Don't get caught up in it. Meliodiosis is caused by Burkholderia pseudomallei, a typically soil-dwelling bacteria (not at all related to Giardia). It's actually quite widely spread but you only occasionally see outbreaks in the US/Canada. I think the point was that palytoxin poisoning is as rare as meliodiosis. Maybe, I don't know ¯\_(ツ)_/¯I better look meliodosis up, I'm unfamiliar with that term!
Edit: Meliodosis does not appear to really be a problem where I live (Canada.) Confused how it would relate to my aquarium as it seems to work more like the freshwater parasite giardia than like anything dwelling in saltwater.

