Controlling the transmission of airborne pathogens in a veterinary hospital presents a complex challenge. Respiratory droplets and aerosols emitted by infected patients when they exhale, cough, or vocalize circulate throughout various hospital areas from the lobby to discharge points, bypassing isolation strategies aimed at confining the patient to the examination room. This challenge has stimulated the quest for effective preventive measures to mitigate the spread of infection.
Airborne pathogens are expelled when patients breathe out, cough, or bark, producing a mixture of gasses, aerosols, and droplets known as a respiratory plume, which can quickly spread across the hospital. The management of these plumes is often hindered by the active movement of patients across different areas of the hospital. Hospitals generally regulate this issue by confining the patient to an examination room that is cleaned multiple times and left closed for 24 hours after the patient is discharged. Yet, this approach limits the availability of examination rooms and may inadvertently enhance the propagation of respiratory pathogens.
Aerosol transmission is a particularly tough barrier to control given the assortment of ways infectious diseases spread, including via vectors, direct contact, fomites, and fecal-oral routes. While a considerable volume of research literature addresses airborne transmission of pathogens in livestock and poultry, sparse concentration is specifically aimed at small animal pathogens control. To fill this gap, data from human research have been extrapolated and adapted to provide insight into the spread of respiratory pathogens, particularly in the light of ongoing COVID-19 research.
Many environmental factors influence the spread and deposition of disease-causing droplets and aerosols. The size of these droplets greatly determines their behavior- larger droplets fall to a surface within minutes, while smaller aerosols can remain suspended in the air for several hours. Temperature, relative humidity, air movement, and air filtration also significantly impact pathogen transmission.
For instance, a warmer respiratory aerosol plume can rise and spread throughout the hospital in prevailing air currents if the plume’s temperature is higher than that of the room. Studies have demonstrated that lower relative humidity speeds up the dehydration of droplets, allowing smaller aerosols to remain suspended in the air, thus heightening the transmission risk. It also affects the survival of viruses versus bacteria differently, making it tricky to establish an ideal relative humidity level for prevention.
The introduction of air purifiers into the examination room could offer a solution. Research has shown that local air purifiers can remove over 50% of airborne virions, significantly reducing airborne pathogen counts. Ideal air purifiers should possess a high-efficiency particulate air (HEPA) filter and prefilters, which trap larger particles and extend the HEPA filter’s lifespan.
In combination with air purifiers, the routine cleaning of surfaces as per the disinfectant manufacturer’s recommendations should be maintained, as larger droplets deposit pathogens on surfaces before dehydrating. The timely replacement of HEPA filters and weekly assessment of pre-filters are critical maintenance practices to optimize the usefulness of an air purifier.
The employment of an air purifier may also effectively reduce the closure of examination rooms for cleaning post-patient-discharge from 24 hours to just 30 minutes. Adopting these measures in recent past has led to a significant drop in the transmission rates of recent respiratory outbreaks in certain hospitals.
Source: https://www.dvm360.com/view/clearing-the-air-in-contaminated-spaces