If a pathogen has an ID50 of 500 organisms, how many organisms are needed to inf

Practice Questions

Q1
If a pathogen has an ID50 of 500 organisms, how many organisms are needed to infect 50% of a population of 1,000 individuals?
  1. 250
  2. 500
  3. 1,000
  4. 1,500

Questions & Step-by-Step Solutions

If a pathogen has an ID50 of 500 organisms, how many organisms are needed to infect 50% of a population of 1,000 individuals?
  • Step 1: Understand what ID50 means. ID50 is the number of organisms needed to infect 50% of a population.
  • Step 2: Note that the ID50 for the pathogen is given as 500 organisms.
  • Step 3: Recognize that the population size is 1,000 individuals.
  • Step 4: Since ID50 is defined as the amount needed to infect 50% of the population, we need to find 50% of 1,000 individuals.
  • Step 5: Calculate 50% of 1,000, which is 500 individuals.
  • Step 6: Since the ID50 is 500 organisms, this means that to infect 50% of the 1,000 individuals, you need 500 organisms.
  • Infectious Dose (ID50) – ID50 refers to the number of organisms required to infect 50% of a given population.
  • Population Size – Understanding that the ID50 is independent of the total population size when calculating the dose needed to infect 50%.
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