I got some magenta mystery snails on AB a while ago. Thank God I didn't put them with my Discus or Angels. I cured what they carried quickly but not until I'd lost several Rainbows.
Put a sacrificial lamb in a tank with them before you add them to your main tanks.
Mine were Magenta Mystery Snail. They are really quite beautiful. I'll send you some free, but even though the pathogens should be gone from them, I'd still use a hero fish.