Libertybelle got me to looking at some of these things again after thinking about poisonous snails (passed through in reading about some of these over the years.)
Always wash your hands after handling snails and other tank water stuff for that matter, and don't eat slugs.
It isn't really that terrifying or something to give you nightmares, but be careful and use standard sanitation practices, just like picking up small animal pets (salmonella), and not letting dogs lick your mouth or sores/ open wounds (Capnocytophaga canimorsus)... (oh we people really love our animals, lol.)
And then there are zoonotic diseases.
cone snail / Conus parius - don't play with these guys
And their shell-less relatives slugs
Rat lungworm disease (from rodents like rats)
Watch out for bird droppings on picnic and patio and kids play outside tables and homegrown veggies /fruits as well.
and this was the Assassin snail topic which libertybelle was mentioning in her thread about them...
My thoughts and how this thread started so I wasn't hijacking libertybelle's.
"... of Assassin snails, which at the Aquarium Club meeting I was listening to a group of seasoned hobbyists which speculated the ability of a neurotoxin from the snails. Whereas, for instance why would a huge snail like a Mystery snail get taken out by one... little, tiny Assassin?
So one possible rumor of their abilities. Which also makes me concerned about putting my hand in a tank with them, lol or not lol - not sure.
It was, what seemed as I had walked up to the group of people talking, that someone else in the aquarium field had proposed this consideration. Referring to "he" , as I missed the name. After listening to the back and forth for a few minutes, I was distracted by someone else and went off in the other direction, without further details.
Though they had mentioned there were types of Mollusks (Conus parius SW
cone snail for one), which have special abilities for capturing /eating their prey."
In general I haven't seen any worse dangers from keeping Ramshorn snails in my tanks, than keeping a dog or cat (toxoplasmosis). All pets could pose some kind of health risk.
The best thing is to know how to reduce the risks.