Oh my I hate to know you're having to deal with this. I did a little research and couldn't find anything about DE killing parasites outside the body. We are lifetime farmsteaders or homesteader if you prefer and have used DE for many years for fllies, mites, fleas, ants, and internal worming. In the garden, it has helped us with slugs as much as bowls of beer. When we fail to replace the DE after a heavy dew or rain we see some, but as soon as we put it out again it starts cutting them out. Good luck. If I run across any other info, I'll be sure to share it with you.