Highly virulent organisms need to be present in large numbers in order to cause infection. Select one: a. TRUE b. FALSE

Answer

The correct answer is FALSE. Virulence refers to the degree of pathogenicity or the severity of the disease that a microorganism can cause. Highly virulent organisms are extremely effective at overcoming host defenses and causing disease even when present in very small quantities. In microbiology, this is often expressed as a low ID50 (the infectious dose required to cause infection in 50% of a test population). Conversely, organisms with low virulence typically require a much larger number of cells or viral particles (a high infectious dose) to successfully establish an infection.