I think it is Frank Indiviglio who has recommended feeder fish as safe for large frogs, so its hard to argue with that... As I commented earlier, all wild frogs (and probably many captives) carry a parasite load. For healthy frogs, in unstressed conditions, this is not an issue.
However, for me, fungi such as chytrid are far more of a concern than intestinal parasites. Some studies suggest that fish from chytrid-carrying ponds/hatcheries/lakes should be considered contaminated (and likely carriers of chytrid). Hatcheries do not test for chytrid because it does not affect fish and amphibians are regular inhabitants of hatchery ponds.
I would be cautious...