Yes, one way to ensure the next generation lives is to absorb heavy metals then release them during death weakening the host enough for the kids to take hold.
F.Buskii appears to use Lead, Hulda just said Tapeworms use Uranium and we know Lyme uses Mercury...perhaps some roundworms as well...
So when your local nutcake tells you parasites are good for you because they absorb all that stuff and protect you then think again. First most of that stuff wouldn't have been absorbed in the first place and second they do it to keep a stranglehold on you, not for your benefit...