In an experiment to determine the infectious dose for a specific organism, 50% of the test subjects must develop the disease following a specific dose. This is quantified as the (ID₅₀) and is a measure of the pathogenicity of that organism. Assess the following data from an experiment involving 200 mice and determine the ID₅₀ for the infectious agent. Infectious Dose Living Mice Dead Mice
10³ 190 10
10⁴ 150 50
10⁵ 120 80
10⁶ 100 100
10⁷ 0 200

Question

Quizplus · Accepted Answer

In order to determine the infectious dose that results in 50% of the test subjects developing the disease, we need to find the dose that results in a 50:50 ratio of living and dead mice. Looking at the data, we can see that the first dose (10³) results in 10 dead mice out of 200, which is not a 50:50 ratio. The second dose (10⁴) results in 50% of the mice dying, but this is not the infectious dose because it is above the 50:50 ratio. The third dose (10⁵) results in 80 dead mice out of 200, which is also not a 50:50 ratio. However, the fourth dose (10⁶) results in 100 dead mice out of 200, which is a 50:50 ratio and therefore the infectious dose. The fifth dose (10⁷) results in all mice dying and therefore is not a valid dose to use for determining the infectious dose.

In an Experiment to Determine the Infectious Dose for a Specific