One, five billion people around the world are living with at least one of these worm species. They can invade hosts cells, tissues, and therefore cause damage. And they can also compete for nutrients like b 12, for examle ju blood, or blood. If you had a handful of them, would be no issue. But if you had thousands, that's and they're hulling a lot of blood out of you got,. ah, then you're going to have issues.