This document was produced by MAFF as a specific response to the FMD outbreak in the UK in 2001 and was made available on their website. Risk Assessments and specific recommendations related to the conditions in the field at the time and should be viewed in this context as they may not be applicable to outbreaks occuring under different circumstances.
Foot and mouth disease
26 April 2001

MAFF: Veterinary Risk Assessment No.13: What is the risk of causing new outbreaks of FMD by moving hay and straw onto a farm?

1. Major risk factors

i. Both hay and straw have been identified as vectors of the FMD virus. The Japanese outbreak in 2000 was attributed to infection in straw imported from China. The Importation of Hay and Straw Order 1979 is designed to prevent the accidental importation of infection into Great Britain. A number of recrudences of infection in the 1967/8 epidemic were attributed to infection remaining on such material after infected farms had been cleaned and disinfected. Hay and straw must therefore be regarded as risk materials which are potentially capable of introducing infection to previously clean premises when fed to, or used as bedding for, livestock.

ii. Hay and straw for sale will be derived, in the main from arable farms and land which is not grazed by livestock. In any case, hay and straw in Great Britain at present has been produced before FMD entered livestock. They can only carry virus that has been deposited on them, directly by animal contact or indirectly by aerosol. In unopened stacks and bales the major risk is surface contamination, though rodent infestations can spread infection more widely, particularly on infected premises. Used litter and partly used bales carry greater potential risks.

iii. The greatest risk is material from infected but undiagnosed premises. Material on known, or suspected Infected Premises, will be destroyed or disinfected there: it can be moved from the premises under license.

iv. Traded hay and straw is likely to be in the form of bales that will have been stored under temporary or permanent cover. This minimises the risk of virus deposition from an infectious plume. It is also pertinent that there have been few pig outbreaks so far, and pigs are the only significant generators of virus plumes.

v. The FMD Order 1983, makes no provision to control movements of hay and straw which are not on infected premises (though it does for manure, slurry and litter). The Order takes account of all the recommendations of the Northumberland Committee, and it can be assumed that hay and straw were not identified as a significant risk in the 1967-68 outbreak, except in the context of recrudescence of infection when infected premises were restocked.

2. Risk management options

i. Historical evidence suggests that the risk from hay and straw is very low and of insignificant practical importance. This risk has to be balanced against other considerations such as animal welfare.

ii. With the exception of premises which are infected or suspected to be infected there is no statutory provision for preventing the movement of domestically produced hay and straw from or to farms in Great Britain. Farmers should exercise caution when purchasing. Risks can be minimised by:

• buying from reputable sources, preferably in an arable area
• spraying the outside of the purchased bales with a mist of FMD disinfectant

3. Recommended action

i. No statutory action additional to that which is already in place is needed.

ii. Owners of susceptible animals should exercise caution when purchasing hay and straw. Risks can be minimised by

• Buying from reputable sources, preferably in an arable area.
• Buying hay and straw which have been stored on premises in an infected area where there are no susceptible livestock, or on premises outside an infected area.
• Spraying the surface of purchased bales with a mist of FMD disinfectant.

Contributors:

Dr. A. Donaldson IAH Pirbright Labratory
K. C. Taylor Veterinary Consultant