Which factor is a main consideration when determining the number of sentinel animals?

Which factor is a main consideration when determining the number of sentinel animals?

• A. The space available in the animal room
• B. The cost involved in maintaining the animals
• C. The number of pathogens being tested
• D. The expected morbidity of the agents being monitored

Answer: (D)

The main idea here is how to size a sentinel program based on how likely it is that an infection would be detected in sentinels. You want enough sentinel animals to have a good chance of catching an infection if it’s present in the colony. That likelihood is largely driven by how the agents being monitored affect the sentinels—i.e., their morbidity. If an agent has high morbidity and infections in sentinels show clear illness or seroconversion, fewer sentinels can still give you reliable detection. If morbidity is low and infections in sentinels are mild or subclinical, you’d need more sentinels to achieve the same level of detection confidence. Space and cost are practical constraints, and the number of pathogens being tested affects the scope of surveillance, but the choice that most directly influences how many sentinels you need is the expected morbidity of the agents being monitored.

The main idea here is how to size a sentinel program based on how likely it is that an infection would be detected in sentinels. You want enough sentinel animals to have a good chance of catching an infection if it’s present in the colony.

That likelihood is largely driven by how the agents being monitored affect the sentinels—i.e., their morbidity. If an agent has high morbidity and infections in sentinels show clear illness or seroconversion, fewer sentinels can still give you reliable detection. If morbidity is low and infections in sentinels are mild or subclinical, you’d need more sentinels to achieve the same level of detection confidence.

Space and cost are practical constraints, and the number of pathogens being tested affects the scope of surveillance, but the choice that most directly influences how many sentinels you need is the expected morbidity of the agents being monitored.