What are some examples of parasitism?
Classical instances are the parasites of humans (host), as the trypanosome that causes Chagas' disease, the HIV virus (AIDS), the bacteria that causes tuberculosis, the schistosome that causes schistosomiasis, the hookworms, etc. Other instances are: tree (host) and parasitic helminths (parasite), dog (host) and lice (parasite), cattle (host) and tick (parasite), etc.