What describes a pathogen that takes advantage of a host's compromised immune system?

An opportunistic pathogen is a type of microorganism that typically does not cause disease in a healthy host with a fully functioning immune system. However, when the host's immune defenses are weakened—due to factors such as underlying medical conditions, malnutrition, stress, or the effects of medications—these pathogens can take advantage of the situation and lead to infections. This characteristic makes them particularly notable in clinical settings, where individuals with compromised immunity, such as those undergoing chemotherapy or those with HIV/AIDS, are at increased risk for infections caused by opportunistic pathogens.

In contrast, invasive pathogens are known to cause disease in otherwise healthy individuals by actively invading tissues and evading the immune response, while secondary pathogens typically refer to infections that occur after the primary infection has weakened the immune system or caused tissue damage. Non-infectious pathogens describe agents that do not cause infection, such as toxins or prions, rather than microorganisms that invade and multiply within host tissues.