Airborne transmission of respiratory viruses

SARS-CoV-2 epidemiology, kinetics, and evolution: A narrative review

Since winter 2019, SARS-CoV-2 has emerged, spread, and evolved all around the globe. We explore 4 y of evolutionary epidemiology of this virus, ranging from the applied public health challenges to the more conceptual evolutionary biology perspectives. Through this review, we first present the spread and lethality of the infections it causes, starting from its emergence in Wuhan (China) from the initial epidemics all around the world, compare the virus to other betacoronaviruses, focus on its airborne transmission, compare containment strategies ("zero-COVID" vs. "herd immunity"), explain its phylogeographical tracking, underline the importance of natural selection on the epidemics, mention its within-host population dynamics. Finally, we discuss how the pandemic has transformed (or should transform) the surveillance and prevention of viral respiratory infections and identify perspectives for the research on epidemiology of COVID-19.

An AIE-active Janus filter membrane for highly efficient detection and elimination of bioaerosols

Highly efficient detection and sterilization techniques for bioaerosol prevention and control are urgently needed. Herein, we present an AIE-active Janus air filter membrane (AIE-HAFM) that features water-dissolvable micro-nano porous network architecture and aggregation-induced emission (AIE) activity constructed by the asymmetrical surface modification with an amphiphilic AIE photosensitizer (MeOTTVP). The all-round AIE-HAFM can not only provide low pressure drop and high interception efficiency for bioaerosol sampling but also perfectly inherit the AIE functions of MeOTTVP, which allows for intensive near-infrared (NIR) emission and efficient production of reactive oxygen species. The airborne pathogens can be effectively captured, collected, transferred, and released by AIE-HAFM for subsequent quantitative detection with colony counting and ATP bioluminescence, as well as stained by the incorporated MeOTTVP for NIR fluorescence imaging-guided visual detection. Meanwhile, AIE-HAFM enables on-demand and surface-dependent photodynamic effects for reliable bacterial eradication under white light irradiation due to the surface-concentrated MeOTTVP, consequently achieving the smart prevention and control of bioaerosols both in the simulated and real-world bioaerosol environment. The versatility of AIE-HAFM in handling diverse airborne pathogens may bring about a transformative solution to address the bioaerosol contamination problems.

Underrated risk of antibiotic resistance genes dissemination mediated by bioaerosols released from anaerobic biological wastewater treatment system

Antibiotic resistance has been recognized as one of the most prevalent public health problems. The bioaerosol-mediated spread of antibiotic resistance genes (ARGs) is an important but underrated pathway. Therefore, this work investigated the comprehensive resistome and pathogen-induced risk in bioaerosols released from anaerobic ammonium oxidation (anammox) process under antibiotic stress. The results showed that the bioaerosol oxidation potential increased by 2.7 times after the addition of sulfamethoxazole (SMX) into the anammox system. Based on the metagenomic analyses, abundant ARGs were enriched in bioaerosols, especially novA, olec, msbA and patA. There were many antibiotic resistance contigs carrying at least two mobile genetic elements (MGEs) in bioaerosols. Compared to the control, SMX caused the significant increase in ARGs proportion in plasmids from 11.4 % to 19.4 %. Similarly, the abundance of the type IV secretion system protein encoding genes (mtrA and mtrB) increased by 30.2 % and 31.5 %, respectively, which was conducive to gene transfer between bacteria. In addition, SMX stress induced the reactive oxygen species (ROS) production and the upregulation of genes related to membrane protein and DNA replication, further facilitating ARGs transfer. The co-occurrence networks showed that Aquamicrobium and Microbacterium probably were the hosts of most ARGs. Notably, four abundant human pathogens were detected in bioaerosols from the anammox system, which raised concerns on the health risk of resistant bioaerosol diffusion. These findings reveal the potential of horizontal gene transfer through bioaerosols and provide a guidance for systematically assessing the risk of environmental antibiotic resistance and relevant pathogens.

Global impact of hMPV virus: Transmission, pathogenesis, diagnostic and treatment

The Human Metapneumovirus (hMPV), a member of the Pneumovirinae subfamily, is a substantial cause of acute lower respiratory infections, notably in young children, the elderly, and immunocompromised patients. It was first identified in 2001, hMPV has displayed a seasonal pattern of infection, with symptoms ranging from moderate to severe respiratory disease. This study investigates the worldwide effect of hMPV, concentrating on its transmission, etiology, diagnostics, and treatment techniques, underlining the need for better public health measures. hMPV is spread by respiratory droplets, with a normal incubation period of 3-5 days. The virus induces an immune response characterized by pro-inflammatory cytokines, leading to respiratory symptoms and probable tissue damage. Diagnostic breakthroughs, including RT-qPCR and mNGS, have enhanced detection sensitivity. However, therapy is generally supportive, with potential breakthroughs in mRNA vaccines targeting hMPV fusion proteins. Current clinical studies evaluate the effectiveness and safety of these new vaccinations, which might pave the road for effective prevention. Despite tremendous gains in understanding hMPV, there remains a crucial need for targeted antiviral treatments and vaccines to minimize its worldwide health impact.

Assessing airborne pathogen exposure in hospital wards using a distance-based modeling technique

Positioning nursing staff in hospital wards to patients is crucial for estimating infection risk, as the time distribution across interpersonal distances between nursing staff and patients significantly determines the inhalation fraction and, thus, the infection risk. Therefore, the study proposed a distance-based inhalation model for assessing spatial exposure to airborne pathogens in in-ward cubicles, where the movement data collected in a simulated ward was utilized to estimate the airborne pathogen exposure in this specific movement profile. Further demonstrations explored the impact of different bed arrangements in hospital wards and the distributions of exposure fractions through short-range inhalation on spatial exposure. The results indicated that different bed arrangements substantially impacted the probability of nurse stay and the associated exposure during a work shift. These findings offer valuable insights for targeted strategies to minimize close contact, improve ward management, and enhance infection control practices in healthcare facilities, contributing to improved occupant safety and well-being.

Destruction of virus particles via mechanical and chemical virucidal activity of nanocolumnar copper thin films

Human-generated droplets, which facilitate the transmission of viral infections, include large droplets and aerosols. The drying rates of these droplets upon adhesion to a surface vary significantly owing to the wide range of their sizes (∼nine orders of magnitude). Consequently, combating viruses requires distinct strategies under wet and dry conditions. However, studies that account for these two contrasting conditions are lacking. In the present study, we replicated these conditions and investigated the topographical properties of enveloped bacteriophages as an indicator of viral integrity via high-speed atomic force microscopy. Under wet conditions, a reduction in the virus particle volume was observed only on a nanocolumnar copper (NC-Cu) thin film and not on a chemically stable nanocolumnar cupric oxide (NC-CuO) thin film. In contrast, under dry conditions, virus particles lost their shape integrity on both NC-CuO and NC-Cu films. The deformation of virus particles on the NC-CuO film under dry conditions suggests a mechanism distinct from the chemical activity of Cu (i.e., mechanical activity). These results indicate that dry conditions trigger the mechanical activity of nanostructured surfaces. This highlights the significance of nanostructure-induced mechanical activity in virus inactivation under dry conditions, such as those involving viruses in small droplets or aerosols.

Capsid and genome damage are the leading inactivation mechanisms of aerosolized porcine respiratory coronavirus at different relative humidities

Relative humidity (RH) varies widely in indoor environments based on temperature, outdoor humidity, heating systems, and other environmental conditions. This study explored how RH affects aerosolized porcine respiratory coronavirus (PRCV), a model for coronaviruses, over a time range from 0 min to a maximum of 1 h, and the molecular mechanism behind viral infectivity reduction. These questions were answered by quantifying: (i) viral-host receptor interactions, (ii) capsid integrity, (iii) viral genome integrity, and (iv) virus infectivity. We found RH did not alter PRCV-receptor interactions. RHs 45-55% and 65-75% damaged viral genomes (2 log10 reduction and 1 log10 reduction, respectively, in terms of median sample value), whereas RHs 55-65% decreased capsid integrity (2 log10 reduction). No apparent virion damage was observed in RH 75-85%. Two assays were used to quantify virus presence: qPCR for detecting the viral genomes and plaque-forming unit assay for detecting the virus replication. Our results indicated that the qPCR assay overestimated the concentrations of infectious viruses, and RNase treatment with long-range RT-qPCR performed better than one-step RT-qPCR. We propose that understanding the influence of RH on the stability of aerosolized viruses provides critical information for detecting and preventing the indoor transmission of coronaviruses.

IMPORTANCE

Indoor environments can impact the stability of respiratory viruses, which can then affect the transmission rates. The mechanisms of how relative humidity (RH) affects virus infectivity still remain unclear. This study found RH inactivates porcine respiratory coronavirus by damaging its capsid and genome. The finding highlights the potential role of controlling indoor RH levels as a strategy to reduce the risk of coronavirus transmission.

Electromagnetic waves destabilize the SARS-CoV-2 Spike protein and reduce SARS-CoV-2 Virus-Like particle (SC2-VLP) infectivity

Infection and transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to pose a global public health concern. Using electromagnetic waves represents an alternative strategy to inactivate pathogenic viruses such as SARS-CoV-2. However, whether electromagnetic waves reduce SARS-CoV-2 infectivity is unclear. Here, we adapted a coplanar waveguide (CPW) to identify frequencies that could potentially neutralize SARS-CoV-2 virus-like particles (SC2-VLPs). Treatment of SC2-VLPs at frequencies between 2.5 and 3.5 GHz and an electric field of 413 V/m reduced infectivity. Exposure of SC2-VLPs to a frequency of 3.1 GHz -and to a lesser extent, 5.9 GHz- reduced their binding to antibodies targeting the SARS-CoV-2 Spike S1 receptor-binding domain (RBD) but did not alter the total levels of Spike, Nucleocapsid, Envelope, or Membrane proteins in virus particles. These results suggest that electromagnetic waves alter the conformation of Spike, thereby reducing viral attachment and entry. Overall, this data provides proof-of-concept in using electromagnetic waves for sanitation and prevention efforts to curb the transmission of SARS-CoV-2 and potentially other pathogenic enveloped viruses.

Preventing respiratory viral transmission in healthcare settings

PURPOSE OF REVIEW

The COVID-19 pandemic catalyzed new insights into respiratory viral transmission mechanisms and prevention. We review the most practical and impactful measures to prevent SARS-CoV-2 and other nosocomial respiratory viral infections in healthcare.

RECENT FINDINGS

Nosocomial respiratory viral infection rates mirror viral activity levels in the surrounding community. During peak periods ∼15-20% of hospitalized patients with respiratory viral infections may have acquired their virus in the hospital. Nosocomial respiratory viral infections are associated with increased lengths-of-stay, risk of respiratory failure, and hospital death. Most procedures contribute minimally to aerosol production compared to labored breathing, coughing, and forced expiration. Masking for source control and exposure control both decrease transmission risk, respirators more so than masks. Likewise, vaccinating healthcare workers decreases transmission risk and is associated with lower patient mortality rates, particularly in long-term care facilities. Increasing air changes, ultraviolet irradiation, and portable HEPA filtration units may also decrease transmission rates but their marginal benefit relative to current healthcare ventilation standards has yet to be established.

SUMMARY

Practical strategies to prevent nosocomial respiratory viral infections include maximizing staff and patient influenza and SARS-CoV-2 vaccination rates and implementing routine masking during patient interactions when community incidence is high.

Molecular detection of SARS-CoV-2 and medically important respiratory and gastrointestinal virus pathogens on Thai currency

Fomite-mediated viral transmission through using cash might be a potential risk to human health. Persistence of SARS-CoV-2, and other medically important viruses was investigated. A total of 300 samples (i.e., 150 banknotes and 150 coins) were randomly collected from nineteen fresh markets distributed across seventeen districts of Bangkok, Thailand. Every banknote or coin was entirely swabbed and generated a total of 100 pool samples. Total viral nucleic acid was extracted and subjected for multiplex real-time qRT-PCR using Allplex™ SARS-CoV-2/FluA/FluB/RSV assay and Allplex™ GI-virus assay. The results revealed detection rate of 4% (4/100), and they were only detected in banknote pooled samples. Two samples collected from fish shops tested positive for SARS-CoV-2 (2%, 2/100); meanwhile, two samples (2%, 2/100) from pork and chicken shops tested positive for rotavirus A. None of pool samples were detected for influenza A and B viruses, respiratory syncytial virus, norovirus genogroup I and II, adenovirus, astrovirus, and sapovirus. Phylogenetic analysis demonstrated that rotavirus A belonged to genotype G8; meanwhile, SARS-CoV-2 resembled omicron GRA JN.1 sub variant. Our finding is the first report for demonstrating the presence of SARS-CoV-2 and rotavirus A in Thai banknotes on real-world situation, implying the potential risk to human health and safety.

All-atom virus simulations to tackle airborne disease

We briefly review the latest computational studies focused on modeling viruses with classical all-atom (AA) molecular dynamics. We report on the challenges, current solutions, and ongoing developments in constructing and simulating whole viruses, and discuss unique insights derived from AA mesoscale simulations that cannot be achieved by other means. Finally, we present new opportunities in computational virology to understand viral aerostability within the context of respiratory disease transmission. Overall, we highlight the value of large-scale AA simulation and champion the need for increased interdisciplinary collaboration to generate novel insights and guide future research in respiratory disease.

SARS-CoV-2 variants retain high airborne transmissibility by different strategies

SARS-CoV-2 variants evolve to balance immune evasion and airborne transmission, yet the mechanisms remain unclear. In hamsters, first-wave, Alpha, and Delta variants transmitted efficiently via aerosols. Alpha emitted fewer viral particles than first-wave virus but compensated with a lower infectious dose (ID50). Delta exhibited higher airborne emission but required a higher ID50. A fall in airborne emission of infectious Delta virus over time after infection correlated with a decrease in its infectivity to RNA ratio in nasal wash and a decrease in contagiousness to sentinel animals. Omicron subvariants (BA.1, EG.5.1, BA.2.86, JN.1) displayed varying levels of airborne transmissibility, partially correlated with airborne emissions. Mutations in the non-spike genes contributed to reduced airborne transmissibility, since recombinant viruses with spike genes of BA.1 or JN.1 and non-spike genes from first-wave virus are more efficiently transmitted between hamsters. These findings reveal distinct viral strategies for maintaining airborne transmission. Early assessment of ID50 and aerosolized viral load may help predict transmissibility of emerging variants.

Ultrabreathable Open-Cell Hierarchical Pore Structure for Radiative Cooling Protective Membranes

Personal protective clothing is essential in biochemical threat environments, however balancing protection, thermal comfort, and breathability remains a significant challenge. This work introduces a novel, skin-friendly ultrabreathable radiative cooling protective membrane (Ub-RCPM), which is developed via a one-step evaporation-induced pore formation process. The sequential evaporation of solvent and nonsolvent during the process endows an ultrabreathable open-cell hierarchical pore structure. By adjusting the open-cell size, Ub-RCPM simultaneously offers high protection, moisture permeability, and passive radiative cooling. The hierarchical pore structure demonstrates a sunlight reflectivity of 94.79% and an infrared emissivity of 94.53% through the infrared atmospheric window, which enables efficient passive cooling. Its open-cell structure enables a water vapor transmission rate of 8904.59 g m-2 day-1, 3.5 times higher than that of commercial protection clothing. Additionally, the submicron pores provide a filtration efficiency of 99.1% for 75 nm aerosols. The combination of radiative cooling and ultrahigh breathability enables Ub-RCPM to a temperature lower than commercial protective clothing by 9.6-16.5 °C in real-world conditions. This presents a groundbreaking approach for the design of future thermal comfortable personal protective clothing.

Influence of kindergarten dormitory bed layout on the proximity propagation characteristics of exhaled pollutants

Kindergarten dormitories are indoor napping areas where preschool children spend extended periods nearby, making them high-risk environments for the transmission of respiratory diseases. To understand the transmission characteristics of respiratory pollutants, particularly CO2 and simulated cough aerosols between adjacent beds, two common bed layouts in kindergartens were investigated: three beds of staggered height (TBSH) and three beds of uniform height (TBUH). The experiments measured CO2 and PM2.5 concentrations (using liquid aerosols generated by an ultrasonic nebulizer as surrogates for cough particles) in the breathing zone of mannequins under different ventilation modes (on and off) and sleeping postures (lying face up and on the right side). The results showed that when ventilation was off, CO2 concentration near the head of each bed reached nearly 1,000 ppm within 60 min. When ventilation was on, CO2 concentration was diluted to ambient levels within 3.3 min. However, when the ventilation was on, aerosols exhibited different propagation characteristics compared to CO2. While CO2 was rapidly diluted, aerosols accumulated downstream and formed high-concentration zones at adjacent downstream beds. These findings visualize the potential aerosol transmission pathways between beds in kindergarten dormitories and highlight the limitations of using CO2 as an aerosol transmission tracer. The study found that increasing bed heights along the ventilation airflow direction effectively reduced downstream aerosol concentrations and compensated for the insufficient horizontal distance in kindergarten dormitories. Kindergarten design standards should consider local dilution efficiency in the breathing zone, and bed layouts should be integrated with the ventilation system to ensure air velocities exceed 0.01 m/s near the head, thereby reducing the residence time of pollutants in the breathing zone.

An Atmospheric Chemistry Perspective on Airborne Micro- and Nanoplastic Particles

Micro- and nanoplastic particles (MNPPs) are emerging pollutants with significant environmental impacts due to their persistence, increasing concentrations, and potential health risks. Most MNPP studies have focused on identifying, quantifying, and assessing their ecotoxicological impacts in water or soil. However, the atmosphere is crucial in transporting and chemically transforming MNPPs. Further, well-established aerosol particle characterization techniques are underutilized and inconsistently applied in existing atmospheric MNPP studies. This perspective synthesizes the existing literature and addresses future research needs unique to atmospheric MNPPs, highlighting the need to bridge the microplastics and atmospheric aerosol communities to better understand their sources, chemical transformations, transport mechanisms, as well as their health effects and ecological impacts, which differ from those in soil and water. Advancing research in these areas requires standardized methods and a multidisciplinary approach to comprehensively assess MNPP interactions across environmental compartments, providing essential insights into their environmental fate and risks.

The intricate interplay among microbiota, mucosal immunity, and viral infection in the respiratory tract

The mucosal system serves as the primary barrier against respiratory diseases and plays a crucial role in combating viral infections through mucosal immunity. The resident microbial community constitutes the main component of the mucosal system and exerts a significant inhibitory impact on the invasion of exogenous agents. However, the precise relationship between resident microbiota, mucosal immunity, and viral infections remains incomplete. This review aims to summarize the regulatory interactions between the resident microbiota of the mucosal system and innate immune components such as mucosal immunity and trained immunity. By clarifying these complex relationships, this review seeks to identify potential targets for augmenting respiratory disease prevention strategies and developing novel vaccine formulations. Furthermore, we propose the possibility of integrating the fields of microbiome-based therapeutics and vaccine development to create multifunctional vaccine formulations capable of targeting mucosal immunity induction. Such an approach holds great potential in offering novel pathways and strategies for the prevention and treatment of respiratory diseases.

Aerosol emission and exposure in non-invasive ventilation

From the beginning of the COVID-19 pandemic, there has been concern among clinicians whether the use of high-flow nasal cannula (HFNC) and continuous positive airway pressure (CPAP) contributes to aerosol generation and consequently spreading of pathogens. Most guidelines still classify these treatments as high-risk aerosol-generating procedures. The aim of this study was to evaluate differences in aerosol emissions and exposure with CPAP and HFNC compared to no breathing aid (NBA). Aerosol emissions of 16 healthy volunteers using CPAP, HFNC and NBA were measured with a portable aerosol spectrometer. During each measurement, the volunteers were instructed consecutively to breathe normally, breathe deeply, cough and read aloud a predefined text. The Wilcoxon signed-rank test was used in statistical analysis. Non-invasive ventilation (CPAP, HFNC) does not produce significantly more aerosol than the same respiratory activities without a breathing aid (median CPAP-NBA - 4.54 1/L, p = 0.816, and HFNC-NBA 2.27 1/L, p = 0.244), deep breathing (median CPAP-NBA - 2.27 1/L, p = 0.378 and HFNC-NBA 4.55 1/L, p = 0.623), speaking (median CPAP-NBA 0 1/L, p = 0.0523 and HFNC-NBA 9.09 1/L, p = 0.0140), or coughing (median CPAP-NBA - 17.31 1/L, p = 0.587 and HFNC-NBA 1.92 1/L, p = 0.365). The results indicate that both CPAP and HFNC have no clinically meaningful impact on aerosol emission. Therefore, the use of CPAP or HFNC does not expose healthcare personnel to greater concentrations of aerosols when compared to normal breathing in healthy participants.

Particulate Matter Exposure and Viral Infections: Relevance to Highly Polluted Settings such as Ulaanbaatar, Mongolia

PURPOSE OF REVIEW

Particulate matter (PM), a ubiquitous significant component of the ambient air pollution mixture, significantly contributes to increased global risk for chronic cardiopulmonary diseases, acute hospitalizations, and deaths. One of the causes of this increased risk is because PM exposure increases the incidence and severity of respiratory infections. The respiratory system is particularly vulnerable to air pollution and its impact on infection as it is a key site for exposure both to inhaled pollutants and infectious microbes or viruses. This review examines the current understanding of how PM affects antiviral host defense responses and possible underlying mechanisms.

RECENT FINDINGS

While numerous studies have associated adverse health outcomes with combined or sequential exposure to inhaled pollutants and viruses, defining causal relationships and mechanisms remains limited. Particularly limited, are contemporary data focuses on low- and middle-income countries, including heavily polluted regions such as Ulaanbaatar, Mongolia. This manuscript focuses on how (1) PM, serving as a carrier for viruses, enhances the transmission of viruses; (2) PM impairs immune defense to viruses; and (3) PM impacts epithelial cell functions to exacerbate viral infections. Given the significant public health hazards on PM, particularly in heavily polluted regions such as Southeast Asia, Middle East and Africa, it is critical to define specific mechanisms of PM on respiratory infection and how their impact may differ in these highly polluted regions. Ultimately, this could devise future public health measures and interventions to limit this substantial public health risk.

Biosecurity Implications, Transmission Routes and Modes of Economically Important Diseases in Domestic Fowl and Turkey

The poultry industry is a critical source of affordable protein worldwide; however, it faces continuous threats from various poultry diseases that significantly impact public health, economic stability, and food security. Knowledge of and examination of the transmission routes, risk factors, and environmental survival characteristics of the most important pathogens affecting poultry populations, as well as the importance of strict biosecurity, are pivotal. Transmission routes are split into direct and vector-borne pathways, and indirect ways, which include infections via contaminated surfaces and vector-borne pathways, including insects and rodents. Avian influenza virus and Newcastle disease virus spread through respiratory droplets, and their transmission risk increases with increasing stocking density. While other pathogens (e.g., infectious bursal disease virus and Salmonella spp.), to persist long-term in the environments, for example, feed and litter, increasing the probability to persist long-term in the environments, for example, feed and litter, increasing the probability of infection. The long-term resilience of pathogens in multiple pathogens in various environmental conditions highlights the role of biosecurity, sanitation, and hygiene controls in preventing disease outbreaks. High stocking density in production systems, suboptimal ventilation, and inadequate biosecurity controls further increase transmission risks. This paper summarizes important disease transmissions and reinforces the need for strict biosecurity protocols and routine health monitoring to prevent the spread of pathogens within and beyond poultry facilities. These strategies can support safe poultry production, address growing global demand, and ensure food safety and public health.

Characterization of respiratory particles released during continuous speech and its relation to mask performance

Revealing the physicochemical characteristics of exhaled particles is essential for understanding and efficiently mitigating the airborne spread of contagious human illnesses. Among the most pivotal factors, the number size distribution of emitted particles plays a crucial role when considering atmospheric dispersion. This study focuses on submicron particles emitted during speaking, with particular attention on the changes over time. Moreover, the real-world (source control) efficiency of three types of commonly used facemasks (FFP2, surgical and 2-layer cotton mask) under in vivo conditions was studied. A specially designed cabin ensured a controlled environment, where a set of experiments was conducted on 28 participants. Our findings revealed no substantial variability in the number size distribution among different individuals and pitches. However, the quantity of emitted particles varied significantly among individuals, with differences reaching nearly two orders of magnitude. Additionally, the emitted number of particles strongly depended on the speaking volume, decreasing as speech volume was reduced. Submicron particles originating from the lungs and upper airways exhibited a consistent bimodal pattern, with peaks around 300 nm and below 100 nm. FFP2 and surgery masks worn by the subjects demonstrated robust performance in real-world conditions characterized by 80% source control efficiency even for the smallest particle size ranges tested. At the same time, textile masks yielded less favourable results of 50-60% source control efficiency.

Encephalitis-predominant Nipah virus outbreaks in Kerala, India during 2024

Nipah virus (NiV) is a highly pathogenic zoonotic paramyxovirus with significant public health concern. Since 2018, Kerala, India, has experienced NiV outbreaks with variable clinical manifestations ranging from acute encephalitis syndrome (AES) to acute respiratory distress syndrome (ARDS). Recently, we observed two NiV outbreaks in Malappuram, Kerala, India during 2024, with AES as the predominant clinical manifestation in July and September 2024. Among all close contacts screened no secondary transmission of NiV was observed. The data from NiV outbreaks of Kerala state indicated that AES-predominant outbreaks (2019, 2021, and 2024) had shown no human-to-human transmission compared to ARDS-predominant outbreaks (2001, 2007, 2018, and 2023). Early detection, efficient containment, and improved surveillance were important measures in preventing secondary transmission. The two spill over events of NiV in 2024 reiterates the need for enhancing the surveillance of NiV among ARDS cases for timely case management and containment of the outbreak. In view of this, a network of seventeen Virus Research and Diagnostic Laboratories (VRDLs) was established for surveillance of severe acute respiratory illnesses in West Bengal and Kerala states of India. The continued public health preparedness and community awareness would help to prevent future outbreaks.

Aerosol particles released from grit chambers of nine urban wastewater treatment plants in typical regions: Fugitive characteristics, quantitative drivers, and generation process

The flow through the grit chamber is non-biochemically treated wastewater, which contains microorganisms mainly from the source of wastewater generation. There are limited reports on aerosol particles generated by grit chambers compared with those produced by biochemical treatment tanks. This study analyzed the fugitive characteristics of aerosol particles produced in grit chambers at nine wastewater treatment plants in three regions of China. There were 160.41-432.13 μg/m3 of total particles and 455 ± 34-2181 ± 221 CFU/m3 of bacteria in aerosol particles. The chemicals in aerosol particles contained 7.35-53.70 μg/m3 of total organic carbon and 36.10-227.94 μg/m3 of water-soluble inorganic ions. The aerated grit chambers produced significantly more aerosol particles than the vortex-type grit chambers. Indoor treatment facilities were more prone to aerosol particle accumulation than outdoor facilities. The microorganisms in wastewater were the main contributing source of dominant microorganisms in aerosol particles, with a degree of explanation of 73.33 % ± 35.56 %. Mantel analysis and the partial least squares path modeling determined that the components and biodiversity of wastewater were direct determinants of aerosol emission levels and biodiversity, respectively. Geographic regions contributed to the differences in aerosol particles, primarily indirectly by affecting the components of wastewater. The bubble bursting trajectory simulation experiment simulated the bioaerosol generation process in aerated grit chambers and predicted droplet behaviours. A higher number of small film droplets corresponded to a higher concentration of bioaerosols. Arcobacter, Aeromonas, Acinetobacter, and Flavobacterium were the major pathogenic genera in aerosol particles produced by grit chambers. The annual probability of infection and the disease burden of these pathogenic bacteria cannot be ignored. This study provides a scientific basis for further understanding of aerosol particle generation and potential hazards in grit chambers of wastewater treatment plants.

Environmental fate of antibiotic resistance genes in livestock farming

As emerging environmental pollutants, antibiotic resistance genes (ARGs) are prevalent in livestock farms and their surrounding environments. Although existing studies have focused on ARGs in specific environmental media, comprehensive research on ARGs within farming environments and their adjacent areas remains scarce. This review explores the sources, pollution status, and transmission pathways of ARGs from farms to the surrounding environment. Drawing on the "One Health" concept, it also discusses the potential risks of ARGs transmission from animals to human pathogens and the resulting impact on human health. Our findings suggest that the emergence of ARGs in livestock farming environments primarily results from intrinsic resistance and genetic mutations, while their spread is largely driven by horizontal gene transfer. The distribution of ARGs varies according to the type of resistance genes, seasonal changes, and the medium in which they are present. ARGs are disseminated into the surrounding environment via pathways such as manure application, wastewater discharge, and aerosol diffusion. They may be absorbed by humans, accumulating in the intestinal microbiota and subsequently affecting human health. The spread of ARGs is influenced by the interplay of microbial communities, antibiotics, heavy metals, emerging pollutants, and environmental factors. Additionally, we have outlined three control strategies: reducing the emergence of ARGs at the source, controlling their spread, and minimizing human exposure. This article provides a theoretical framework and scientific guidance for understanding the cross-media migration of microbial resistance in livestock farming environments.

Airborne Influenza Virus Surveillance Platform Using Paper-Based Immunosensors and a Growth-Based Virus Aerosol Concentrator

The measurement of respiratory viruses in indoor air is critical for effectively preventing the spread of diseases. This is typically accomplished by counting the nucleic acids or plaques of air-sampled viruses. Herein, we present a growth-based airborne virus surveillance (G-AVS) platform based on paper-based electrochemical immunosensors for targeting hemagglutinin (HA) and nucleoprotein (NP), and water-condensation air sampling for the quantitative measurement of airborne influenza viruses. The measurements, compared with RT-qPCR, demonstrated consistency between the two. In the measurements of airborne influenza viruses conducted in an elementary school using G-AVS, 23% (4/17) of indoor air samples were positive, with concentrations ranging from 1.7 × 104 to 1.6 × 106 gene copies/m3, while losses in the HA relative to NP were 48-75% at a relative humidity of 27.0-36.8% and 60 min air sampling, similar to infectivities reported in the literature. This platform has the potential for rapid and cost-effective airborne virus measurement.

Ultraviolet radiation vs air filtration to mitigate virus laden aerosol in an occupied clinical room

Mitigation measures against infectious aerosols are desperately needed. We aimed to: 1) compare germicidal ultraviolet radiation (GUV) at 254 nm (254-GUVUpper-Room) and 222 nm (222-GUVWhole-Room) with portable high efficiency particulate air (HEPA) filters to inactivate/remove airborne bacteriophage ϕX174, 2) measure the effect of air mixing on the effectiveness of 254-GUVUpper-Room, and 3) determine the relative susceptibility of ϕX174, SARS-CoV-2, and Influenza A(H3N2) to GUV (254 nm, 222 nm). A nebulizer generated ϕX174 laden aerosols in an occupied clinical room (sealed-low flow). Mitigation devices (3 commercial GUV devices, HEPA-470m3/hr-class H13 filter) were compared by counterbalanced experimental design with negative (no mitigation) control. Viral inactivation was determined by air sampling (SartoriusMD8 and Gilair5). Environmental physical properties (airflow, particle matter, GUV irradiance, temperature and humidity) were also characterized. The effect of improving air mixing on the efficacy of 254-GUVUpper-Room devices was systematically explored by adding fans. The relative susceptibility of SARS-CoV-2, Influenza A(H3N2) and ϕX174 were assessed by exposure to 254 nm and 222 nm wavelength radiation in a 82 L chamber. 254-GUVUpper-Room with highest irradiance (Philips UV-C WL345W) resulted in highest calculated equivalent air changes per hour (eACH) of 8.18 ± 0.74 (hr-1). This increased to 19.20 ± 2.45 (hr-1) with the addition of 2 fans. HEPA filtration achieved 11.10 ± 1.25 (hr-1). For 254 nm GUV rank order (most-to-least) of susceptibility was SARS-CoV-2, ϕX174, Influenza A(H3N2), and for 222 nm GUV SARS-CoV-2, Influenza A(H3N2), ϕX174. GUV effectively inactivates virus laden aerosol in poorly ventilated clinical environments. Efficacy is improved by increasing airflow. HEPA performance is superior to GUV under low flow conditions.

Methodology of Epidemic Risk Analysis in the Naval Military

This review of the literature examines diseases and pathogen characteristics on military vessels, in order to improve the success of missions on a boat. Our aim is to understand the spread of disease, aiming to maximize biological resilience and hopefully eliminate outbreaks. Keyword research was conducted from various sources of information, including scientific publications, theses, public health organization websites, and clinical trials. A synthesis of bacterial, viral, fungal, and parasitosis characteristics was established, and a risk prioritization index was defined, based on contagiousness (basic reproduction number (R0)) and clinical severity. For instance, COVID-19 was assessed as moderately contagious, with critical severity, and Influenza A H1N1 as having a minor level of contagiousness with critical severity, resulting in a level two out of three risk prioritization index. This approach demonstrates that while diseases have numerous characteristics, a method for classifying them by isolating specific criteria and prioritizing them could be proposed. In conclusion, further work is needed to analyze onboard operator activities and develop simulation models related to pathogen characteristics.

Effectiveness of Preprocedural Mouthwashes: A Triple-Blind Randomised Controlled Clinical Trial

OBJECTIVES

Bioaerosols generated during dental treatment are considered to be potentially carriers of infectious respiratory pathogens. The use of preprocedural mouthwashes has been suggested to reduce microbial load prior to dental surgery procedures. However, limited evidence on the effectiveness of preprocedural mouthwashes regarding mitigating respiratory pathogens exists. The aim of this clinical trial is to determine and compare the effectiveness of 3 preprocedural mouthwashes recommended by the Department of Health of the Hong Kong Special Administrative Region in the mitigation of respiratory pathogens during dental care in pandemic times.

METHODS

In all, 228 participants were block-randomised to three groups based on preprocedural mouthwash used: povidone-iodine, hydrogen peroxide, and chlorhexidine digluconate. Participants, operators, and assessors were blinded to the assigned mouthwashes (triple-blind). Saliva was assessed for the presence of a number of respiratory pathogens (19 viruses including SARS-CoV-2). Changes in the prevalence and mean number of "any" pathogen present following mouthwash use were determined.

RESULTS

Overall, the prevalence of any detected respiratory viral pathogens in the preprocedural saliva was 3.5% as compared to the postprocedural saliva: 1.3% (P = .034). The mean (SD) number of viruses was significantly lower following preprocedural mouthwash use, from 0.04 (0.18) to 0.01 (0.11) (P = .025). No significant differences were observed in the downward change (∆) of any detected virus (prevalence) (P = .155) or in the reduction of the mean number (∆) of any detected virus in the postprocedural saliva compared to preprocedural saliva of participants with respect to mouthwash used (P = .375).

CONCLUSIONS

The practice of using preprocedural mouthwash, as recommended by the government of Hong Kong, was effective in reducing the number of respiratory pathogens present during dental aerosol-generating treatment. This study lends support for official policy on use of preprocedural mouthwashes, which has significant implications for practice and policy during pandemics.

Indoor air quality and symptoms of acute respiratory infections and gastrointestinal issues in children and employees in day-care nurseries

BACKGROUND

Children attending day-care centers (DCCs) experience more infections than those cared for at home and DCC employees have high sickness absence rates. This study aimed to investigate the association between indoor air quality and absenteeism among children and staff in DCCs.

METHODS

CO2 levels, relative humidity (RH), and temperature were continuously measured in 22 DCCs over 3 winter months. Simultaneously, absenteeism due to sickness was recorded for 721 children and 213 employees. In 11 DCCs, staff received training to improve ventilation.

RESULTS

The median CO2 concentration, RH, and temperature were 818 ppm, 38.7%, and 20.8 °C, respectively. Acute respiratory infections (ARIs) accounted for 42% of child absenteeism and 53% of staff absenteeism, while gastrointestinal symptoms (GI) were responsible for 24.7% and 27.3% of absenteeism in children and staff, respectively. No significant association was found between ARI absenteeism and CO2 concentration, RH, or temperature. However, a significant association was observed between GI and room temperature (P < .05). No significant differences in CO2 concentration or absenteeism were observed between intervention and control groups.

CONCLUSIONS

No statistical evidence was found that ARI absenteeism was associated with the measured indoor air quality parameters. GI for staff and children was significantly associated with room temperature. Absenteeism was not associated significantly with targeted interventions.

Inhalable nanocatalytic therapeutics for viral pneumonia

Pneumonia is a ubiquitous disease caused by viral and bacterial infections, characterized by high levels of reactive oxygen species in inflamed areas. Therapeutic strategies targeting reactive oxygen species levels in pneumonia have limited success due to the intricate nature of lung tissues and lung inflammatory responses. Here we describe an inhalable, non-invasive therapeutic platform composed of engineered cerium-based tannic acid nanozymes bound to a self-assembling peptide. In vitro and in vivo studies show that the nanozyme is internalized mostly by activated macrophages and epithelial cells in the inflamed sites. In the oxidative environments of a mouse model of viral pneumonia, nanozyme aggregates into catalytically active structures that reduce reactive oxygen species levels and inflammatory cytokine production and promote macrophage polarization to the prohealing (M2) phenotype. Moreover, the nanozyme attenuates bacterial inflammation and reduces tissue damage in a mouse viral pneumonia model with secondary bacterial infection. Overall, this nanozyme platform is a promising strategy for treating pneumonia and its associated conditions.

Hidden in plain sight: the impact of human rhinovirus infection in adults

BACKGROUND

Human rhinovirus (HRV), a non-enveloped RNA virus, was first identified more than 70 years ago. It is highly infectious and easily transmitted through aerosols and direct contact. The advent of multiplex PCR has enhanced the detection of a diverse range of respiratory viruses, and HRV consistently ranks among the most prevalent respiratory pathogens globally. Circulation occurs throughout the year, with peak incidence in autumn and spring in temperate climates. Remarkably, during the SARS-CoV-2 pandemic, HRV transmission persisted, demonstrating its resistance to stringent public health measures aimed at curbing viral transmission.

MAIN BODY

HRV is characterised by its extensive genetic diversity, comprising three species and more than 170 genotypes. This diversity and substantial number of concurrently circulating strains allows HRVs to frequently escape the adaptive immune system and poses formidable challenges for the development of effective vaccines and antiviral therapies. There is currently a lack of specific treatments. Historically, HRV has been associated with self-limiting upper respiratory infection. However, there is now extensive evidence highlighting its significant role in severe lower respiratory disease in adults, including exacerbations of chronic airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD), as well as pneumonia. These severe manifestations can occur even in immunocompetent individuals, broadening the clinical impact of this ubiquitous virus. Consequently, the burden of rhinovirus infections extends across various healthcare settings, from primary care to general hospital wards and intensive care units. The impact of HRV in adults, in terms of morbidity and healthcare utilisation, rivals that of the other major respiratory viruses, including influenza and respiratory syncytial virus. Recognition of this substantial burden underscores the critical need for novel treatment strategies and effective management protocols to mitigate the impact of HRV infections on public health.

CONCLUSION

This review examines the epidemiology, clinical manifestations, and risk factors associated with severe HRV infection in adults. By drawing on contemporary literature, we aim to provide a comprehensive overview of the virus's significant health implications. Understanding the scope of this impact is essential for developing new, targeted interventions and improving patient outcomes in the face of this persistent and adaptable pathogen.

Finite mixture models of superspreading in epidemics

Superspreading transmission is usually modeled using the negative binomial distribution, simply because its variance is larger than the mean and it can be long-tailed. However, populations are often partitioned into groups by social, behavioral, or environmental risk factors, particularly in closed settings such as workplaces or care homes. While heterogeneities in infectious histories and contact structure have been considered separately, models for superspreading events that include the joint effects of social and biological risk factors are lacking. To address this need, we developed a mechanistic finite mixture model for the number of secondary infections that unites population partitioning with individual-level heterogeneity in infectious period duration. We showed that the variance in the number of secondary infections is composed of both sources of heterogeneity: risk group structuring and infectiousness. We used the model to construct the outbreak size distribution and to derive critical thresholds for elimination resulting from control activities that differentially target the high-contact subpopulation vs. the population at large. We compared our model with the standard negative binomial distribution and showed that the tail behavior of the outbreak size distribution under a finite mixture model differs substantially. Our results indicate that even if the infectious period follows a bell-shaped distribution, heterogeneity in outbreak sizes may arise due to the influence of population risk structure.

Aerosol Capture for Coupling to Microfluidics: A Miniaturized Low-Cost Device for Size-Resolved Particle Collection

Inhaled aerosols impact human health by depositing harmful species in the lungs (e.g., metals and organic pollutants) and act as a key pathway for airborne disease transmission. Aerosol inhalation is highly size-dependent, with smaller particles (particulate matter <2.5 μm, PM2.5) depositing deeper in the lungs (e.g., alveoli) leading to strong correlations between PM2.5 and mortality, along with other respiratory and cardiovascular diseases. A longstanding challenge for detailed aerosol chemical analysis is that most PM2.5 health studies collect offline samples, which are subsequently analyzed offsite, requiring high-cost collectors and significant downstream effort and cost. Herein, we present a low-cost, miniature 3D-printed impactor coupled to a microfluidic channel to allow for downstream analysis of PM in liquid. After size-segregated collection of airborne particles within the device, water is flowed through a microfluidic channel that resuspends insoluble particles or dissolves soluble particles. Size-dependent collection efficiencies (50% cutoff diameters, d50's) for the supermicron (PM>1) impactor were 0.8 and 1.0 μm using monodisperse (polystyrene latex spheres) and polydisperse (red-fluorescent spheres) standards, respectively. Coarse (PM>2.5) impactor d50's were 2.4 and 2.6 μm, respectively. Optical photothermal infrared (O-PTIR) and Raman microspectroscopy confirmed collected particle composition. The sizes of re-entrained PSLs (1, 1.25, and 1.5 μm) were measured to have diameters of 1.0, 1.2, and 1.5 μm, respectively, with a Coulter Counter, indicating the successful downstream analysis of collected particles without modification during impaction and resuspension. Soluble particles (ammonium sulfate) were dissolved by the flowing water and measured with ion chromatography. This study shows that 3D-printed impactors are capable of collecting particles with a well-defined size cut, as well as nondestructively resuspending and chemically analyzing the particles. These 3D-printed devices are a miniaturized, low-cost (<$2) option that sets the stage for semicontinuous microfluidic analysis of size-selected aerosols to evaluate health impacts ranging from toxin exposure to disease transmission.

Viral Transmission in Sea Food Systems: Strategies for Control and Emerging Challenges

The SARS-CoV-2 pandemic had widespread and severe impacts on both the global economy and human health. Facing the continuously mutating virus, this crisis has heightened concerns among consumers and businesses regarding viral transmission through seafood, particularly in the face of emerging, unknown viruses, underscoring our preparedness gaps. This review provides a succinct overview of the survival mechanisms of prevalent viruses in seafood, examines potential transmission pathways to humans during seafood processing, and discusses strategies for mitigating their spread throughout the seafood supply chain. Furthermore, the discussion highlights emerging trends in innovative antiviral technologies aimed at enhancing food safety. Person-to-person transmission remains the most likely source of infection within the supply chain. Therefore, it is still imperative to adhere to the implementation of standard processes, namely good manufacturing practices (GMP) and good hygiene practices (GHP), in the seafood business. In light of the significant losses caused by this crisis and the persistent presence of various viruses within the seafood supply chain, efforts are needed to implement predictive and preventive measures against potential emerging viruses. Future research should focus on monitoring and limiting viral transmission by integrating Industry 4.0 applications, smart technologies, and antiviral packaging, maximizing the potential of these emerging solutions.

Extending a COVID-19 Job Exposure Matrix: The SARS-CoV-2 or COVID-19 Job Exposure Matrix Module (SCoVJEM Module) for Population-Based Studies

The risk of workplace SARS-CoV-2 transmission is increased by aerosolization or droplets and increased respiratory rates or increased viral stability in cold environments. Few methods exist for identifying occupational risks of SARS-CoV-2 transmission. We extended a SARS-CoV-2 job exposure matrix (JEM) into four dimensions, talking loudly (Loud) (very loud, loud, somewhat loud, or not), physical activity (PA) (high, medium or low), and cold (Cold) (cold or not) and hot environments (Hot) (hot or not), using data from the Occupational Information Network (O*NET) and a priori questions for each and noise measurements for 535 occupations. We classified 70%+ occupations as loud or very loud (74.6%); whereas 13.8% were high PA, 18.5% exposed to cold, and 23.7% exposed to hot temperatures. Applying to California 2019 workforce data to explore by race/ethnicity and sex, we found 21.2% worked in very loud and 12.6% in high PA occupations and 15.7% in cold and 17.8% hot environments. Latino workers were highly represented in very loud and high PA levels among farming (83.8 and 78.4%) and construction (58.7% and 50.3%). More males worked in each highest exposure level than females. This JEM provides aerosol transmission proxies for COVID-19 risk factors and merits investigation as a tool for epidemiologic studies.

Intestinal-pulmonary axis: a 'Force For Good' against respiratory viral infections

Respiratory viral infections are a major global public health concern, and current antiviral therapies still have limitations. In recent years, research has revealed significant similarities between the immune systems of the gut and lungs, which interact through the complex physiological network known as the "gut-lung axis." As one of the largest immune organs, the gut, along with the lungs, forms an inter-organ immune network, with strong parallels in innate immune mechanisms, such as the activation of pattern recognition receptors (PRRs). Furthermore, the gut microbiota influences antiviral immune responses in the lungs through mechanisms such as systemic transport of gut microbiota-derived metabolites, immune cell migration, and cytokine regulation. Studies have shown that gut dysbiosis can exacerbate the severity of respiratory infections and may impact the efficacy of antiviral therapies. This review discusses the synergistic role of the gut-lung axis in antiviral immunity against respiratory viruses and explores potential strategies for modulating the gut microbiota to mitigate respiratory viral infections. Future research should focus on the immune mechanisms of the gut-lung axis to drive the development of novel clinical treatment strategies.

Design, synthesis, and antiviral activity of fragmented-lapatinib aminoquinazoline analogs towards SARS-CoV-2 inhibition

The severe impact of COVID-19 on global health and economies highlights the critical need for innovative treatments. Recently, lapatinib, a drug initially used for breast cancer, has been identified as a potential inhibitor of the main protease (Mpro) of SARS-CoV-2, meriting further investigation. Utilizing rational design strategies and guided by MD simulations, we developed novel aminoquinazoline analogs based on fragmented lapatinib's structure. Preliminary computational screenings identified promising candidates, which were synthesized using a concise 3-4 step process. In vitro assays demonstrated notable antiviral efficacy against SARS-CoV-2-infected cells for all analogs, with Bb1 showing an EC50 of 1.10 μM and significantly lower toxicity (13.55 % at 50 μM) compared to lapatinib. Further studies confirmed that these analogs effectively inhibit SARS-CoV-2 Mpro, with Bb7 displaying the highest activity. MD simulations revealed that Bb7 achieves stability within the Mpro binding pocket through interactions with specific residues. These findings indicate that aminoquinazoline analogs hold significant promise as therapeutic candidates for COVID-19.

Innate immune sensing of rotavirus by intestinal epithelial cells leads to diarrhea

Diarrhea is the predominant symptom of acute gastroenteritis resulting from enteric infections and a leading cause of death in infants and young children. However, the role of the host response in diarrhea pathogenesis is unclear. Using rotavirus and neonatal mice as a model, we found that oral inoculation of UV-inactivated replication-defective rotavirus consistently induced watery diarrhea by robust activation of cytosolic double-stranded RNA sensing pathways and type III interferon (IFN-λ) secretion. Diarrhea was significantly diminished in mice lacking the IFN-λ receptor. Mechanistically, IFN-λ signaling downregulates the expression of Dra, a chloride and bicarbonate exchanger, which contributes to reduced water absorption. We confirmed these findings in mice inoculated with reovirus, as well as in donor-derived human intestinal organoids and human biopsy samples. Our data highlight a mechanism of rapid diarrhea induction by host innate immune sensing in the gastrointestinal tract and suggest that diarrhea induction is an active host defense strategy to eliminate the pathogen.

Air, surface, and wastewater surveillance of SARS-CoV-2; a multimodal evaluation of COVID-19 detection in a built environment

BACKGROUND

Environmental surveillance of infectious organisms holds tremendous promise to reduce human-to-human transmission in indoor spaces through early detection.

OBJECTIVE

In this study we determined the applicability and limitations of wastewater, indoor high-touch surfaces, in-room air, and rooftop exhaust air sampling methods for detecting SARS-CoV-2 in a real world building occupied by residents recently diagnosed with COVID-19.

METHODS

We concurrently examined the results of three 24-hour environmental surveillance techniques, indoor surface sampling, exhaust air sampling and wastewater surveillance, to the known daily census fluctuations in a COVID-19 isolation dormitory. Additionally, we assessed the ability of aerosol samplers placed in the large volume lobby to detect SARS-CoV-2 multiple times per day.

RESULTS

Our research reveals an increase in the number of individuals confirmed positive with COVID-19 as well as their estimated human viral load to be associated with statistically significant increases in viral loads detected in rooftop exhaust aerosol samples (p = 0.0413), wastewater samples (p = 0.0323,), and indoor high-touch surfaces (p < 0.001)). We also report that the viral load detected in lobby aerosol samples was statistically higher in samples collected during presence of occupants whose COVID-19 diagnostic tests were confirmed positive via qPCR compared to periods when the lobby was occupied by either contact-traced (suspected positive) individuals or during unoccupied periods (p = 0.0314 and <2e-16).

SIGNIFICANCE

We conclude that each daily (24h) surveillance method, rooftop exhaust air, indoor high-touch surfaces, and wastewater, provide useful detection signals for building owner/operator(s). Furthermore, we demonstrate that exhaust air sampling can provide spatially resolved signals based upon ventilation exhaust zones. Additionally, we find that indoor lobby air sampling can provide temporally resolved signals useful during short duration sampling periods (e.g., 2-4 hours) even with intermittent occupancy by occupants diagnosed with COVID-19.

IMPACT

Our research demonstrates that aerosol sampling can detect COVID-19 positive individuals in a real world lobby setting during very short occupancy periods. We demonstrate the effectiveness of rooftop exhaust aerosol, surface, and wastewater environmental surveillance in monitoring viral load in building occupants, both at the building scale and with ventilation zone-level resolution for aerosols. We provide actionable data for researchers, health officials and building managers who seek to determine which monitoring method is best for their building or study. This study is relevant in the fields of epidemiology, exposure sciences, biomonitoring, virology, public health, and healthy building design and management.

Global meta-analysis of short-term associations between ambient temperature and pathogen-specific respiratory infections, 2004 to 2023

BackgroundAmbient temperature may affect respiratory health, while the temperature sensitivity of respiratory infections may be pathogen-dependent.AimsWe sought to explore pathogen-specific associations between ambient temperature and respiratory infections.MethodsWe searched nine databases for a random-effects meta-analysis to pool the relative risk (RR) of respiratory infection by pathogen per 1° C temperature rise, compared to populations unexposed to the same temperature. We conducted pathogen-specific analyses, sensitivity analyses, subgroup analyses and meta-regression.ResultsA total of 137 studies were eligible for meta-analysis. The pooled and single-study estimates revealed that the incidence of respiratory syncytial virus (RR = 0.14; 95% confidence interval (CI): 0.09-0.23), influenza virus (IV) (RR = 0.40; 95% CI: 0.27-0.61), human metapneumovirus (RR = 0.48; 95% CI: 0.32-0.73), human coronavirus (HCoV) (RR = 0.21; 95% CI: 0.07-0.61) and SARS-CoV-2 (RR = 0.52; 95% CI: 0.35-0.78) decreased per 1° C temperature rise, while that of human parainfluenza virus (HPIV) (RR = 2.35; 95% CI: 1.46-3.77), human bocavirus (HBoV) (RR = 1.86; 95% CI: 1.04-3.32) and MERS-CoV (RR = 1.05; 95% CI: 1.04-1.07) increased. The risk of infection was lower for IVA, IVB, HCoV-229E and HCoV-OC43, while HPIV-3, and HBoV-1 were at increased risk. The risk of Streptococcus pyogenes pharyngitis (RR = 0.46; 95% CI: 0.30-0.69) decreased per 1° C temperature rise, while Pseudomonas aeruginosa (RR = 1.04; 95% CI: 1.03-1.05) and Legionella pneumophila infections (RR = 2.69; 95% CI: 1.11-6.53) increased.ConclusionsTemperature sensitivity of respiratory infections can vary with the specific pathogen type and subtype that causes the infection. As the climatic conditions will become warmer, public health policy makers should act to develop pathogen adaptation strategies.

Biosecurity and Biocontainment for Ruminant Respiratory Disease

Respiratory disease in cattle and small ruminants is caused by various factors, including inadequate biosecurity and biocontainment. Biosecurity and biocontainment depend on good husbandry. Testing on arrival and quarantining for 42 to 56 days could improve biosecurity. Controlling visitors and vehicles, maintaining good air quality, and ensuring optimal passive immunity transfer are critical. Endemic respiratory agents are unlikely to transmit beyond 10 m, but environmental factors can affect this. Endemic viruses have a high R0, so achieving high herd immunity is important to limit transmission. While vaccination is an important biosecurity tool, it is not a substitute for other practices.

Indoor bioaerosols and asthma: Overview, implications, and mitigation strategies

Aerosolized particles with a biological origin are called bioaerosols. Bioaerosols from plants, animals, fungi, bacteria, and viruses are an important class of environmental exposures that are clinically relevant to asthma. However, there are important differences in the pathways by which various bioaerosols affect asthma. Additionally, differences in individual susceptibility to different bioaerosols affect exposure reduction and mitigation strategies. Strategies to reduce exposures to potential triggers of asthma are routinely considered as part of standard clinical care and asthma management guidelines. Ventilation standards in buildings may reduce bioaerosol exposure for everyone, but they are not necessarily designed specifically to protect patients with asthma. Direct measurement of a bioaerosol is not generally necessary for practical applications where the relevant source of the bioaerosol has been identified. Different types of bioaerosols can be controlled with similar strategies that prioritize source control (eg, reducing resuspension, integrated pest management, controlling moisture), and these can be supplemented by enhancing air filtration. The goal of this review is to summarize the latest information on bioaerosols, including allergens, fungi, bacteria, and viruses, that have been associated with adverse asthma outcomes and to discuss mitigation options.

SARS-CoV-2 infection primes cross-protective respiratory IgA in a MyD88- and MAVS-dependent manner

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is constantly evolving mutations in the Spike protein to evade humoral immunity. Respiratory tract antiviral IgA antibodies are superior to circulating IgG antibodies in preventing SARS-CoV-2 infection. However, the role of innate immune signals required for the induction of mucosal IgA against SARS-CoV-2 infection is unknown. Here we show that hamsters recovered from ancestral SARS-CoV-2 infection are cross-protected against heterologous SARS-CoV-2 alpha, gamma, delta, and omicron BA.1 variants. Intranasal vaccination with an inactivated whole virus vaccine completely protects hamsters against heterologous SARS-CoV-2 infection. In addition, we show that intranasal boost vaccination of mice recovered from SARS-CoV-2 infection with unadjuvanted Spike protein induces robust levels of respiratory anti-Spike IgA and protects the mice from a heterologous SARS-CoV-2 infection. Furthermore, our findings suggest that MyD88 and MAVS play a role in the induction of the memory IgA response following an intranasal booster with unadjuvanted Spike protein in mice recovered from the SARS-CoV-2 infection. These findings provide a useful basis for the development of cross-protective mucosal vaccines against heterologous SARS-CoV-2 infection.

The role of masks and respirators in preventing respiratory infections in healthcare and community settings

The covid-19 pandemic saw frequent changes and conflicts in mask policies and politicization of masks. On reviewing the evidence, including studies published after the pandemic, the data suggest respirators are more effective than masks in healthcare, but must be continuously worn to be protective. Healthcare and aged care settings amplify outbreaks, so protection of patients and staff is paramount. Most guidelines assume risk is only present during close contact or aerosol generating procedures, but studies show intermittent use of respirators is not protective. New research in aerosol science confirms the risk of infection is widespread in health facilities. In community settings, any mask use is protective during epidemics, especially if used early, when combined with hand hygiene, and if wearers are compliant. Community use of N95 respirators is more protective than surgical masks, which are more protective than cloth masks, but even cloth masks provide some protection. Mask guidelines should be adaptable to the specific context and should account for rising epidemic activity, and whether a pathogen has asymptomatic transmission. The main rationale for universal masking during pandemics is asymptomatic transmission, which means risk of transmission cannot be self-identified. The precautionary principle should be applied during serious emerging infections or pandemics when transmission mode is not fully understood, or vaccines and drugs are not available. If respirators are not available, medical or cloth masks could be used as a last resort. Data exist to support extended use and reuse of masks and respirators during short supply. In summary, extensive evidence generated during the covid-19 pandemic confirms the superiority of respirators and supports the use of masks and respirators in the community during periods of high epidemic activity. Some gaps in research remain, including economic analyses, research in special population groups for whom masking is challenging, and research on countering disinformation.

Quantification of droplet and contact transmission risks among elementary school students based on network analyses using video-recorded data

In elementary schools, immunologically immature students come into close contact with each other and are susceptible to the spread of infectious diseases. To analyze pathogen transmission among students, it is essential to obtain behavioral data. Questionnaires and wearable sensor devices were used for communication behavior and swab sampling was employed for contact behavior. However, these methods have been insufficient in capturing information about the processes and actions of each student that contribute to pathogen transmission. Therefore, in this study, actual behavioral data were collected using video recordings to evaluate droplet and contact transmission in elementary schools. The analysis of communication behavior revealed the diverse nature of interactions among students. By calculating the droplet transmission probabilities based on conversation duration, the risk of droplet transmission was quantified. In the contact behavior, we introduced a novel approach for constructing contact networks based on contact history. According to this method, well-known items, such as students' desks, doors, and faucets, were predicted to be potential fomite. In addition, students' shirts and shared items with high contact frequency and high centrality metrics in the network, which were not evaluated in swab sampling surveys, were identified as potential fomites. The reliability of the predictions was demonstrated through micro-simulations. The micro-simulations replicated virus transmission scenarios in which virus-carrying students were present in the actual contact history. The results showed that a significant amount of virus adhered to the items predicted to be fomites. Interestingly, the micro-simulations indicated that most viral copies were transmitted through single items. The analysis of contact history, contact networks, and micro-simulations relies on video-recorded behavioral data, highlighting the importance of this method. This study contributes significantly to the prevention of infectious diseases in elementary schools by providing evidence-based information about transmission pathways and behavior-related risks.

Effects of Spoken Phones and Patient Characteristics on Respiratory Aerosol Emission

OBJECTIVES

This study investigates how the production of three different phones ([a], [o], [r]), as well as breathing, coughing, and individual characteristics, influences respiratory particle emission.

DESIGN

Experimental study.

METHODS

Particle size distribution and sound pressure levels (SPL) were measured in 41 infection-free participants under controlled conditions. The measurement instruments, condensation particle counter (3775, TSI Inc.), and aerodynamic particle sizer (APS 3321, TSI Inc.), covered the size range of 0.004-10 µm. Exhaled flow rates were calculated from CO2 concentrations measured with LI-840A NDIR gas analyzer (LI-COR Environmental).

RESULTS

Production of [o] generated more particles than production of [a] across all size fractions. The alveolar trill [r] generated more small particles than did the vowels. SPL had a consistent positive effect on particle generation but did not fully explain the differences. Exhaled flow rates showed no statistical differences between the phones. Higher age was associated with elevated particle emission in breathing. Higher exhaled flow rate and higher body mass index (BMI) were associated with higher particle emission in coughing. No systematic connection between peak expiratory flow (PEF) or sex and particle emission was observed.

CONCLUSIONS

Understanding respiratory aerosol generation, in different situations and individuals, is critical for advancing knowledge of airborne transmission of diseases. Our findings corroborate prior evidence of an association between SPL and particle emission in voiced activities. Particle production also varies systematically across different phones, irrespective of SPL. The predominance of small particles in the phonation of [r] suggests the production of satellite particles from the tongue vibration. The higher particle generation in the phonation of [o] compared with [a] suggests the oral opening may contribute to the number of emitted particles. None of the individual characteristics-age, sex, BMI, or PEF-was a systematic predictor of particle production across all respiratory activities.

Antiviral and Immune Enhancement Effect of Platycodon grandiflorus in Viral Diseases: A Potential Broad-Spectrum Antiviral Drug

BACKGROUND

Traditional Chinese medicine offers potential therapeutic options for viral infections. Platycodon grandiflorus (PG) is a perennial herb known for its efficacy in treating respiratory infections, including asthma, cough, and bronchitis, making it a key focus in antiviral drug research. The purpose of the study is to provide a basis for functional studies on PG and generate new insights for treating viral diseases.

METHODS

Research articles from 1990 to 2024 related to PG and viruses were obtained from databases, such as PubMed, Web of Science, and Science Direct, and systematically analysed.

RESULTS

PG demonstrates inhibitory effects on viruses such as severe acute respiratory syndrome coronavirus and porcine reproductive and respiratory syndrome virus by blocking various stages of viral proliferation or activating the host immune system. It also reduces inflammation through NF-κB, PI3K/AKT, MAPK, and other signalling pathways, enhancing T cell and macrophage function and increasing host immunity. PG exhibits diverse pharmacological effects with promising clinical applications for antiviral and immune modulation. Given its medicinal significance, PG holds substantial potential for further exploration and development.

CONCLUSION

PG, due to its antiviral, anti-inflammatory, and immune-boosting properties, can be used as an antiviral drug.

Bioaerosol Characterization with Vibrational Spectroscopy: Overcoming Fluorescence with Photothermal Infrared (PTIR) Spectroscopy

Aerosols containing biological material (i.e., bioaerosols) impact public health by transporting toxins, allergens, and diseases and impact the climate by nucleating ice crystals and cloud droplets. Single particle characterization of primary biological aerosol particles (PBAPs) is essential, as individual particle physicochemical properties determine their impacts. Vibrational spectroscopies, such as infrared (IR) or Raman spectroscopy, provide detailed information about the biological components within atmospheric aerosols but these techniques have traditionally been limited due to the diffraction limit of IR radiation (particles >10 μm) and fluorescence of bioaerosol components overwhelming the Raman signal. Herein, we use photothermal infrared spectroscopy (PTIR) to overcome these limitations and characterize individual PBAPs down to 0.18 μm. Both optical-PTIR (O-PTIR) and atomic force microscopy-PTIR (AFM-PTIR) were used to characterize bioaerosol particles generated from a cyanobacterial harmful algal bloom (cHAB) dominated by Planktothrix agardhii. PTIR spectra contained modes consistent with traditional Fourier transform infrared (FTIR) spectra for biological species, including amide I (1630-1700 cm-1) and amide II (1530-1560 cm-1). The fractions of particles containing biological materials were greater in supermicron particles (1.8-3.2 μm) than in submicron particles (0.18-0.32 and 0.56-1.0 μm) for aerosolized cHAB water. These results demonstrate the potential of both O-PTIR and AFM-PTIR for studying a range of bioaerosols with vibrational spectroscopy.

Severity and risk to inhalation of pathogen-laden aerosol in large public spaces: Insights from fangcang shelter hospitals under multi-location release

The key to strengthening the inherent safety of large public spaces and implementing precise preventive measures lies in clarifying the transmission risks of respiratory infectious diseases based on multiple factors. This work innovatively improves a pathogen inhalation infection risk prediction model and attempts to apply it to a Fangcang Shelter Hospital to investigate the effect of pathogen release location on risk distribution and the role of airflow distribution in risk control mechanisms. The model used in the study improved in resolution and accuracy, shedding light on the airflow distribution mechanisms involved in pathogen transport and risk control, thus providing a quantitatively realistic landscape of the spread of respiratory infectious diseases in large indoor environments. Predictions reveal a significant unevenness in the spatial distribution of infection probabilities within the multi-patient shelter unit, which is further exacerbated by different release locations, and that extreme infection risks can reach 4 to 14 times the average. Additionally, the study noted that the infection probability in the medical staff area due to the long-distance transmission of contaminants can reach as high as 1.72 % and that patients from ward 6# could potentially infect a healthcare worker every four days.

Ultralight Electrospun Composite Filters with Vertical Ternary Spatial Network for High-Performance PM0.3 Purification

Air pollutants, particularly highly permeable particulate matter (PM), threaten public health and environmental sustainability due to extensive filter media consumption. Existing melt-blown nonwoven filters struggle with PM0.3 removal, energy consumption, and disposal burdens. Here, an ultralight composite filter with a vertical ternary spatial network (TSN) structure that saves ≈98% of raw material usage and reduces fabrication time by 99.4%, while simultaneously achieving high-efficiency PM0.3 removal (≥99.92%), eco-friendly regeneration (near-zero energy consumption), and enhanced wearing comfort (breathability >80 mm s⁻¹, infrared transmittance >85%), is reported. The TSN filter consists of a hybrid layer of microspheres (average diameter ≈1 µm)/superfine nanofibers (≈20 nm) sandwiched between two nanofiber scaffolds (diameter ≈400 nm and ≈100 nm). This arrangement offers high porosity (≈85%), ultralow areal density (<1 g m-2), alow airflow resistance (<90 Pa), guaranteeing superb thermal comfort. Notably, utilizing scalable one-step free surface electrospinning technology, TSN mats can be mass-produced at a rate of 60 meters per hour (width of 1.6 meters), which is critical and verified for various applications including window screens, individual respiratory protectors, and dust collectors. This work provides a viable strategy for designing high-performance nanofiber filter media through structural regulation in a scalable, cost-effective, and sustainable way.