London School of Hygiene & Tropical Medicine

So how much of a risk does Zika pose to competitors and those travelling to watch them compete in Rio? Jimmy Whitworth, Professor of International Public Health explains:

"Rory Mcllroy has made a personal decision not to attend the Rio Olympics. That is as it should be, we do not know his personal circumstances and we should respect his decision.

"Golf courses would not be particularly dangerous places for getting infected with Zika. The mosquitos involved in transmitting the infection live around houses and rarely fly more than 50 metres from the breeding sites.

"For most people Zika virus causes a mild illness, often not even clinically apparent. If you do become ill you will be fully recovered in a week or so. Rarely complications such as Guillain-Barré syndrome may occur, but we should put this into perspective. This syndrome is as common or commoner after ordinary gut infections, such as Campylobacter, which are likely to be more common in Rio than Zika anyway. The most credible estimates suggest no more than 10-20 infections with Zika among the half a million athletes and visitors going to Brazil for the Olympics.

"For couples wanting to get pregnant or thinking of becoming pregnant there is a different balance of risks because of the dangers of microcephaly and congenital Zika syndrome. There are also now reports of a small number of cases being transmitted sexually.

"If a woman is pregnant, medical advice would be not to travel to Rio. If she is thinking of becoming pregnant, then she and her partner should delay conception for two months after returning and use barrier methods of protection. In the unlikely event of a woman or her partner of getting infected with Zika, they should delay pregnancy for six months, by which time all traces of Zika infection will have been cleared from the body.

"It's important all travellers follow public health advice before travelling and while abroad."