I don't know that bloodworms would be hosts to camallanus. It is a very fair question however.

What little I've read does implicate various copepods. Burgess' magazine article intimates that each species of Camallanus has one or two specific copepod species which would be the host for them in the stage when they weren't in fish.

My guess is that if they were raised in a fish free pond or tub, they wouldn't have opportunity to contact Camallanus. The answer might be found by way of looking for parasites for Chironomid larvae or Chironomus. That genus of insect has also been called Tendipes. I'm a little confused as to what the proper genus is. Masters' Encyclopedia of Live Foods (1975) suggests that Chironomus used to be used, but that the proper name was then Tendipes. However one finds a lot of more recent referances to Chironomus. Others may not have agreed with Charles Masters.

Masters doesn't warn about them as vectors (carriers) of disease. If they are frozen, I would think they would be even less of a threat.

Decaying bloodworms in a tank can be a problem. So feed only as many as can be - and are - consumed.

I appreciate the wisdom of your question. I will try and look some more at the few pieces of info I might have (somewhere). That is also a great question for the Live Foods Mailing List. If you don't post it there, I will. :)

Nature being what it is, there are likely to be parasites which prey on bloodworms. Could there be something they could transfer to fish? Maybe. Just because a backyard food culturer hasn't heard of it, hardly means such a beastie doesn't exist. However again if the bloodworms or other food organism is raised away from fish (and pooping sea birds) ther risk is really minimal.