How does enclosure design influence disease transmission in a mouse facility?

• A. Enclosure design has little effect on disease transmission.
• B. Carpeted floors in enclosures minimize spread.
• C. Proper ventilation, cleanable surfaces, and isolation of cages reduce aerosol spread and environmental contamination.
• D. Only the number of cages matters for disease control.

Answer: (C)

Enclosure design controls how infectious material moves through the facility by shaping airflow, filtration, and the cleanliness of contact surfaces. In a mouse facility, pathogens can travel in aerosols and persist on cage components and floors, so proper ventilation creates directional air flow and adequate air changes that dilute and remove aerosols, limiting their spread between cages. Using isolated or individually vented cages with HEPA filtration further reduces the chance that pathogens escape into shared spaces. Surfaces that are smooth, non-porous, and easy to disinfect minimize the risk of contamination transferring via hands, instruments, or cage parts. Isolating cages and maintaining clean workflows also cut cross-contamination when staff handle multiple cages or move between rooms. Carpeted floors and porous materials are harder to clean and can harbor microbes, so they don’t help reduce transmission. Having more cages matters for housing capacity, but without good ventilation, sanitation, and isolation, disease can still spread.