Yes, leos can have internal parasites, most of the time they'll only pass the microscopic eggs that you can't see. However, with heavy infestation, it is possible that they'll pass the worm whole. I've seen it once with one of my gecko; it's fatal if left untreated.
You should take its stool to the vet to get it checked first, when collecting it, try not to contaminate it with any matter, not even water, nor let it dry up. Leos often defecate at night-time, you can put the stool in a zip-lock bag or something, and put that in the fridge, then take that to the vet the next day. It is best to get the stool to the vet within 24 hours.
Hope this helps.