A reader asked about this. Here is what I found. If you know or
find anything more helpful, please, let me know, so I can add it here.
I have scanned my brain and some literature (including Frye), and
there is not much about leeches/flukes, except the following:
1) They can be seasonal
2) If there aren't too many on the animal, or if they aren't too big,
they are reasonably harmless (bothersome).
3) They can transmit diseases and infections.
As for getting rid of them, there were few directions, but you can
try the following:
1) Pick them off.
2) Soak animals who can take it (like turtles) in salt water.
3) Completely desinfect any tanks (including the gravel!). I have
used bleach to kill flukes in my aquariums once. Worked great.
4) Let animals who can take it dry off.
(So, the trick is to dehydrate the flukes/leeches)
5) Add 1 teaspoon of salt per gallon of water to the tank/pond. Make sure all the
inhabitants won't mind (most won't, but check it out, especially for the
frogs. I know most fish and turtles won't mind; dunno about frogs.)