Willett, who won his first major title at Augusta National in April, is set to represent Great Britain in Rio as golf returns to the Games for the first time since 1904.
However, as he contemplates the prospect of having more children after the birth of son Zachariah just 12 days before his Masters triumph, Willett admits to having concerns over Zika and its links to defects in newborn babies.
“We are monitoring it,” Willett told a press conference ahead of the BMW PGA Championship at Wentworth. “We’ve had an e-mail from the WHO [World Health Organisation] and we are keeping on top of it.
“It’s not great, is it? There’s going to be 500,000 people watching the Olympics and you have 11,000 athletes right in the heart of where it’s at.
“If it turns out that it would be a massive threat to myself or to Nic [his wife Nicole] or to the little man, then I probably wouldn’t go.
Willett added: “Family comes first. But as it stands at the minute, I think everything should be okay.
“We’re down to go and hopefully they can give us some proper guidelines as to how to keep it at bay and keep it under control so that it doesn’t ruin what could be potentially a fantastic Olympics.”
While former Masters and US PGA champion Vijay Singh and Australia’s Marc Leishman have already announced their withdrawal because of worries relating to the mosquito-borne virus, McIlroy has revealed he will keep an eye on developments in Brazil.
The world No 3, who became engaged to Erica Stoll last year, told the BBC: “I’ve been reading a lot of reports about Zika and there’s some articles saying it might be worse than what they’re saying.
“I have to monitor that situation because there’s going to be a point in time over the next couple of years where we’re going to have to think about starting a family and I don’t want anything to affect that.
‘’Right now I’m ready to go to the Olympics and go down to Rio and try to compete for a gold medal.
“I’m actually going to get my injections on Wednesday for all that so at least I’ll be immunised for whatever if I do get bitten by a mosquito down there.’’