By: Annette Uda, Aerapy
Published: September 2024
In the realm of animal care and healthcare environments, the prevention of disease transmission is an ever-present challenge. Whether dealing with zoonotic diseases or protecting against the spread of common pathogens, understanding how diseases spread is essential for keeping both animals and humans safe. However, confusion still exists within the industry, particularly when it comes to how diseases are transmitted through the air.
One of the most misunderstood aspects of disease transmission is the distinction between droplet transmission and droplet nuclei transmission (aerosol transmission). This distinction is crucial for understanding how diseases travel and, ultimately, how we can prevent them. As Dr. Erica Tramuta-Drobnis, VMD, MPH, CPH from ELTD One Health Consulting, highlights, “Recognizing that airborne transmission encompasses more than just close proximity exposures and surface contamination with fomite risks (droplet transmission), it also includes particulates capable of traveling distances and lingering in the air for long periods of time (aerosol and droplet nuclei transmission), which is paramount to ensuring all avenues of protection are addressed and explored”¹.
Droplet Transmission vs. Droplet Nuclei Transmission
Droplet transmission occurs when infectious particles are expelled from a person or animal through actions such as sneezing, coughing, barking, or even panting. These droplets, typically larger than 5 to 10 microns, do not travel far, generally settling within a meter or two from the source. They pose a threat primarily through close contact, such as when people or animals are in close proximity for an extended time.
In contrast, droplet nuclei transmission—often referred to as aerosol transmission—deals with much smaller particles, typically less than 5 microns. These smaller particles can remain suspended in the air and viable for longer periods and travel greater distances, making them particularly dangerous in enclosed spaces like veterinary clinics, hospitals, boarding facilities, or grooming facilities. Unlike larger droplets that fall to the ground quickly, droplet nuclei can be carried by air currents and through HVAC systems, spreading pathogens throughout a facility without direct contact between infected individuals.
This is where much of the confusion arises. It is easy to assume that wearing masks and practicing hand hygiene are sufficient to prevent disease spread. While these methods are effective against larger droplet transmission, they do little to stop droplet nuclei from traveling through the air and infecting others. As research during the COVID-19 pandemic highlighted, aerosol transmission plays a significant role in spreading infectious diseases, even when surface disinfection and hand hygiene protocols are followed strictly.
Busting Myths About Airborne Transmission
One of the prevailing myths in the animal care industry is that diseases don’t linger long enough or travel far through the air. This misconception can create a false sense of security, leading staff to focus heavily on surface cleaning and hygiene while overlooking the critical airborne transmission routes. However, studies have shown that aerosolized pathogens can remain viable in the air for hours and can travel significant distances, especially in enclosed environments.
For example, respiratory pathogens like those responsible for Canine infectious respiratory disease complex (CIRD), canine influenza, or feline calicivirus can linger in the air long after an infected animal has left the room. This means that relying solely on traditional disinfection methods and close-contact precautions is insufficient for fully protecting animals and staff. In fact, focusing on droplet transmission alone neglects the significant risk posed by droplet nuclei that can spread through the air and infect those who haven’t had direct contact with the sick individual.
In a study by Jaynes et al., titled “Effect of Ultraviolet Germicidal Irradiation of the Air on the Incidence of Upper Respiratory Tract Infections in Kittens in a Nursery” ², the use of UV germicidal irradiation systems (GUV), including those manufactured by Aerapy, resulted in an 87.1% reduction in upper respiratory tract infections (URIs) among kittens when compared to years where UV systems were not used. The study emphasized that “airborne transmission of feline respiratory pathogens may be more important than has been previously recognized,” and that UV disinfection plays a crucial role in reducing these infections in animal care facilities.
The Role of Droplet Nuclei in Respiratory Infection Transmission
Research has shown that droplet nuclei (aerosols) are a primary transmission route for many respiratory infections, including those found in animal care environments. These smaller particles, typically less than 5 microns, can remain airborne for extended periods and travel longer distances compared to larger droplets. A comprehensive study by Tellier et al. (2019) emphasized that aerosol transmission plays a critical role in the spread of infectious agents such as influenza and other respiratory viruses³. The study highlights that recognizing and addressing this transmission route is crucial for effective infection control, particularly in indoor settings where ventilation may be limited. This underscores the need for air disinfection strategies, such as GUV, to mitigate the risks associated with droplet nuclei transmission.
The Vital Role of UV in Disease Mitigation
Given the risks posed by airborne transmission, it is clear that a more comprehensive infection control strategy is needed—one that includes disinfection not only of surfaces but also of the air itself. This is where Germicidal Ultraviolet (GUV) becomes indispensable. UV technology has been proven effective in inactivating airborne pathogens, offering a robust solution to mitigate the risks of droplet nuclei transmission.
Upper-air UV units, for example, work by continuously disinfecting the air in a room, ensuring that any airborne pathogens are neutralized before they have the chance to infect others. UV light effectively destroys the DNA or RNA of microorganisms, rendering them inactive and unable to spread infection. This approach is particularly valuable in high-risk environments like veterinary clinics, boarding facilities, and hospitals, where multiple animals may be in close quarters and airborne disease transmission is a real concern.
Furthermore, incorporating UV technology into HVAC systems ensures that any pathogens circulating through the air are exposed to UV light, significantly reducing their ability to spread through the building. UV technology doesn’t just trap pathogens, as air purifiers or HEPA filters might; it neutralizes them, offering a higher level of protection.
Closing the Gap in Infection Control
Infection control is not just about cleaning surfaces and washing hands. It’s about recognizing all the routes through which diseases can spread—particularly those that are less visible, like airborne transmission. By understanding the difference between droplet and droplet nuclei transmission, veterinary professionals and healthcare workers can take the necessary steps to protect their patients, staff, and facilities.
In closing, it is essential to recognize that UV technology is no longer a luxury but a necessity in comprehensive infection control plans. From reducing the spread of airborne diseases to improving overall air quality, UV disinfection offers a proven and effective solution for mitigating the risks posed by aerosolized pathogens. Incorporating this technology into animal care settings can help prevent outbreaks, protect animal and human health, and safeguard the future of care.
References:
- Tramuta-Drobnis, Erica. “Veterinary Infection Control Plans: Don’t Forget Aerosol Disease Transmission Prevention.” ELTD One Health Consulting. https://aerapyanimalhealth.com/veterinary-infection-control-plans-dont-forget-aerosol-disease-transmission-prevention
- Jaynes, Robyn A., Thompson, Melissa C., and Kennedy, Melissa A. *Effect of Ultraviolet Germicidal Irradiation of the Air on the Incidence of Upper Respiratory Tract Infections in Kittens in a Nursery*. Journal of the American Veterinary Medical Association, 2020, Vol 257: Issue 9. DOI: https://doi.org/10.2460/javma.257.9.929
- Tellier, R., et al. “Recognition of aerosol transmission of infectious agents: a commentary.” BMC Infectious Diseases, 2019. https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-019-3707-y
