Understood. Again, though, the liability waiver is the real issue here. It's called a liability waiver because you waive any liability that they might otherwise have. It would have liability for conditions that it knows exist or reasonably knows could exist and that it does not take reasonable action to prevent or warn you of.
As with any business institution, operators of gyms or health clubs owe a duty of reasonable care to its members with regards ***** ***** premises. The gym staff is required to inspect the facilities for the purpose of discovering conditions that may be dangerous to its patrons. According to the tort principles of negligence, a failure to correct dangerous conditions or warn members of dangerous conditions could result in legal liability for the operator. In order to recover under a negligence theory, the patron would need to prove that the gym operator’s failure to inspect the premises was the actual cause of their injuries.
Again, if there's a liability waiver, you're going to have to get around that first. You'd have to show that the waiver is too vague to be a proper waiver of liability (which is very hard). To do so, you'd pretty much need a waiver that has one line or so that says that they're not responsible for anything, etc... But even if you do that, or there's no waiver, you'd have to establish the connection between the fungal infection and the YMCA. That is, that it was the conditions at the YMCA that caused the infection (and not some other place). This could be difficult, and might require that you have biologists trace the specific strain to the YMCA, or at least show others that have had the same infection. So it's not as easy as it might seem.
The best thing to do would be to send them a demand letter, and asking if they have an insurance carrier that could process a claim that you have against them for this. That might be the easiest way to see if they can produce the liability waiver and further see what they might say about whether or not they had other infections. It's an uphill battle, as you can see, especially if there's such a waiver. If there's no waiver, then you should at least seek an attorney. But if there is, it's probably not worth pursuing anymore.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (3 or more stars). Look for the stars on your screen (★★★★★). Thank you, ***** ***** luck to you!