Take a fecal sample to your vet when they make you one. (And have a herp vet lined up before you get them. Get references if possible.) If the vet finds parasites, he'll treat them. Not too expensive per dose, and the fecals shouldn't set you back too far. If they're from the same source, you can do one fecal and treat them all if anything is found. If nothing is found on the first fecal, get another one done in two weeks or next time they go poo. This will help you be sure of not having any parasites, as most common parasites have a two week life cycle.