The 32-year-old, who captured the first major title of his career at Oakmont last month, said his concerns "could not be ignored".

His decision not to play means three of the world's top four players will not be present at Rio 2016, following the confirmed absentees of Northern Ireland's Rory McIlory and Australian Jason Day. 

Both also said that Zika was the reason for their withdrawal, with Johnson's decision a fresh blow for a sport which is returning to the Olympic programme for the first time since 1904.

The mosquito carried virus - declared a global emergency by the World Health Organization (WHO) - has been spreading through the Americas with its epicentre in Brazil.

Symptoms can include fevers, rashes, joint pain, eye redness and conjunctivitis, but it is of particular concern to pregnant women who have been advised not to travel due to a link with microcephaly - which causes babies to be born with small heads and under-developed brains.

"As an athlete, I can think of no greater honour than representing the United States in the Olympic Games," Johnson said.

"Paulina [Johnson's fiancee] and I plan to have more children in the near future, and I feel it would be irresponsible to put myself, her or our family at risk.

"While I am sure some will be critical of my decision, my hope is that most will understand and support it.

"This was not an easy decision for me, but my concerns about the Zika virus cannot be ignored."

Other golfers to have withdrawn include South Africa's Branden Grace, Fiji's Vijay Singh, Australian Marc Leishman, Zimbabwe's Brendon de Jonge and Japan's Hideki Matsuyama, while South Africa's Lee-Anne Pace will not play in the women's tournament.

Many have been critical of the decisions, however, with the high number of golf withdrawals compared with other sports leading to suggestions that the players merely see the Rio 2016 tournament as an inconvenience in an already hectic schedule and are using Zika as an excuse. 

Most golfers would still prioritise a major title over Olympic gold with the exodus leading to debate about whether golf should be part of the Games programme at all.

The seriousness of Zika has been downplayed, too, with the virus said to be less prevalent in the cooler Brazilian months of August and September when the Olympics and Paralympics will take place.

In an exclusive insidethegames blog, Brazilian Health Minister Ricardo Barros claimed the Games will only present 0.25 per cent of all travels to Zika-affected areas worldwide.

In a further bid to ease fears, Rio 2016 has signed an official insect repellent partner, SC Johnson’s OFF! brand.

Thousands of bottles will be given to athletes, staff and volunteers as part of the deal.

The view from golf has not been completely negative, however, with Spain's Sergio Garcia tweeting: "I know there are some dangers but representing Spain, trying to make golf grow and becoming an Olympian are too important so I’ll be at [the] Olympics."