Deer health project finds very low levels of harmful E. coli O157 strain in wild deer in Scotland

A project undertaken by the Moredun Research Institute and the University of Edinburgh into harmful E. coli O157 bacteria in Scotland’s wild deer has established that the bacteria has a low prevalence in deer of less than 0.3 per cent.

Richard Cooke, Chairman, LDNS, says:

“When we signed up to the project it was in part a leap of faith and we hoped that science would show that the occurrence of this bug in our wild deer species is extremely low, and this has turned out to be the case. Whilst we cannot make comparisons with the level in livestock or other foods, or comment on the level of risk to human health, we can certainly take comfort from this result whilst at the same time encouraging all involved in the sector to continue to be vigilant and observe Best Practice at all times to keep incidence to an absolute minimum.”

The study, funded by the Scottish Government and Food Standards Scotland, was carried out following the outbreak of E. coli O157 infection in people linked to the consumption of venison products in 2015. The bacteria, which is shed in animal faeces, causes disease due to the production of Shiga toxin and is most severe in very young or elderly people. The research set out to determine what the levels of E. coli O157 in wild deer in Scotland are and how these bacteria might be transferred to meat during the production of venison.

The research was based on the collection and testing of faecal samples from all species of wild deer in Scotland (red, roe, sika and fallow) and covered all of Scotland’s regions where wild deer are present. Through working alongside ADMG, LDNS and Forest Enterprise Scotland, a total of 1087 samples were received of which E. coli O157 was found to be present in three. Two positive samples came from red deer and one from a sika deer.

Despite these low numbers, deer managers and processors are being urged to continue to do everything within their control, from the point of cull to the end product reaching the consumer, to minimise the risk of faecal contamination of the carcass.

Dr Tom McNeilly, the Moredun Research Institute, who led the study, says:

“This project established that prevalence of E. coli O157 in Scottish wild deer is low and suggests that deer are not a major reservoir of the bacteria. Nevertheless, as E. coli O157 was found in a small number of deer and the gene for the toxin was present in a number of other samples, care should be taken to ensure minimum contamination of the deer carcass during processing. We would like to thank the deer industry and Forest Enterprise Scotland who have been fantastically supportive of the project.”

Dr Jacqui McElhiney, Head of Food Protection, Science and Surveillance at Food Standards Scotland said:

“We commissioned this piece of work alongside the Scottish Government in response to the 2015 E. coli O157 outbreak in order to improve our understanding of the risks of contamination of venison meat in Scotland. The results of this part of the survey show that the levels in deer faeces are low, but when E. coli O157 is found, it has the potential to cause severe disease if it is transferred onto the meat. The findings will support guidance that will help producers to prevent contamination.

“We would also like to remind consumers to ensure their venison is cooked thoroughly and that they follow good hygiene practices when handling raw meat to avoid the risks of food poisoning”.

Bill Bewsher, Chairman, the Scottish Venison Partnership, says:

“This has been an important piece of work for Scotland’s venison sector, given the new strategy for Scottish venison launched by Government in September and its increasing popularity.

“We will continue to urge those who manage deer, and those who process venison, to take all necessary steps to ensure that the processed product reaches the market in the safest possible condition, with a reminder to consumers that proper cooking will eliminate any residual risk.”

Partners in the Scottish Deer Health Survey include:
Association of Deer Management Groups
Lowland Deer Network Scotland
Scottish Venison Partnership
Scottish Quality Wild Venison

• E. coli bacteria are very common in the environment, with many types of E. coli living in the guts of mammals. Some types of E. coli can cause disease, some are harmless and can even be beneficial.
• E. coli O157 are a particular type of E. coli that can cause human disease as a result of the Shiga toxins they produce during infection. Other types of E. coli other than E. coli O157 can also produce the toxin and can also cause human disease.
• Human infections can cause serious illness or even death, particularly in very young or elderly people.
• E. coli O157 can be carried by cattle and other ruminants, including deer and sheep, without affecting them in any way. Shedding of the bacteria from ruminants tends to be sporadic, meaning an animal that is positive for E. coli O157 on any particular day can be negative on another day.