A number of teams staying at one of the official London hotels of the World Athletics Championships have been affected by a stomach virus, the local organising committee said on Monday (local time).
One of the most high-profile victims was reported to be Isaac Makwala of Botswana, one of the favourite for Tuesday's 400 metres final, who was due to race in the first round of the 200 metres on Monday but did not start.
He was withdrawn due to "an unspecified medical condition" by an IAAF medical delegate, though it was not immediately confirmed if he was staying at the hotel in question.
The London 2017 organisers released a statement later on Monday saying that a number of team members had reported numerous cases of gastroenteritis at their hotel. "There have been a number of cases of gastroenteritis reported by team members residing within one of the official team hotels for the World Championships," the statement said.
"Those affected have been supported by both team and LOC medical staff, in addition we have been working with Public Health England to ensure the situation is managed and contained.
"As a result, further advice and guidelines have been issued to team doctors and support staff - standard procedure for such an occurrence where a number of teams are occupying championship accommodation."
