Final answer:
Factors that make a person more susceptible to developing an infection include preexisting conditions and environmental factors, genetic immune factors, and weakened immune systems due to age or unrelated illnesses.
Step-by-step explanation:
There are several factors that make a person more susceptible for developing an infection from disease. First, preexisting conditions and environmental factors, such as exposure to secondhand smoke, can create conditions favorable for microbial growth or compromise the immune system. Second, individuals may have genetically determined immune factors that protect them from certain strains of pathogens. Lastly, some people have weaker immune systems due to age or unrelated illnesses, making them more vulnerable to infections.