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).
One of the stars affected was Botswana's Isaac Makwala, who had to withdraw from Tuesday's men's 400m final on medical grounds.
In a statement issued on Tuesday, the sport's governing body, the IAAF, said that Makwala had to be quarantined in his room for 48 hours, a period which would end at 14:00 BST on August 9.
IAAF's statement read: "The team doctor, team leader and team physio had been informed following the medical examination that the athlete should be quarantined for 48 hours and would therefore be missing the 400m final on Tuesday.
"The IAAF is very sorry that the hard work and talent of Isaac Makwala won't be on display but we have to think of the welfare of all athletes."
The athlete told reporters Tuesday that he was fit to run, but hours before the 400m final he was refused entry into the London Stadium.
He said on Facebook that he had been the victim of a "government trap."
"I still maintain I am not sick and have never been tested by any Doctor. I shall rise again," he wrote.
Fastest 200m of the year
Makwala, one of the favorites for the 200m and 400m world titles prior to the championships, had to withdraw from the 200m heats Monday after a reported bout of food poisoning.
Makwala, 30, had posted the quickest 200m time of the season (19.77 seconds) coming into these championships and was expected to challenge 400m Olympic champion Wayde van Niekerk over both distances in England's capital.
In a statement on his Facebook page on Monday,
Makwala said: "According to IAAF medics I am apparently suffering from food poisoning which has affected several other athletes in the athletes' hotel."
Recovery expected without treatment
Ireland's Thomas Barr withdrew from the 400m semifinals, while German and Canadian athletes also staying at The Tower Hotel near Tower Bridge have reportedly been affected too.
In a statement to CNN, Dr Deborah Turbitt, Public Health England (PHE) London deputy director for health protection, said: "We have so far been made aware of approximately 30 people reporting illness and two of these cases have been confirmed as norovirus by laboratory testing.
"PHE has been working closely with British Athletics and the hotel to provide infection control advice to limit the spread of illness."
Public Health England said most people made a full recovery from the illness -- often caught through close contact with someone carrying the virus or by touching contaminated surfaces -- within one or two days without treatment.
Hotel 'not source of the illness'
A spokesperson for The Tower Hotel told CNN it was "not the source of the illness," adding that the hotel was working closely with the sport's governing body, the IAAF, and environmental health officers to investigate the origins of the outbreak.
"We can confirm that regretfully a small number of our guests have been suffering from an illness," a statement read.
"We have followed strict hygiene protocol, ensuring that those affected are not in contact with other guests and all public areas have been thoroughly sanitized.
"We continue to liaise with the medical authorities and the IAAF to ensure the comfort of those guests affected and the health and well being of all our guests remains a priority."
Working to ensure situation is contained
A statement issued by the Local Organizing Committee (LOC) said they had been working with Public Health England to ensure the situation was "managed and contained."
"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.
Under IAAF rules, Makwala would not normally be allowed to compete again at the championships after pulling out of an event, but because he missed the heats on medical advice he is expected to able to run, if fit.