infectious disease-a disease that can be spread from person to person

noninfectious diseas-a disease that cannot be spread from person to person

chronic-diseases that last a long time

acute-diseases that last for only a short time

pathogen-an organism that causes disease

viruses-smallest pathogen, causes colds, flu, chicken pox, and measles

bacteria-one-celled living things that can cause disease

infection-the growth of pathogens somewhere in the body

contaminated water-water that has dangerous pathogens in it