11 August, 2017
Food poisoning has struck down Botswana's 400m medal hope Isaac Makwala at the IAAF World Championships now under way in London.
Justine Palframan 's campaign came to an end, however, in the 200m women's semi-finals, after she too took seventh position in her race in 23.21.
Van Niekerk, who also set the world record when winning Olympic gold in Rio previous year, was in imperious form, running a devastating final bend to finish in 43.98 seconds, easing up a full 15 metres from the line.
Makwala's quarantine period ended at 2pm yesterday and after a medical examination showed he was fit they had accepted a written request from his federation for him to race.
He might not have scooped the golden double he was aiming for, but he is still the first South African athlete to land two sprint medals at a single meet.
"Coming away with two medals, both a good colour - gold and silver - I think it's great for my career and another moment to be grateful for".
Botswana's Isaac Makwala was also struck down with the bug but given medical dispensation to withdraw from the 200m heats on Monday night.
Immediately after his race, he told BBC Sport that he was still heartbroken after missing out on a chance to contest for gold in his favored 400m and was "running with anger".
"It's just generalised assumptions because of the outbreak of sickness and he has just one of those symptoms", he said.
The IAAF added that "no athletes already qualified for the semifinal will be adversely affected".
"I wouldn't say it affected me, I just expected more from someone I've been competing against", said Van Niekerk, who ran 20.11 seconds.
"I arrived at the stadium today ready to run but I found a trap set there ... and denied entrance [government order by the way not IAAF]".
Botswana's Isaac Makwala, the fastest man in the event this year, missed out on a medal, coming fifth.
He booked his spot in the semis after a solo time trial in cold and wet conditions on Wednesday and then finished second in his semi, ensuring him the status of sentimental favourite for the final.
