T.B. is correct in that pinworms are typically not a serious issue in snakes and are relatively easy to treat. Fenbendazole is usually dosed orally at 25 mg/kg three separate times, each dose two weeks apart. Pins have a direct life cycle and so do not require an intermediate host. The units need to be kept exceptionally clean of feces during the treatment period to avoid re-infestation.
Another issue that should be checked is the feces of any feeder animals, especially if feeding rodents. While pins are class specific and mammalian pinworms cannot infect reptiles, the rodent pinworm eggs can pass through the snake intact after feeding, and cause it to appear that the snake has a pinworm infestation. It is best to have fecals run on both snake and feeders, and go ahead and treat the snake anyway if eggs are found in both. This unless of course you can rule out the snake issue by changing to pinworm free feeders.
Kelly