FMD:

FMD: EXMOOR, DISINFECTION & RED DEER

Report by Kevin Taylor, Veterinary Consultant for MAFF
23^rd April 2001

The National Park Authority are concerned to prevent the spread of FMD to the 3,500 – 4,000 red deer on Exmoor.Their concern is reasonable, reliance on disinfection is not.The Northumberland committee, in part 2 of their report on the 1967/68 epidemic, reported that the scientific advice is that “the disinfection pads on public roads would do nothing to prevent the spread of FMD virus”. To be effective, cleansing and disinfection need to be done properly, a time consuming and difficult business.
There is no doubt that livestock vehicles can transmit infection, usually to animals carried subsequent to a load of infected animals when cleansing and disinfecting (which is a statutory requirement) has not been done or has been done ineffectively. The risk from other vehicles, particularly if they have not been on infected farms, is tiny by comparison.
The limited information available suggests that deer behave much like sheep and cattle when they are infected with FMD: they are susceptible and, if infected, excrete FMD virus in similar quantities for a similar period, usually measured in days. A 1975 report concluded that they were unlikely to be important in the epidemiology of FMD in the UK because they do not contact livestock closely. The outbreaks in the New Forest in 1957, and in Rothbury, Northumberland in 1966, were both in areas frequented by deer. No action was taken against deer in either area, there is no evidence that they became infected, and they certainly did not infect domestic livestock when premises were restocked.
Although there have been many reports of infected deer in the present British epidemic, none have yet to be substantiated by isolation of virus or by serology. Deer from infected premises and areas in Devon, Cumbria, Ayrshire and Dumfries have been sampled, and all laboratory results have been negative even though lesions were described.
Research at Pirbright with five different species of deer (including red deer) has shown that there is no carrier status. The probability is that even if infection were introduced it would die out and that deer would not maintain the disease in the absence of infected domestic livestock. Until 1968 FMD was repeatedly introduced and then eradicated from British livestock, and no action was taken against feral deer. Failure to do so did not prevent eradication. The same is true of other European countries, and it is fair to say that historical epidemiological evidence provides no reason to believe that deer have any epidemiological significance in UK or Western Europe.
The density of feral deer in an area such as Exmoor will be lower than in a deer park, and the risks will also be lower. Risks cannot be entirely eliminated, however, there is no action that the Park Authority or anyone else can take to do so.
In summary, deer can contract FMD but may have little or no epidemiological significance. The greatest risk they face is direct contact with infected domestic animals: the evidence we have so far, though much too limited to be conclusive, is that this has not happened. Other risks are much lower, and the less direct the route the lower the risk. Cars and people who have not worked with, handled or been in contact with livestock, are unlikely to pose any significant risk of introducing infection to deer and other animals in an area where infection is not already present.