What is an infectious agent?

What is an infectious agent?

• A. A host's immune response
• B. A non-pathogenic organism
• C. An environmental toxin
• D. A pathogen causing disease such as viruses, bacteria, protozoa, helminths, and fungi

Answer: (D)

An infectious agent is a biological entity capable of causing infection by invading and multiplying within a host. It includes viruses, bacteria, protozoa, helminths, and fungi, which are the organisms that can spread and lead to disease. This differs from a host’s immune response, which is the body's reaction to infection; a non-pathogenic organism, which may be present without causing disease; and environmental toxins, which cause damage through chemicals rather than infection.

An infectious agent is a biological entity capable of causing infection by invading and multiplying within a host. It includes viruses, bacteria, protozoa, helminths, and fungi, which are the organisms that can spread and lead to disease. This differs from a host’s immune response, which is the body's reaction to infection; a non-pathogenic organism, which may be present without causing disease; and environmental toxins, which cause damage through chemicals rather than infection.