Only in some case, a "nosode", i.e a trace of the disease, is used. But it is not systematic. For example, oscillococcinum [0] which is sold as a flu remedy, is famous for containing some cells from a duck liver.
If I remember correctly a single duck is raised every year, and due to the dilution, is enough to produce the millions of dose.
I am not sure what makes more sense, the nosode or the duck liver...