the bbc news at six. 0rganisers of the world athletics championships at the london stadium are trying to limit the spread of the norovirus which has already affected dozens of competitors and staff. one of the highest profile casualties is botswana s isaac makwala a favourite in the two hundred and four hundred metre races. athletes from germany, canada and ireland who ve been staying at the same hotel have also been affected but officials from public health england say it is not the source of the outbreak. here s our sports editor dan roan. this is the time when the world s best athletes should be concentrating on their rivals. instead these competitors and coaches today found themselves at the centre of a suspected outbreak of the highly contagious vomiting bug norovirus at this team hotel. for botswana, issac makwala! yesterday the world s best 200 metre runner, issac makwala, was forced to withdraw from the event. the botswanan medal prospect one of 30 athletes and su