England’s public health body admitted it had been notified of 30 cases in people associated with the championships, with high-profile stars among them.
In a statement, the Local Organising Committee confirmed that some teams’ medical services had to provide medical care to athletes staying at London’s Tower Hotel.
Among those taken ill were Irish athlete Thomas Barr, who withdrew from the 400m hurdles semi-final, and Botswana’s Isaac Makwala, a favorite for a medal in the 400m, who withdrew from the 200m heats.
“According to IAAF medics I am apparently suffering from food poisoning which has affected several other athletes”, Makwala wrote.
The organisers of the global showpiece, being staged at the London Stadium, announced late on Monday that a number of athletes staying at the same official hotel have suffered from gastroenteritis.
Per BBC Sport, IAAF spokeswoman Jackie Brock-Doyle said health and safety protocols had been followed after the outbreak at the Tower Hotel.
“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”, the statement read. That has also been confirmed by Public Health England.
Makwala, 30, was one of the favourites for the 200m and, without a valid reason for withdrawing, he could have been disqualified from the 400m.
Makwala was expected to be the main challenger to Wayde van Niekerek in both the 200 and the 400.
He was withdrawn due to “an unspecified medical condition” by an IAAF medical delegate, though it was not immediately confirmed if he was staying at the hotel in question.
Approximately 30 people have fallen ill, with laboratory tests confirming two of those cases as the norovirus – an unpleasant but rarely serious stomach bug which causes gastroenteritis (diarrhea and vomiting).
A person with gastroenteritis is most infectious from when their symptoms start until a couple of days after all their symptoms have gone.