What is the multiplication of disease-causing microorganisms in the body known as?

The term referring to the multiplication of disease-causing microorganisms in the body is infection. Infection occurs when pathogens, such as bacteria, viruses, fungi, or parasites, invade and begin to multiply within a host. This can lead to various symptoms and health issues, depending on the type of microorganism and the body's immune response.

Immunosuppression refers to a reduction in the immune system's ability to fight off infections, making the body more susceptible to diseases, but it does not itself describe the process of microorganisms multiplying. Incompatibility generally pertains to a lack of compatibility between agents, such as blood types or organ transplants, and does not relate to the multiplication of microorganisms. Inflammation is the body's response to injury or infection, characterized by redness, heat, swelling, and pain, but it is a reaction to the presence of infection rather than the actual multiplication of microorganisms themselves. Therefore, infection is the most accurate term to describe this phenomenon.