Analysis of Compounding and Broadband Extinction Properties of Novel Bioaerosols

Artificially prepared microbial spores have excellent electromagnetic attenuation properties due to their special composition and structure. At present, studies on the optical properties of microbial spores have mainly focused on those with a single band or a single germplasm, which has limitations and cannot reveal the optical properties comprehensively. In this paper, 3 kinds of laboratory-prepared microbial spores were selected for compounding, and the spectral reflectivities of single-germplasm biospores and compound biospores were measured in the wavebands of 0.25–2.4 and 3–15 μm. The complex refractive indices (CRIs) were calculated in combination with the Kramers–Kronig (K-K) algorithm. Relying on the smoke box broadband test system, the transmittance of single-germplasm bioaerosols and compound bioaerosols from the ultraviolet (UV) band to the far-infrared (FIR) band was measured, and the mass extinction coefficients were calculated. The results indicate that the trend of the complex refractive indices of the compound spores is consistent with that of the single-germplasm spores with a larger particle size. For the single-germplasm bioaerosols, the lowest transmittance values were 2.21, 5.70 and 6.27% in the visible (VIS), near-infrared (NIR) and middle-infrared (FIR) bands, and the mass extinction coefficients reached 1.15, 0.87 and 0.84 m2/g, respectively. When AO and BB spores were compounded at 4:1, the extinction performance of the bioaerosols somewhat improved in all wavebands. These results can help to comprehensively analyze the optical properties of bioaerosols and provide ideas for the development of new extinction materials.

COVID-style gene surveillance to fight wheat fungus

See PDF] First reported in Brazil in 1985, wheat blast disease spreads through infected seeds, crop residues and spores that can travel long distances in the air. "Wheat is a staple food for 35 per cent of the world's population, so a disease that threatens pandemic potential could cause serious food security implications,” she told SciDev.Net. "Thanks to the prompt and public release of genomic data by the international scientific community through the OpenWheatBlast initiative, we were able to detect, track, and characterise the fungal lineage responsible for recent wheat blast outbreaks,” said lead author Sergio Latorre Ochoa from University College London.

Does sending honey bee, Apis mellifera (Hymenoptera: Apidae), colonies to lowbush blueberry, Vaccinium angustifolium (Ericaceae), for pollination increase Nosema spp. (Nosematidae) spore loads?

In the Canadian Maritimes, many beekeepers rent honey bee, Apis mellifera Linnaeus (Hymenoptera: Apidae), hives to growers of lowbush blueberry, Vaccinium angustifolium (Ericaceae), for pollination services. Anecdotally, hives have less vigour following pollination, potentially due to higher Nosema spp. (Nosematidae) spore loads, the microsporidian causing nosemosis. We undertook a study to determine whether sending honey bee hives to lowbush blueberry fields for pollination (blueberry hives) results in higher Nosema spp. spore loads relative to hives remaining in apiaries (home hives). Nosema spp. spore loads were quantified using light microscopy. Nosema apis and Nosema ceranae were differentiated using polymerase chain reaction and sequencing. Nosema spp. spore loads were greatest in April and May and declined to low levels from June to September. Ninety-eight per cent of Nosema detections were positive for N. ceranae. In April, blueberry hives had a lower spore load than home hives did;however, in June, spore loads were significantly higher in blueberry hives. No other differences in Nosema spp. spore loads were observed between hive types. We conclude that Nosema ceranae is the dominant Nosema species in the Canadian Maritimes and that using hives for lowbush blueberry pollination does not appear to influence long-term Nosema spp. spore loads.

Cow dung fires linked to black fungus epidemic in India

Mucormycosis, a dangerous infection caused by Mucorales fungi, has an overall mortality rate of 54 per cent, according to the US Centers for Disease Control and Prevention. Jessy Skaria, an author of the paper and an independent researcher from Houston, Texas, tells SciDev.Net that the unusually high incidence of COVID-19- associated mucormycosis in India was attributed by most physicians and researchers to a combination of SARS-Cov-2 viral infection with diabetes and treatment using steroids. “To establish the role of herbivore dung in the causation of COVID-19-associated mucormycosis, case control studies, genetic (phylogenetic) studies and other aerosol viability analysis of Mucorales spores, post-burning, is critical,” Rodney Rohde, chair and professor of clinical laboratory science at Texas State University, tells SciDev.Net.

Application of an Ultrasonic Nebulizer Closet in the Disinfection of Textiles and Footwear.

The emergence of the coronavirus disease 2019 (COVID-19) pandemic highlighted the importance of disinfection processes in health safety. Textiles and footwear have been identified as vectors for spreading infections. Therefore, their disinfection can be crucial to controlling pathogens' dissemination. The present work aimed to evaluate the effectiveness of a commercial disinfectant aerosolized by an ultrasonic nebulizer closet as an effective method for disinfecting textiles and footwear. The disinfection was evaluated in three steps: suspension tests; nebulization in a 0.08 m3 closet; nebulization in the upscaled 0.58 m3 closet. The disinfection process of textiles and footwear was followed by the use of bacteriophages, bacterial spores, and bacterial cells. The disinfection in the 0.58 m3 closet was efficient for textiles (4 log reduction) when bacteriophage Lambda, Pseudomonas aeruginosa, and Bacillus subtilis were used. The footwear disinfection was achieved (4 log reduction) in the 0.08 m3 closet for Escherichia coli and Staphylococcus aureus. Disinfection in an ultrasonic nebulization closet has advantages such as being quick, not wetting, being efficient on porous surfaces, and is performed at room temperature. Ultrasonic nebulization disinfection in a closet proves to be useful in clothing and footwear stores to prevent pathogen transmission by the items' widespread handling.

Effective inactivation of Bacillus atrophaeus spores and Escherichia coli on disposable face masks using ultraviolet laser irradiation.

Due to the widespread emergence of COVID-19, face masks have become a common tool for reducing transmission risk between people, increasing the need for sterilization methods against mask-contaminated microorganisms. In this study, we measured the efficacy of ultraviolet (UV) laser irradiation (266 nm) as a sterilization technique against Bacillus atrophaeus spores and Escherichia coli on three different types of face mask. The UV laser source demonstrated high penetration of inner mask layers, inactivating microorganisms in a short time while maintaining the particle filtration efficiency of the masks. This study demonstrates that UV laser irradiation is an efficient sterilization method for removing pathogens from face masks.

Recent developments in the use of cold plasma, high hydrostatic pressure, and pulsed electric fields on microorganisms and viruses in seafood.

Non-thermal processing methods, such as cold plasma (CP), high pressure processing (HPP) and pulsed electric fields (PEF), have been proposed for natural and fresh-like foods to inactivate microorganisms at nearly-ambient or moderate temperature. Since natural, safe, and healthy foods with longer shelf-life are increasingly demanded, these requests are challenging to fulfill by using current thermal processing technologies. Thus, novel preservation technologies based on non-thermal processing methods are required. The aim of this article is to provide recent developments in maintaining seafood safety via CP, HHP, and PEF technologies, as well as their mechanisms of action regarding contamination with food-borne microorganisms. Their application to control parasites, spores and the possibility to eradicate the hazard of SARS-CoV-2 transmission through seafood products are also discussed. CP, HHP, and PEF have been applied to inactivate food-borne microorganisms in the seafood industry. However, the drawbacks for each emerging technology have also been reported. To ensure safety and maintain quality of seafood products, the combination of these processing techniques with natural antimicrobial agents or existing thermal methods may be more applicable in the case of the seafood industry. Further studies are required to examine the effects of these methods on viruses, parasites, and SARS-CoV-2 in seafood.

Viruses Such as SARS-CoV-2 Can Be Partially Shielded from UV Radiation When in Particles Generated by Sneezing or Coughing: Numerical Simulations

UV radiation can inactivate viruses such as SARS-CoV-2. However, designing effective UV germicidal ir- radiation (UVGI) systems can be difficult because the effects of dried respiratory droplets and other fomites on UV light intensities are poorly understood. Numerical modeling of UV intensities inside virus- containing particles on surfaces can increase understanding of these possible reductions in UV intensity. We model UV intensities within spherical approximations of virions randomly positioned within spherical particles. The model virions and dried particles have sizes and optical properties to approximate SARS- CoV-2 and dried particles formed from respiratory droplets, respectively. In 1-, 5- and 9-m diameter par- ticles on a surface, illuminated by 260-nm UV light from a direction perpendicular to the surface, 0 , 10 and 18 (respectively) of simulated virions are exposed to intensities less than 1/100 th of intensities in individually exposed virions (i.e., they are partially shielded). Even for 302-nm light (simulating sunlight), where absorption is small, 0 and 11 of virions in 1- and 9-m particles have exposures 1/100 th those of individually exposed virions. Shielding is small to negligible in sub-micron particles. Results show that shielding of virions in a particle can be reduced by illuminating a particle either from multiple widely separated incident directions, or by illuminating a particle rotating in air for a time sufficient to rotate through enough orientations. Because highly UV-reflective paints and surfaces can increase the angular ranges of illumination and the intensities within particles, they appear likely to be useful for reducing shielding of virions embedded within particles.

Invasive Mucormycosis - An Enigma.

Mucormycosis is an emerging infection in the present post-COVID-19 era, associated with high morbidity and mortality. We are reporting an interesting case of invasive rhino-orbital-cerebral mucormycosis in a 65-year-old female who presented with left nasal and orbital swelling after COVID-19 infection associated with uncontrolled diabetes mellitus. Histopathological and microbiology examination favored mucormycosis. Finally, endoscopic debridement of the lesion was done with left orbital exenteration. The patient at present is clinically stable. As these cases have been seen in many suspected and confirmed COVID-19 cases, early diagnosis and treatment will salvage the patient.

Competing Bioaerosols May Influence the Seasonality of Influenza-Like Illnesses, including COVID-19. The Chicago Experience.

Data from Chicago confirm the end of flu season coincides with the beginning of pollen season. More importantly, the end of flu season also coincides with onset of seasonal aerosolization of mold spores. Overall, the data suggest bioaerosols, especially mold spores, compete with viruses for a shared receptor, with the periodicity of influenza-like illnesses, including COVID-19, a consequence of seasonal factors that influence aerosolization of competing species.

Development of a highly effective low-cost vaporized hydrogen peroxide-based method for disinfection of personal protective equipment for their selective reuse during pandemics.

BACKGROUND: Personal Protective Equipment (PPE) is required to safely work with biological agents of bacterial (i.e. Mycobacterium tuberculosis) or viral origin (Ebola and SARS). COVID-19 pandemic especially has created unforeseen public health challenges including a global shortage of PPE needed for the safety of health care workers (HCWs). Although sufficient stocks of PPE are currently available, their critical shortage may develop soon due to increase in demand and depletion of existing supply lines. To empower our HCWs and ensure their continued protection, proactive measures are urgently required to develop procedures to safely decontaminate the PPEs to allow their "selective reuse" during contingency situations. METHODS: Herein, we have successfully developed a decontamination method based on vaporized hydrogen peroxide (VHP). We have used a range of concentration of hydrogen peroxide to disinfect PPE (coveralls, face-shields, and N-95 masks). To ensure a proper disinfection, we have evaluated three biological indicators namely Escherichia coli, Mycobacterium smegmatis and spores of Bacillus stearothermophilus, considered as the gold standard for disinfection processes. We next evaluated the impact of repeated VHP treatment on physical features, permeability, and fabric integrity of coveralls and N-95 masks. Next, we performed Scanning Electron Microscopy (SEM) to evaluate microscopic changes in fiber thickness of N-95 masks, melt blown layer or coverall body suits. Considering the fact that any disinfection procedure should be able to meet local requirements, our study included various regionally procured N-95 masks and coveralls available at our institute All India Institute of Medical Sciences (AIIMS), New Delhi, India. Lastly, the practical utility of VHP method developed herein was ascertained by operationalizing a dedicated research facility disinfecting used PPE during COVID-19. RESULTS: Our prototype studies show that a single VHP cycle (7-8% Hydrogen peroxide) could disinfect PPE and PPE housing room of about 1200 cubic feet (length10 ft × breadth 10 ft × height 12 ft) in less than 10 min, as noted by a complete loss of B. stearothermophilus spore revival. The results are consistent and reproducible as tested in over 10 cycles in our settings. Further, repeated VHP treatment did not result in any physical tear, deformity or other appreciable change in the coverall and N-95 masks. Our permeation tests evaluating droplet penetration did not reveal any change in permeability post-VHP treatments. Also, SEM analysis indeed revealed no significant change in fiber thickness or damage to fibers of coveralls or melt blown layer of N-95 masks essential for filtration. There was no change in user comfort and experience following VHP treatment of PPE. Based on results of these studies, and parameters developed and optimized, an institutional research facility to disinfect COVID-19 PPE is successfully established and operationalized with more than 80% recovery rate for used PPE post-disinfection. CONCLUSIONS: Our study, therefore, successfully establishes the utility of VHP to effectively disinfect PPE for a possible reuse as per the requirements. VHP treatment did not damage coveralls, cause physical deformity and also did not alter fabric architecture of melt blown layer. We observed that disinfection process was successful consistently and therefore believe that the VHP-based decontamination model will have a universal applicability and utility. This process can be easily and economically scaled up and can be instrumental in easing global PPE shortages in any biosafety facility or in health care settings during pandemic situation such as COVID-19.