Essential oil compounds, such as p-cymene, thymol, salicylaldehyde, tea tree oil, peppermint oil, cuminaldehyde, cinnamic acid, cinnamic alcohol, farnesal and farnesylacetone, especially 2-decenal and nerolidol when added to feed or drinking water to combat histomonas, a single cell protozoan organism that is an intestinal parasite infecting both vertebrates and invertebrates.
