattle on premises in Surrey.

“The NFU fully support the blanket suspension of all livestock movements, market and shows in GB. We believe that this is the right response to this incident and it is vital that we do everything possible to stop the spread of this disease as quickly as possible.

”We would encourage all livestock keepers to be vigilant and monitor their livestock closely, full details of the symptoms of FMD are available on the DEFRA website and anyone who has any concerns at all should discuss them with their veterinary surgeon.”