Which of the following organisms would be considered the most virulent, based on their infectious dose (ID50) ?

A. Vibrio cholerae, ID50 = 1,000,000,000B. Mycoplasma tuberculosis, ID50 = 10C. Rickettsia rickettsii, ID50 = 1

Answer: Rickettsia rickettsii ID50 = 1

Explanation:

Virulence is the pathogen's ability to cause infection or harm to the host. ID50 is the Infection Dose or the number of organisms required to cause infection on 50% of normal adult humans. A lower ID50 means that the pathogen has a higher virulence.

In this particular case, Rickettsia rickettsii would be the most virulent organism