Bacteria, fungi, viruses or protoctists that get into the body and cause damage.

An illness, when the body is not working properly.

A disease caused by the body’s immune system attacking its own body cells and damaging them.

A disease caused by a pathogen getting into the body and damaging it.

A microbe that has no cell structures. The outer protein coat surrounds its genetic material.

An illness that is inherited from parents, such as sickle-cell disease.

Keeping things clean, and clear of infectious microbes.

A disease that damages the nervous system and can cause paralysis of muscles, making it difficult to move.

A disease caused by the lack of a nutrient in the diet, such as kwashiorkor.