Which of the following organisms causes the most severe disease?
A) Treponema pallidum ID50 = [tex]$57$[/tex]
B) Rhinovirus 1D50-200
C) E. coli 0157 : [tex]$171050-20$[/tex]
D) Shigella ID50-10
E) Can't tell
Answer (1)
The problem asks to identify the organism causing the most severe disease based on ID50 values.
ID50 represents the number of organisms needed to infect 50% of a population; lower ID50 indicates higher severity.
Comparing the given ID50 values: Treponema pallidum (57), Rhinovirus (200), E. coli 0157 (20), and Shigella (10).
Shigella has the lowest ID50 (10), indicating it causes the most severe disease. D
Explanation
Understanding the Problem We are given the ID50 values for several organisms and asked to determine which causes the most severe disease. The ID50 (Infectious Dose 50) is the number of organisms required to infect 50% of a population. A lower ID50 indicates that fewer organisms are needed to cause infection, meaning the organism is more infectious and causes more severe disease.
Comparing ID50 Values We need to compare the ID50 values of the given organisms:
A) Treponema pallidum: ID50 = 57 B) Rhinovirus: ID50 = 200 C) E. coli 0157: ID50 = 20 D) Shigella: ID50 = 10
Identifying the Lowest ID50 Comparing the ID50 values, we have:
Treponema pallidum: 57 Rhinovirus: 200 E. coli 0157: 20 Shigella: 10
The lowest ID50 value is 10, which corresponds to Shigella.
Conclusion Therefore, Shigella causes the most severe disease because it has the lowest ID50 value, meaning it takes the fewest organisms to cause infection.
Final Answer The organism that causes the most severe disease is Shigella.
Examples
Understanding ID50 values is crucial in public health and epidemiology. For example, during a disease outbreak, knowing the ID50 of a pathogen helps in assessing the risk of infection and implementing appropriate control measures. If a pathogen has a low ID50, even a small number of organisms can cause widespread infection, necessitating stricter hygiene and quarantine protocols. Conversely, a higher ID50 might indicate that the pathogen requires a larger exposure for infection to occur, allowing for more targeted interventions.
