Jay I know people feel the blackworms offered for sale in the hobby are the same as tubifex but Blackworms are much fatter and a different color and have different "mannerisms" and grow in different places. Tubifex are typically found in drainage ditches and horse feeding troughs while blackworms in the hobby are grown in California commercially in pools.
I don't know if the scientific name is the same but if it is, the people who name such things need to call the school they went to and see if they can get their money back as blackworms in this hobby and tubifex are not the same at all. Just my opinion of course as always.
I can't get blackworms here so I grow whiteworms which live in damp soil and live for 5 days in saltwater. I actually tried it.
If Mycobacteria is found in blackworms it doesn't seem to affect my fish which have been fed with them for upwards of 60 years. No problems yet but maybe because my fish seem to be immune to just about everything they are also immune to blackworm diseases.
In this instance, the Mycobacterium was confirmed as coming from the California blackworms, both in the worms, as well as the dead fish themselves through culturing (something that is rarely done because Myco grows so slowly and labs don't take the time).
True tubifex worms are more of an east coast thing, collected locally, When most people say "tubifex", it is more often blackworms, Lumbriculus variegatus and not the red worm, Tubifex tubifex.