I think the most telling part of this infection was that good 80% of rats carry them and only a few get sick. From memory I think +20% of rats in pet stores (more with in those with less healthcare :)) in the US carry them.
When they did research on this they found that only rats with a faulty thymus got ill. Apparently it is the thymus that creates immune response to kill their eggs and stop the hatching...got Lugol's?
Also that first sentence should have included Lead, love Lead lives off Bile. All in all a very nasty critter and no single frequency will kill it one has to sweep and quite a sweep...