1. the improper functioning of the body brought about by heredity, infection, diet, or the environment protozoan infection 2. cannot be spread through contact or any mechanism of transmission infectious disease 3. caused by the spread of harmful microorganisms bacterial infection 4. caused by the multiplication of a small infectious agent which invades a host cell and then destroys it non-infectious disease 5. caused by the reproduction of a small infectious agent which produces poisons that destroy cells viral infection 6. caused by the multiplication of fungal organisms on or in the body fungal infection 7. caused by microscopic parasites disease