At least 30 athletes and team members at the world athletics championships in Yunel Escobar Authentic Jersey London have been infected in a suspected outbreak of norovirus, public health officials have said. Several competitors were forced to withdraw from events in the first half of the tournament after suffering symptoms including vomiting. Nine people were still affected by Tuesday afternoon, the organising committee said.

The diagnosis comes after athletes and support staff from the Botswanan, German, Canadian, Irish and Puerto Rican teams staying at the Tower hotel, near Tower Bridge, were taken ill over several days. Some, according to reports, have been put into quarantine. 

Competition organisers said on Monday that the illnesses were a result of gastroenteritis, but Public Health England (PHE) on Tuesday said that laboratory tests had confirmed that two infections were caused by norovirus. The bug is easily spread, partly because it can survive for several days outside the body.

The Tower hotel has insisted that it was not the source of the outbreak. “We have worked collaboratively with the EHO [environmental health officer] and the IAAF [International Association of Athletics Federations] to http://www.authenticlosangelesangels.com/Rod-Carew-Jersey investigate the origins of the illness and can confirm that the hotel was not the source,” the hotel said in a statement. “We have followed strict hygiene protocol, ensuring that those affected are not in contact with other guests and all public areas have been thoroughly sanitised.”

Among those affected was Botswana’s Isaac Makwala, who was given medical dispensation to withdraw from the 200m heats on Monday after vomiting in the stadium medical room. On Tuesday evening the IAAF said Makwala would also miss the 400m sprint final, where he had been expected to win a podium place. “Isaac Makwala was withdrawn from the men’s 400m [final] due to a medical condition on the instruction of the IAAF medical delegate,” an IAAF bulletin read.

But a distressed Makwala Jay Bruce Youth Jersey turned up at the stadium, wearing his blue Botswana tracksuit top and wireless headphones, attempting to gain access to the warm-up track to prepare for the 400m. His access was blocked by two security guards who inspected the accreditation pass round his neck then escorted him to the office of the IAAF on the stadium site before taking him back to the hotel.

Former world and Olympic champion Michael Johnson said the IAAF had made a hash of the situation and even suggested they could be accused of deliberately excluding Makwala to give his chief rival Wayde van Niekerk the best chance of winning.

“This is going to be one of those situations where the IAAF is going to realise it’s got it horribly wrong one way or the other,” said Johnson, “either by disqualifying this athlete from competition unnecessarily, or by not communicating clearly to him and his team why they’ve chosen to disqualify him. Does this go across the board and apply to all athletes? What are the criteria? If you collapse you’re OK but if you vomit you’re not OK?

“There’s a lot of inconsistency here and the elephant in the room is that Wayde van Nierkerk is an IAAF favourite,” added Johnson, “a fan favourite, a favourite of everyone, an Olympic champion, a world record holder, a world champion, and now the only challenger has been pulled out of both of those races. Conspiracy theories abound.”

Ireland’s Thomas Barr was forced to withdraw from the 200m hurdles semi-final on Monday http://www.authenticnewyorkmets.com/Jeurys-Familia-Jersey night. “I wasn’t feeling great yesterday evening, and later in the night I was hit with a bout of gastroenteritis,” he said. “My whole year has been focused on the world championships, and to not be able to go out and compete for Ireland today is beyond disappointing.”At least seven Canadians were affected, including Eric Gillis, who was forced to drop out of Sunday’s marathon after about 20 miles. “I was one of the athletes in quarantine,” the Canadian sprinter Aaron Brown said. “I was in my room the entire day in the dark. I was like a vampire. I was holding my stomach the entire night.”

Falcon Sedimo, chief executive of the Botswana national sports commission, said he did not blame the British hosts for the outbreak. “We can’t blame anybody because, for starters, we don’t know how this came about,” he said as he walked with two team officials close to the Tower hotel.

“It’s not the first time we have been to Britain – some of us have studied here, we were here for the Olympics in 2012 – all of us have been in the UK many times before and we have not fallen sick. This is the first time that something of this kind has happened.”

Makwala was not the only Botswana team member who had been struck with the bug, Sedimo said. Onkabetse Nkobolo, another 400m sprinter, was also affected, but he had recovered quickly and was back in training on Tuesday.

Sedimo said he could not say whether a floor of the hotel had been “quarantined”, as reports have suggested. “Obviously, as soon as this has come to light the impression that we have is that it has been taken care of,” he added. “We remain hopeful that all will be OK and it shouldn’t spread to affect other team members.”

The man told his colleagues that the athlete, who was not named in the fragment of overheard conversation, had not suffered any other symptoms. When the Guardian approached for comment the man referred questions to the IAAF press office.