The health concerns I have heard about are all related to the open water events. Athletes have been getting sick from swimming, sailing, rowing, etc through the bay.
If Zika is so threatening there should be a travel restriction already in place. Just stay around the Olympic venue sites which have already been heavily treated with insecticide to control breeding. It’s going to be winter anyway, so the risk is going to be extremely low in terms of mosquito transmission. There is definitely a greater risk of the flu or food poisoning not to mention swimming around open sewage.
Yeah you dont want to be a aater sport athlete down there in Rio. Good God just swim in a porta potty, thats what its gonna be like.