A mild bug which can knock athletes off their stride could be picked up in the "quite stressful environment" of the Games, according to Dr Ian McCurdie, the British Olympic Association (BOA) chief medical officer.
It could hamper an athletes' chances of performing at their best, he said.
On whether this means shaking hands should be off-limits, he said: "I think, within reason, yes".
Olympic gold-medalist and swimmer Duncan Goodhew told ITV Daybreak he though the advice was sound: "You've got one minute in four years to be good ... and so you want to do everything you can to make sure you're fit and healthy."
The advice is part of a detailed package of health and resilience issues which the BOA has looked at ahead of the Games.
Tips for the 550-strong team of athletes and 450 support staff who will work with them include regular handwashing and use of a special protective hand foam as an extra barrier.
Dr McCurdie said: "Almost certainly, I believe, the greatest threat to performance is illness and possibly injury.
"At an Olympic Games or any major event the performance impact of becoming ill or even feeling a little bit ill can be significant."
He notes that the Olympic environment is "a pretty hostile one" and that it will be a first-time experience for many athletes and support staff.