Hi Myra,
Good for you, to check on that. Many people assume they can just plunk their ducks on a pond and ignore them.
And I have good news for you: Ducks are incredibly hardy and require no regular medical care. If you are providing them with fresh water, good nutrition, and plenty of exercise, then you may never have to use medications or veterinary care.
Ducks naturally run a very high temperature that discourages illness and worms, and they are generally extremely hardy. Their weak point is the legs and if you have an injury or disability, more often than not it will be in the legs. When something happens, most ducks will recover with just a little confinement and attention.
I have about 30 ducks and have never needed a vet. Most of my losses have been to predators, which is the biggest threat to a duck's welfare. I've lost a few ducklings to undetermined causes, but that is just how it goes when you raise a bunch of critters. I've also had some minor bouts with niacin deficiency and angel wing, all of which were quickly cleared up by correcting environmental/feeding conditions.
Welcome to BYC, and enjoy your duckies.