Spread Of Airborne Infections Research Articles

A fieldable process for sensitive detection of airborne viruses via electrophoresis-based RNA enrichment

Sensitive on-site virus detection is a requirement for timely action against the spread of airborne infection since ultra-low in-air viral concentrations can readily infect individuals when inhaled. Here, we consider a fieldable biosensing process that incorporates a fast RNA enrichment step in order to concentrate viral RNA in a small volume prior to RT-qPCR. The enrichment approach uses electrophoresis in an RT-qPCR-compatible buffer, and allows for concentration of RNA by nearly 5-fold within only 10 min. In order to place this performance into context, we analyzed the minimum detectable concentration of a low-cost, fieldable, biosensing process that uses electrostatic precipitation for air sampling, heating for viral RNA extraction, and then RNA enrichment, followed by RT-qPCR. With enrichment, we estimated an in-air concentration of 5,654 genome copies (gc)/m3 with a 100% detection rate and an in-air concentration of 4,221 gc/m3 with a 78.6% detection rate. Given that the concentrations of common viruses, such as influenza and SARS-CoV-2, in several indoor spaces are between 5,800 and 37,000 gc/m3, we conclude that enrichment allows a detection that is sufficiently sensitive for practical applications.

Contact tracing & super-spreaders in the branching-process model

In recent years, it became clear that super-spreader events play an important role, particularly in the spread of airborne infections. We investigate a novel model for super-spreader events, not based on a heterogeneous contact graph but on a random contact rate: Many individuals become infected synchronously in single contact events. We use the branching-process approach for contact tracing to analyze the impact of super-spreader events on the effect of contact tracing. Here we neglect a tracing delay. Roughly speaking, we find that contact tracing is more efficient in the presence of super-spreaders if the fraction of symptomatics is small, the tracing probability is high, or the latency period is distinctively larger than the incubation period. In other cases, the effect of contact tracing can be decreased by super-spreaders. Numerical analysis with parameters suited for SARS-CoV-2 indicates that super-spreaders do not decrease the effect of contact tracing crucially in case of that infection.

Air Quality in Dental Care Facilities: Update to Current Management and Control Strategies Implementing New Technologies: A Comprehensive Review.

The quality of indoor air in healthcare facilities, with an emphasis on dental offices, attracted the attention of the scientific community in the late 1960s. Since then, it has become evident that the indoor air quality is critical in modern dental care facilities for limiting the spread of airborne infections, including vaccine-preventable diseases, and a key component of safety for healthcare personnel and patients. In the past decades, the role of indoor air quality has also been recognized in non-healthcare facilities, given the increasing time spent indoors by humans. During the provision of dental care services, mainly in the field of restorative dentistry, high-speed dental handpieces emitting air and water are used, producing large quantities of aerosol and hovering inside the operations area. In modern dental offices, new devices emitting air/powder for cavities improvement and cleaning as well as for periodontal prophylactic cleaning and aesthetics are used. In addition, a new therapeutic protocol for the removal of bacterial biofilm, targeting treatment for peri-implant diseases and conditions using air-abrasive decontamination technology, has been introduced in daily dental practice. The aim of this non-systemic review is to present the current state of knowledge on the nature and dynamics of air splatters and to provide an update to management and control strategies in dental care facilities, focusing on air purification and ultraviolet devices proposed and used. The findings arising from the limited number of related published articles documenting the reduction in levels of particular matter 2.5 (PM2.5), PM10 and volatile organic compounds, allow us to conclude that the continuous operation of air purifiers during and after treatment, contributes considerably to the improvement of the indoor air quality in dental care facilities. Moreover, the utilization of air purifiers is highly recommended in dental practice to mitigate spread of infections, including vaccine-preventable diseases. Frequent cleaning and maintenance of the purifier sieves and filters and frequent renovation of the indoor air through physical ventilation by mean of open windows is imperative. More research on environmental contamination and particularly on viral contamination under real dental care conditions is needed.

USING AIR EXCHANGE TO REDUCE THE PROBABILITY OF SPREADING CORONAVIRUS INFECTION

Statement of the problem. Ventilation processes have a significant impact on the spread of airborne infections. It is necessary to use air exchange to reduce the likelihood of spreading such infections. Mathematical model. Using the Wells - Riley model of airborne transmission of infectious diseases, a mathematical model has been developed for the spread of coronavirus infection in a medical institution, consisting of a group of communicating rooms in which both healthy and infected people are constantly located and moved. The mathematical model makes it possible to take into account the movement of people around the premises and the settling of quanta of the generation of infection by a sick person when air moves. Results. The general solution of the mathematical model is obtained, which allows calculating the concentration of quanta of generation of infection in the premises during the operation of a medical institution.Conclusions. The developed mathematical model of a medical institution allows a deeper understanding of the possibilities of the spread of coronavirus infection and taking these risks into account when designing medical institutions.

Air Flow Door Barrier for Airborne Infection Isolation Rooms

Airborne Infection Isolation Rooms (AIIRs) are used in hospitals to counter the spread of airborne infections. These rooms usually work well as long as the doors to the patient rooms are closed. However, passage through open doorways initiates air flows that may lead to containment failure. This paper presents a new “Air Flow Door Barrier” system for AIIRs and analyses its efficiency through CFD simulations. The overset mesh method is used to represent a hinged door and a person transiting from the patient room to the anteroom. The new system consists of a fan which introduces filtered patient room air into the anteroom through large displacement diffusors. It runs in synchronization with the door operator and produces an evenly distributed velocity across the open doorway. It is found that the system has the potential to remove nearly all transfer of air out from the patient room. The development of the system is part of an ongoing project aimed at finding cost-effective solutions for retrofitting existing patient rooms. However, the system also has the potential to be beneficial when considering inclusion in new standard AIIRs.

Analysing the link between public transport use and airborne transmission: mobility and contagion in the London underground

BackgroundThe transmission of infectious diseases is dependent on the amount and nature of contacts between infectious and healthy individuals. Confined and crowded environments that people visit in their day-to-day life (such as town squares, business districts, transport hubs, etc) can act as hot-spots for spreading disease. In this study we explore the link between the use of public transport and the spread of airborne infections in urban environments.MethodsWe study a large number of journeys on the London Underground, which is known to be particularly crowded at certain times. We use publically available Oyster card data (the electronic ticket used for public transport in Greater London), to infer passengers’ routes on the underground network. In order to estimate the spread of a generic airborne disease in each station, we use and extend an analytical microscopic model that was initially designed to study people moving in a corridor.ResultsComparing our results with influenza-like illnesses (ILI) data collected by Public Health England (PHE) in London boroughs, shows a correlation between the use of public transport and the spread of ILI. Specifically, we show that passengers departing from boroughs with higher ILI rates have higher number of contacts when travelling on the underground. Moreover, by comparing our results with other demographic key factors, we are able to discuss the role that the Underground plays in the spread of airborne infections in the English capital.ConclusionsOur study suggests a link between public transport use and infectious diseases transmission and encourages further research into that area. Results could be used to inform the development of non-pharmacological interventions that can act on preventing instead of curing infections and are, potentially, more cost-effective.

Role of high-efficiency particulate arrestor filters in control of air borne infections in dental clinics

Infections in dental practice may be transmitted by several routes, including direct contact with blood, oral fluids, or other secretions, through indirect contact with contaminated instruments and surgical equipments, through contact with aerobiological contaminants present in either droplet spatter or the aerosols resulting from oral and respiratory fluids. Preventing the spread of air borne infection is gaining importance in dental set ups because a large number of bacteria and viruses are transmitted through this route and prove to be a health hazard for both patients and dental health care personnel. High-efficiency particulate arresting (HEPA) air filters are very effective in reducing bioaerosols, and hence, preventing air borne infection. This paper discusses the role of HEPA filters in controlling air borne infections in dental clinics.

Intercomparison of Instruments Used for Safety and Performance Measurements of Ultraviolet Germicidal Irradiation Lamps

Public health concerns such as multidrug-resistant tuberculosis, bioterrorism, pandemic influenza, and sick building syndrome have brought about increased interest in the use of ultraviolet germicidal irradiation (UVGI) to prevent the spread of airborne infection. UVGI lamps require that radiometric measurements be performed to ensure their safe and effective use. This study evaluates 10 detectors that measure the ultraviolet radiation hazard of low-pressure mercury UVGI lamps, including a polychromator spectroradiometer, narrowband detectors designed to measure the ultraviolet radiation in a short range of wavelengths, and broadband detectors with a varying spectral response designed to follow the UV hazard action spectrum. The angular responses, spectral responses, and linearity of the detectors were measured and compared. The agreement between the measured angular responses and the ideal cosine responses varied widely among the detectors, and in general, the detectors with diffusing optics agreed significantly better with the ideal cosine response. The spectral responses at 254 nm also varied widely among the detectors, and, in general, the narrowband detectors agreed more closely with the 254 nm irradiances measured under the same conditions by a double monochromator spectroradiometer. All detectors displayed good linearity. The angular and spectral response data were then used to develop correction factors for the effective irradiance measurements of two UVGI sources, each measured at 10, 20, and 30 cm. The measured effective irradiances were compared with those measured by a double monochromator spectroradiometer with an integrating sphere input optic. Prior to correction, the effective irradiances measured by the detectors varied widely, ranging from 0.29 to 2.7 times those measured by the spectroradiometer. The application of cosine and spectral response correction factors significantly improved the agreement for the effective irradiances measured by all of the detectors, typically to within 10–20%. Awareness of these detector characteristics can play a key role in ensuring the accuracy of health hazard measurements of UVGI lamps.

VENTILATION IN THE SPREAD OF CHICKENPOX AND MEASLES WITHIN SCHOOL ROOMS

School ventilation, which has necessarily been curtailed on account of fuel shortages during the war, will probably never return to prewar standards. Enlightened opinion, which formerly opposed, on hygienic grounds, lowering the volume of air change, now recognizes the potentiality of higher standards of sanitary ventilation through air disinfection, which can practicably provide the hygienic equivalent of ventilation impossible of attainment by actual air replacement. Studies, begun in the autumn of 1937, were undertaken to test the hypothesis that the spread of air-borne infection in school rooms could be controlled by radiant disinfection of air. If micro-organisms are air borne, it follows that in a group of persons sharing a confined atmosphere for a given period of time the chance that an infective organism floating in the air will be breathed by a person susceptible to that particular disease is proportionate to the concentration of susceptibles in the atmosphere, just