Recognition of aerosol transmission of infectious agents: a commentary
Raymond Tellier1, Yuguo Li2, Benjamin J Cowling3
1Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, AB, Canada.
Abstract:
Although short-range large-droplet transmission is possible for most respiratory infectious agents, deciding on whether the same agent is also airborne has a potentially huge impact on the types (and costs) of infection control interventions that are required.The concept and definition of aerosols is also discussed, as is the concept of large droplet transmission, and airborne transmission which is meant by most authors to be synonymous with aerosol transmission, although some use the term to mean either large droplet or aerosol transmission.However, these terms are often used confusingly when discussing specific infection control interventions for individual pathogens that are accepted to be mostly transmitted by the airborne (aerosol) route (e.g. tuberculosis, measles and chickenpox). It is therefore important to clarify such terminology, where a particular intervention, like the type of personal protective equipment (PPE) to be used, is deemed adequate to intervene for this potential mode of transmission, i.e. at an N95 rather than surgical mask level requirement.With this in mind, this review considers the commonly used term of 'aerosol transmission' in the context of some infectious agents that are well-recognized to be transmissible via the airborne route. It also discusses other agents, like influenza virus, where the potential for airborne transmission is much more dependent on various host, viral and environmental factors, and where its potential for aerosol transmission may be underestimated.
Insights
Understanding airborne transmission is crucial for effective infection control. This review clarifies terminology around aerosol and droplet transmission for respiratory pathogens, impacting personal protective equipment (PPE) choices.
Area of Science:
- Infectious Diseases
- Epidemiology
- Public Health
Background:
- Distinguishing between droplet and airborne transmission of respiratory pathogens is critical for selecting appropriate infection control measures.
- Terminology surrounding aerosol and droplet transmission is often used inconsistently, leading to confusion in clinical practice.
- The type of personal protective equipment (PPE) required, such as N95 respirators versus surgical masks, depends heavily on the mode of transmission.
Purpose of the Study:
- To clarify the terminology of airborne, aerosol, and droplet transmission for respiratory infectious agents.
- To review the evidence for airborne transmission of well-established airborne pathogens (e.g., tuberculosis, measles, chickenpox).
- To discuss pathogens like influenza where airborne transmission potential may be underestimated and influenced by multiple factors.
Main Methods:
- Literature review and conceptual analysis of transmission routes for respiratory infectious agents.
- Examination of existing definitions and common usage of terms like 'aerosol transmission' and 'airborne transmission'.
- Case examples of pathogens with clear airborne routes and those with variable transmission dynamics.
Main Results:
- Inconsistent use of terms like 'aerosol' and 'airborne' transmission complicates infection control strategies.
- Pathogens like tuberculosis, measles, and chickenpox are well-recognized as primarily airborne.
- For agents like influenza, airborne transmission potential is highly variable, depending on host, viral, and environmental factors, and may be underestimated.
Conclusions:
- Clearer definitions and consistent terminology are essential for accurate risk assessment and effective infection control interventions.
- The distinction between transmission routes directly influences the selection of appropriate PPE, impacting cost and efficacy.
- Further research is needed to fully understand the variable airborne transmission potential of certain pathogens, like influenza, to optimize public health strategies.
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