Answer :
An opportunistic pathogen may indeed be harmless in one host and pathogenic in another, as it typically causes disease in hosts who have impaired defenses. This is in contrast to primary pathogens, which can infect and cause disease in healthy hosts. Host-pathogen interactions are dynamic and depend on multiple factors.
The assertion that an opportunistic pathogen may be harmless in one host and pathogenic in another is true. An opportunistic pathogen is a type of microorganism that causes disease primarily in individuals whose host defenses are compromised. This compromising can be due to a variety of factors such as a weakened immune system, age, pregnancy, undergoing chemotherapy, having an immunodeficiency like AIDS, recovering from surgery, or suffering from breaches in protective barriers like severe wounds or burns.
Unlike primary pathogens that are capable of causing disease in a healthy host regardless of their immune status, opportunistic pathogens take advantage of the host's weakened defenses to establish infections. The interactions between a host and a pathogen are dynamic and include various factors like the pathogen's virulence, the number of microbes, the location of entry, and the host's overall health and defense state. Not all exposures to a pathogen will lead to disease, as a healthy host might be able to fight off the infection before symptoms develop.