Below are the latest announcements:
Australia
Australia's Olympic Committee said no athletes have indicated they intended to withdraw, but it would "totally understand" if they did.
Britain
British Olympic Association Chairman Lord Sebastian Coe said none of the country's athletes were reluctant to go.
But British rower Andrew Triggs Hodge said his wife Eeke would not accompany him because of the "very real and frightening threat" posed by Zika.
Japan
Japan's Olympics Committee Chairman Tsunekazu Takeda said no athletes were thinking of "boycotting the Olympics".
Kenya
Kenya threatened to pull its elite runners and other athletes out of the Rio Olympics unless it got assurances they would not be exposed.
"Obviously, we are not going to risk taking Kenyans there if this Zika virus reaches epidemic levels," said the head of Kenya's Olympics committee, Kipchoge Keino, himself a Kenyan running great.
New Zealand
New Zealand's Olympics Committee issued a warning to its athletes and officials of the risks.
Any competitors who decide to opt out would receive the committee's "absolute support", a committee spokeswoman said.
United States
The United States Olympic Committee told sports federations that athletes and staff concerned for their health should consider not going to the Games.
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