Mumps, Polio, and Rabies are all caused by viruses. Mumps virus causes salivary gland inflammation, Poliovirus attacks the nervous system causing paralysis, and Rabies virus affects the brain. Dysentery is primarily caused by bacteria (Shigella) or protozoa (Entamoeba histolytica), not by viruses - it involves intestinal inflammation and bloody diarrhea.