RUNNERS who competed in a harrowing obstacle course in France have become violently ill, believed to have been caused by bacteria in the mud.

A record field of more than 8,000 entrants took part in the race on the Côte d’Azur in Nice last week.

The following day, at least 30 participants complained of diarrhoea, vomiting and fever.

That figure has now shot up to over 1,000.

The cause of the illness hasn’t been confirmed, but it’s possible the mud may have been contaminated with harmful bacteria from animal faeces.

Some of the participants recalled smelling horse manure at various points in the race.

Organisers of the Mud Day event addressed participants on the event’s web page, promising to do everything possible to determine the cause of the stomach upsets.

They said that there had been no need for hospitalisation.