| A | B |
| antibiotic | a substance, such as penicillin, that kills bacteria or slows their growth without harming body cells |
| infection | the occurrence of a disease caused by the presence of a living thing, such as bacteria, in the body |
| immunity | the body's ability to destroy pathogens before they can cause disease |
| antigen | a substance that stimulates the production of an antibody |
| epidemic | An outbreak of a contagious disease that spreads rapidly |
| antibody | a protein produced by a B cell of the immune system that destroys pathogens |
| pathogen | an organism that causes disease |
| vaccine | a substance containing pathogens that have been weakened or killed and triggers the immune system into action |
| B cell | a lymphocyte that produces antibodies to destroy a specific pathogen |
| T cell | a lymphocyte that destroys a pathogen directly. |
| allergy | a disorder in which the immune system is overly sensitive to a foreign substance |
| communicable disease | a disease that is transmitted from one infected individual to another individual |