Which factor refers to characteristics that make a host more susceptible to infection?

Host factors refer to the inherent characteristics of an individual that can increase their susceptibility to infections. These characteristics can include age, gender, underlying health conditions, immune status, and genetic predispositions. For example, young children and elderly individuals often have weakened immune systems, making them more vulnerable to infections. Similarly, individuals with chronic diseases such as diabetes or those undergoing immunosuppressive treatments are also at a higher risk of infection due to their compromised immune responses. Understanding host factors is crucial for infection control practices, as it helps in identifying individuals who may need extra protection or targeted interventions to prevent infections.

Environmental factors, while they play a significant role in infection transmission, are not intrinsic characteristics of the host. Pathogen strength refers to the virulence and pathogenicity of the microorganism, which does not specifically relate to the host's susceptibility. Transmission modes describe how an infection spreads from one person to another, which is unrelated to the host's individual characteristics.