Why is it recommended that sentinel cages be moved frequently around the room?

• A. To ensure that the sentinels are unaffected by variations in air flow or humidity
• B. To allow airborne transmission to be sampled from different areas of the room
• C. To avoid spreading disease by long-term exposure to sick animals
• D. To ensure that the sentinels are in contact with all animals in the room

Answer: (B)

The main idea is to detect airborne transmission across the room rather than just in one spot. In an animal housing room, air flow isn’t perfectly uniform—there are patterns created by HVAC supply and exhaust, cage layout, and local activities. If sentinel cages stay in one location, they might miss a localized plume of aerosols or areas with higher exposure, giving a false sense that no airborne pathogens are present. By moving sentinel cages to different areas, you sample across the room, increasing the chance of catching any airborne transmission if it’s occurring in any part of the space. This approach provides a more representative picture of room-wide exposure.

It’s not about making sentinels unaffected by air flow or humidity, nor about spreading disease or guaranteeing contact with every animal. The goal is representative airborne surveillance, using relocation to account for how air moves through the room.