Welcome to Beemaster! As for how to stop diseases and parasites, you've got to know what they are to know how to stop them. There's no such thing as "hive worms" so I can't tell you how to avoid them. Start out by reading a good beekeeping book like Backyard Beekeeper from Kim Flottum to get a good understanding of what's what and what diseases look like and how to deal with them. There are also beekeeping techniques (or lack thereof) that can cause hives to exhibit the conditions you're concerned about too.