A susceptible host is described as each of the following except:

• A. An individual who has been vaccinated against the pathogen
• B. A person with chronic underlying health conditions
• C. An individual with a weakened immune system
• D. A person lacking immunity to a specific pathogen

Answer: (A)

Verified step by step guidance

1. Understand the definition of a susceptible host in microbiology: it refers to an individual who is vulnerable to infection by a pathogen because they lack effective immunity or defenses.
2. Analyze each option to determine if it fits the definition of a susceptible host:
3. Option 1: 'An individual who has been vaccinated against the pathogen' - vaccination typically provides immunity, so this person is generally not susceptible.
4. Option 2: 'A person with chronic underlying health conditions' - such conditions can weaken defenses, making the person more susceptible.
5. Option 3: 'An individual with a weakened immune system' - a weakened immune system reduces the ability to fight infections, increasing susceptibility.
6. Option 4: 'A person lacking immunity to a specific pathogen' - lacking immunity directly means susceptibility to that pathogen.