August 8, 2007

experts respond to Foot and Mouth outbreak

Carl Padgett, British Cattle Veterinary Association Junior Vice-President , said:

“The ban on movement of animals to prevent the potential spread of FMD is supported. Until the epidemiological evidence is strong enough to conclude that the infection has not been translocated to other parts of the UK this movement ban must remain in place. Enough time must pass to allow for sufficient incubation of the virus to cause clinical signs in livestock. The tracing of animal movements from the IPs and out of the PZ is of great importance. Increased vigilance and reporting of potential disease by farmers is essential to assess the extent of spread, and the more time that passes with no confirmation of disease in the rest of the country raises confidence that spread has been limited. This heightened state of vigilance must be continued to boost this confidence and support decision making. It is too early yet to talk of exit strategies for this policy.

“Movement between farms is a long way off, but low-risk licensed restricted movements must be considered. Milking cows within a premises, and movement for emergency veterinary attention within a premises are currently allowed outwith the surveillance zone. There are 3 types of animal movement which need to be addressed:

“1 – Movement to slaughter: This is already allowed in Scotland. The meat industry needs to regain its supply of fresh meat, and if it does not occur from British farms, retailers will increase their imports from abroad, threatening loss of UL market. Animals ready for slaughter are also backing up on farms and will pass their optimal slaughter condition if they do not move soon. If they pass this optimal condition, the carcasses will be less desirable and incur economic loss.

“Movements direct to the abattoir from the farm of origin from farms outside the surveillance zone should be of low risk. The animals are not mixed with others from the farm of origin until they reach the lairage at the abattoir and all animals are then slaughtered preventing any onward spread. Appropriate cleansing and disinfection (C&D) of vehicles prior to loading at the farm and after unloading at the abattoir reduce the risk of vehicular spread. It would be preferable for the abattoir to have C&D facilities on site to minimise risk of spread by vehicles after unloading.

“2 – Welfare movement. There are a growing number of animals being kept in the wrong place at the wrong time that would otherwise have been moved to other premises had it not been for the movement ban. Pressures on housing and feed supplies, particularly grazed grass, potentially threaten the welfare of animals. Where welfare is compromised as judged by the opinion of the farm’s veterinary surgeon, a case can be made for a low-risk movements to more suitable facilities under appropriate supervision and with appropriate C&D.

“For welfare movements particularly, some local discretion of the local Divisional Veterinary Manager should be considered, who can assess the local situation with local knowledge and make appropriate decisions taking account of the national situation.

“3 – Fallen stock. The removal of fallen stock from farms has halted. The Fallen Stock Scheme is unable to operate and carcasses are building up on farms as time goes on. Decomposing carcases pose a risk to animal health, human health and to environmental contamination. Scotland has temporarily lifted it’s ban on on-farm burial to ease the situation.

“On-farm burial in itself is not risk free, and should only be undertaken within strict guidelines, which the Scottish Executive have detailed in their licence. The protection of watercourses is paramount.

“Moving carcases direct from farm to disposal plant, with no farm to farm collection, could be considered as confidence grows in the epidemiological evidence. Appropriate C&D and suitable availability of onward facilities for dealing with offal etc all need to be arranged in parallel.

“Practical issues must all be considered. In the lowest risk areas it would be hoped that a general licence could be allowed for slaughter and fallen stock, where animals can be moved after farmer inspection. This would be similar to the position in Scotland. In this way, a regional approach to lifting restrictions may be possible.

“For welfare movements and higher risk movements to slaughter and fallen stock, individual licenses for individual farmers to move could be considered. For welfare and slaughter, this should involve inspection by the farm’s vet prior to issuing the license to ensure freedom of clinical signs of FMD. Higher risk movements would be those associated with a tracing movement from the high risk area, or may even be in a buffer zone created around the SZ to account for the potential of further outward spread.

“Similar considerations were made in 2001 and so the mechanisms for releasing restrictions are better understood now compared with then. Experiences from that time should be drawn upon to solve these problems. Individual licences were appropriate at that time due to the widespread nature of the disease. Should this outbreak prove to be more localised and successfully contained, a regional approach via general licences may be more appropriate.”

Keith Plumb, Chairman of the Pharma Subject Group, Institution of Chemical Engineers, said:

“There are two routes by which the Foot and Mouth Virus could have been accidentally carried out of a biosecure facility. The first route arises from a failure in the gowning procedure and the second from a failure in the solid waste handling system.

“In a biosecure facility used for research on or manufacture of animal vaccines it is necessary for the operator handling the virus to be fully gowned up. This would require an all over suit, face mask, gloves and overshoes. This gown serves two purposes, first it prevents the operator from being contaminated with the virus and it protects the vaccine from being contaminated by any micro-organisms on the person. Problems can occur in a number of ways, the clothing has to be put on correctly and more importantly removed correctly. If clothing is removed incorrectly the any viruses on the outside can be transmitted to skin. There are further possibilities for mistakes in the showering and decontamination required after degowning, it would be easy for someone to skimp and not spend the required time. Finally the used clothing has to be treated correctly, reusable clothing must be decontaminated using steam and disposable clothing becomes solid waste.

“Solid waste comes in a number of forms and can be difficult to decontaminate due to its awkward shape. Automated steam decontaminate would be the most effective but not everything is suitable for this and chemical decontamination has to be used. This can be a manual operation and very operator dependant, again it is possible to skimp on the treatment and not properly decontaminate the waste. Once the waste has been through the decontamination process anyone handling it would expect it to be safe and would probably not take any precautions, so any waste that had not been properly decontaminated could easily contaminate anyone handling it.”