My understanding is that no pathogen or parasite is able to become immune to chlorine dioxide (MMS), as long as it is anaerobic and acidic.

Jim Humle, is his book, says its like trying to get immune to handgrenades. It just isn't possible.

I also seem to recall him saying that, in 70(?) years of industrial application of chlorine dioxide, no pathogen has become immune to it.
Someone will correct me about the exact number.

In short: No, you need not worry about your parasites becoming immune to Miracle-Mineral-Supplement .

At least, this is what we are told. I have no way of actually validating this, obviously.