Which statement best describes the relationship between minimal infectious dose and transmission?

• A. Higher minimal infectious dose increases transmission likelihood.
• B. Lower minimal infectious dose increases transmission likelihood.
• C. Minimal infectious dose has no effect on transmission.
• D. Minimal infectious dose affects only the incubation period.

Answer: (B)

Minimal infectious dose is the smallest amount of pathogen needed to establish infection in a susceptible host. If this quantity is low, even small or brief exposures can cause infection, which means more opportunities for the pathogen to spread to others. In contrast, a high minimal infectious dose requires a larger exposure to cause infection, making transmission less likely during typical contact. While dose can influence the incubation period, the essential idea of the minimal infectious dose is about whether infection occurs at all after exposure, which directly shapes how readily a pathogen can be transmitted. Therefore, a lower minimal infectious dose increases transmission likelihood.