DOCTORS have warned that outdoor sports enthusiasts are at risk from the deadly E coli 0157 bug if they get splashed with mud, after treating a young cyclist for the illness.

The bacteria, which lives in the gut of animals, is usually associated with food poisoning or drinking contaminated water.

However, clinicians at Aberdeen Royal Infirmary have revealed they treated a 23-year-old vegetarian for an E coli 0157 infection after he was admitted to the hospital suffering from vomiting, abdominal pain and bloody diarrhoea.

The young man said he had not eaten undercooked meat or vegetables. Nor had he spent time with livestock or visiting farms before falling ill.

However, on further questioning, the doctors say they learned that eight days before his symptoms began the man had competed in a cycling event along wet, muddy tracks in eastern Scotland.

He, along with other competitors, had removed the mudguards from his bicycle to reduce weight and mud and water had splashed his face during the race. It is thought that this was how he became infected with the bug, which can be found in animal faeces and farm slurry.

The cyclist, who has not been identified, recovered but the doctors have highlighted his case in medical publication the Journal of Infection Prevention.

Outdoor endurance events, both cycling and running, some with obstacle courses, have become increasing popular in recent years with many events being held across the country on weekends throughout the year.

Dr Robert Laing, consultant physician in Infectious Diseases and Internal Medicine at Aberdeen Royal Infirmary, co-authored the report.

He said: 'We know that E coli 0157 survives well in cattle faeces and this case highlights the possible risk to participants in sports that expose them to mud that may have been contaminated by animal faeces. Splashes to the face are likely to be particularly hazardous and efforts should be made to protect yourself from these as far as possible."

In 2012 three people contracted E coli 0157 infection, following a 12-mile 'Tough Mudder' event at Drumlanrig Castle, Dumfriesshire, which involved immersion or contact with mud. In 2013 a study of one of the world's largest mountain bike races - the 'Birkebeinerrittet' in Norway - found that when mudguards were attached to bikes, there were fewer cases of gastrointestinal illness.

In the Journal of Infection Prevention, the Aberdeen-based doctors write: "Sporting endeavours such as cycling and cross-country running events often take participants through such high-risk areas and may be an important cause of contact with E coli 0157:H7.

"This case highlights such exposure and should alert clinicians to the possibility of E coli 0157:H7 infection and the importance of individuals presenting with bloody diarrhoea with a history of participation in similar sporting or other events."

A Health Protection Scotland spokesman said: "Anyone taking part in outdoor sports such as running or cycling and that crosses areas that have recently been occupied by animals such as cattle or sheep should be aware of the risks of picking up a gastro-intestinal infection such as Vero cytotoxin-producing Escherichia coli (VTEC), more commonly referred to as E coli.

"One of the main risks to humans is from coming into contact directly or indirectly with contaminated animal faeces. Our advice would be to follow common sense principles and if you have contaminated hands or face, take care that this material does not get into your mouth and wash as soon as possible and certainly before eating."