His next plan is to infect the entire populace in his territory with parasites that uses humans as vectors, starting with the class/caste with the worst hygiene and living conditions, and likely most diseases to spread? Sounds like it can't go wrong.
That said, I am unsure how infectious this kind of route is (I just know that it is often mentioned as the reason we use cow-dung as opposed to humans), and if they take care in cooking all food first it is very likely to be perfectly fine (so no salads).