Treating Hookworms in Amphibians?

I keep captive bred newts. One of my alpine newts(A. Apaunus) was observed with a long white worm hanging from its cloaca. I took fecal sample to a local vet whom diagnosed hookworms.
Some advice has been to treat topically(on the skin) – placing newt in a terrestrial environment – less likely overdose -with fenbendazole.
Another opinion was that it would be better to use Ivermectin – also topically.
A lot of newt enthusiasts say don’t treat at all.
The newts are eating well, but appear fat, bloated, as if full of worms – but who knows?
The other question is how did they get the worms??? I am assuming ingested from earthworms???
Any experience on this matter is greatly appreciated!

Thanks!
Tony
317-709-2888

The vet found a nematode parasite in my toad's stool although she didn't strike either of us as unhealthy-- her skin and eyes are clear, nothing odd in her belly, and she definitely doesn't lack an appetite. The vet thought it was a hookworm at first, but found it was a nematode of some kind.

She prescribed an ivermectin solution where 1 mL is diluted into 1L of water and the toad bathes in it for about 15-20 minutes once a week for 6 weeks. Little Miss has her next bath this Thursday. I just cleaned out her toad carrier and put the solution in there because that way she'd have a sufficient soak but could hop around and not be in danger of drowning. Did the vet advise topical application or a medicated bath for the newt?

Hookworms and nematodes can come from any number of things-- but contaminated water namely.