list the types of infectious agents that may infect the human body
A. fungi, hookworms sore throats bugs
B. immune system diseases viruses fungi
C. infection sickness bacteria attackers
D. viruses bacteria, fungi, and parasites
These agents are commonly grouped as viruses, rickettsia, bacteria, fungi, and parasites. The disease that these organisms cause is only incidental to their struggle for survival.
Most of these agents do not require a human host for their life cycles. Many survive readily in soil, water, or lower animal species and are harmless to humans.
