| A | B |
|---|
| disease | an illness; condition that keeps the body from feeling or working well |
| symptom | a sign of a disease |
| germ | a tiny particle or living thing that can cause disease |
| bacteria | one-celled living things |
| virus | a tiny particle, smaller than a bacterium, that can multiply only inside a living cell |
| communicable disease | a disease, caused by germs, that can spread to a person from another person, an animal, or an object |
| immune system | all the body parts and activities that fight disease |
| antibody | a chemical made by the immune system to fight a particular disease |
| immunity | the body's ability to protect itself or fight diseases caused by germs |
| vaccine | a medicine that causes the body to form antibodies against a certain disease |
| AIDS | a very serious disease in which the immune system is extremely weak |
| HIV | the virus that attacks the immune system and leads to AIDS |
| stress | the way the body and mind respond to changes around you |
