When I feel I don’t have enough information, I usually communicate with the guest that Is requesting to stay, and ask what I would like to know. In this case I don’t know what you mean by ‘risks’ as clearly this illness from a cursory glance involves mainly fatigue and other issues of a non- life threatening nature, but I would certainly go ahead and ask how capable the guest is of getting around if you are worried about having to be of assistance to someone who is sick.
A couple of things do stand out, although I would have to see the message to be sure, and that is the idea of telling a potential host about your illness. It would be odd to tell a host unless you are expecting something more than the usual guest, such as extra care, help up and down stairs, and help with luggage - even getting meals. This absolutely needs to be understood in advance, not just mentioned briefly. For instance, I couldn’t help someone to get up stairs, nor do I like to avail myself of luggage unless the guest packs appropriately, due to having issues of my own. Obviously a guest can’t just assume because they have mentioned they are ill that you will become their carer for a couple of days, as that is a different thing entirely from what they are paying for. And you should absolutely know in advance exactly what they might expect after you explain your layout. If you’re big and strong and have the time to spare, you might enjoy helping someone out, but others may not be able to at all. And if it is a matter of help with mobility, weight is an issue - it is important to know what you are dealing with.
Personally, I have a lot of issues with pain and illness, but I have never mentioned it to a host! The only two reasons I can come up with are the one above (wanting extra help/carer), or desiring attention for being sick. That last one is a long shot, but there are weirdos out there.
Always enter into dialog until you feel you are clear on everything. There is no harm in asking how well they are presently and if they can manage their own luggage and getting up stairs etc, or if they will require help. You should know these things in advance. It would be odd to mention being sick for no reason whatsoever, so worth exploring IMO
All the best!