Practical Indicators for Risk of Airborne Transmission in Shared Indoor Environments and Their Application to COVID-19 Outbreaks.

Some infectious diseases, including COVID-19, can undergo airborne transmission. This may happen at close proximity, but as time indoors increases, infections can occur in shared room air despite distancing. We propose two indicators of infection risk for this situation, that is, relative risk parameter (Hr) and risk parameter (H). They combine the key factors that control airborne disease transmission indoors: virus-containing aerosol generation rate, breathing flow rate, masking and its quality, ventilation and aerosol-removal rates, number of occupants, and duration of exposure. COVID-19 outbreaks show a clear trend that is consistent with airborne infection and enable recommendations to minimize transmission risk. Transmission in typical prepandemic indoor spaces is highly sensitive to mitigation efforts. Previous outbreaks of measles, influenza, and tuberculosis were also assessed. Measles outbreaks occur at much lower risk parameter values than COVID-19, while tuberculosis outbreaks are observed at higher risk parameter values. Because both diseases are accepted as airborne, the fact that COVID-19 is less contagious than measles does not rule out airborne transmission. It is important that future outbreak reports include information on masking, ventilation and aerosol-removal rates, number of occupants, and duration of exposure, to investigate airborne transmission.

[The mechanism of hyperbaric oxygen regulating HMGB1 in the prevention and treatment of encephalopathy after acute CO poisoning].

Objective: To study the expression of high mobility group protein 1 (HMGB1) in the brain of rats after hyperbaric oxygen (HBO) treatment of acute carbon monoxide poisoning (DEACMP) , and to explore the mechanism of HBO in the prevention and treatment of DEACMP pathological process by regulating HMGB1. Methods: 108 SD rats were randomly divided into control group (NC group) and co group (CO group) . HBO treatment group (HBO group) , 48 rats in each group. Co group and HBO group were used to establish CO poisoning model, HBO group were treated with hyperbaric oxygen once a day. Water maze test was used to detect and analyze the memory retention ability of three groups of rats in 3 d, 7 d, 14 d. ELISA was used to detect the plasma concentration of HMGB1、IL-6、TNF-α in three groups of rats on the 1 d, 3 d, 7 d, 14 d, 21 d Concentration. Western blotting was used to detect the expression of HMGB1 and Caspase-3 in the brain of the three groups on the 1 d, 3 d, 7 d, 14 d, 21 d. TUNEL staining was used to detect the apoptosis of hippocampal neurons in the three groups. Results: Compared with NC group, the average escape latency of rats in CO group and HBO group was significantly prolonged, and the activity time of platform quadrant in CO group was significantly shortened on 14 d and 21 d (P<0.05) ; compared with CO group, the average escape latency of HBO group on 7 d, 14 d and 21 d was significantly shortened (P<0.05) . Compared with NC group, plasma HMGB1 in CO group and HBO group were significantly increased (P<0.05) ; after 3 days, HBO group was significantly lower than co group, the difference was statistically significant (P<0.05) . The levels of IL-6 and TNF-α in HBO group and co group increased rapidly and then decreased gradually. The increased levels of IL-6 and TNF-α in HBO group were significantly lower than those in CO group (P<0.05) . Compared with NC group, the expression of HMGB1 and Caspase-3 in CO group was significantly increased on 3 d, 7 d and 14 d (P<0.05) ; the expression of HMGB1 and Caspase-3 in HBO group was significantly increased on 3 d, 7 d, 14 d and 21 d (P<0.05) ; compared with CO group, the expression of HMGB1 and Caspase-3 in HBO group decreased significantly on 3 d, 7 d, 14 d and 21 d (P<0.05) . The apoptotic index of nerve cells in CO group began to increase at 3 days, which was significantly different from that of NC group (P<0.05) , and the difference was still statistically significant on 21 d (P<0.05) ; the apoptotic index of nerve cells in HBO group was slightly increased, but there was no significant difference compared with NC group (P>0.05) , and the apoptotic index of 3 d, 7 d, 14 d and 21 d in HBO group was significantly lower than that in CO group (P<0.05) . Conclusion: acute CO poisoning can induce the release of HMGB1 and a variety of inflammatory factors. HMGB1 can promote the apoptosis of nerve cells after acute CO poisoning by up regulating the expression of caspase-3 protein, and participate in the pathological process of DEACMP. HBO can down regulate the expression of HMGB1, IL-6, TNF-α and caspase-3 protein, inhibit the apoptosis of nerve cells, and play a protective role on nerve cells.

Transmission routes of influenza A(H1N1)pdm09: analyses of inflight outbreaks.

Knowledge about the infection transmission routes is significant for developing effective intervention strategies. We searched the PubMed databases and identified 10 studies with 14 possible inflight influenza A(H1N1)pdm09 outbreaks. Considering the different mechanisms of the large-droplet and airborne routes, a meta-analysis of the outbreak data was carried out to study the difference in attack rates for passengers within and beyond two rows of the index case(s). We also explored the relationship between the attack rates and the flight duration and/or total infectivity of the index case(s). The risk ratios for passengers seated within and beyond the two rows of the index cases were 1.7 (95% confidence interval (CI) 0.98-2.84) for syndromic secondary cases and 4.3 (95% CI 1.25-14.54) for laboratory-confirmed secondary cases. Furthermore, with an increase of the product of the flight duration and the total infectivity of the index cases, the overall attack rate increased linearly. The study indicates that influenza A(H1N1)pdm09 may mainly be transmitted via the airborne route during air travel. A standardised approach for the reporting of such inflight outbreak investigations would help to provide more convincing evidence for such inflight transmission events.

Probable transmission routes of the influenza virus in a nosocomial outbreak.

Influenza is a long-standing public health concern, but its transmission remains poorly understood. To have a better knowledge of influenza transmission, we carried out a detailed modelling investigation in a nosocomial influenza outbreak in Hong Kong. We identified three hypothesised transmission modes between index patient and other inpatients based on the long-range airborne and fomite routes. We considered three kinds of healthcare workers' routine round pathways in 1140 scenarios with various values of important parameters. In each scenario, we used a multi-agent modelling framework to estimate the infection risk for each hypothesis and conducted least-squares fitting to evaluate the hypotheses by comparing the distribution of the infection risk with that of the attack rates. Amongst the hypotheses tested in the 1140 scenarios, the prediction of modes involving the long-range airborne route fit better with the attack rates, and that of the two-route transmission mode had the best fit, with the long-range airborne route contributing about 94% and the fomite route contributing 6% to the infections. Under the assumed conditions, the influenza virus was likely to have spread via a combined long-range airborne and fomite routes, with the former predominant and the latter negligible.

Association of liver X receptor α (LXRα) gene polymorphism and ischemic stroke.

We examined the relationship between the liver X receptor a gene (LXRα) rsl2221497 polymorphism and the susceptibility to ischemic stroke in a Chinese population. The polymerase chain reaction-restriction fragment length polymorphism technique was used to detect the genotype of rsl2221497 in the LXRαgene of 300 stroke patients and 300 healthy control subjects. The chi-square test was used to analyze the genotype distribution between the 2 groups. We found that the risk of stroke in carriers with the AA + GA genotype was 2.12-fold higher than that in GG genotype carriers (odds ratio = 2.12, 95% confidence interval: 1.58-2.99, P < 0.05). The risk of stroke in carriers of the A allele increased by 1.03-fold compared to that in G allele carriers (odds ratio = 2.03, 95% confidence interval: 1.44-3.01, P < 0.01). After adjusting for other confounding factors such smoking, hypertension, and diabetes, the A allele was found to be an independent risk factor for stroke. Therefore, the rsl2221497 polymorphism in the LXRαgene was associated with the susceptibility to stroke in a Chinese population.

Molecular analysis of intestinal bacterial microbiota of broiler chickens fed diets containing fermented cottonseed meal.

The study was conducted to investigate the effects of dietary inclusion of fermented cottonseed meal (FCM) on the ileal and cecal bacterial microbiota of broiler chickens. A total of 300 newborn yellow-feathered broiler chickens were randomly divided into 2 treatments with 3 replicates each (50 birds per replicate): control and 80 g/kg of FCM group. The feeding trial lasted for 42 d. Ileal and cecal digesta samples were collected from 8 chicks per replicate at 21 and 42 d of age to determine the composition of bacterial microbiota using denaturing gradient gel electrophoresis, cloning, sequencing, and real-time quantitative PCR analysis. The results demonstrated that the microbial composition in the ileum and cecum were considerably affected by the diet. The similarity dendrogram of banding profiles showed a more rapid stabilization of intestinal bacterial microbiota in broilers fed diets supplemented with FCM, compared with that of the birds fed the control diet. No significant difference was observed in total number of bands and Shannon-Weaver index, indicating that FCM had no effects on bacterial diversity. However, enumeration of bacteria in the ileal and cecal contents by quantitative PCR showed an increased (P < 0.05) population of lactobacilli, as well as a decreased (P < 0.05) Escherichia coli number by the dietary inclusion of FCM. In summary, dietary inclusion of FCM did not affect the intestinal microbial diversity but shifted intestinal microbiota, with a more homogenous population and an increased colonization of lactobacilli. The results also support the concept that dietary FCM inclusion could promote the beneficial bacteria in the intestinal tract.

Impact of introducing consultant resident on-call in a district general hospital.

Introduction of structured competency-based training for specialty registrars and implementation of European Working Time Directives (EWTD) have affected the quality of maternity care. In York District Hospital, consultant resident on-call (CRO) without registrar cover was introduced in July 2010 to address the long-standing problem of middle-grade out-of-hours coverage. To examine the impact of introducing out-of-hours consultant resident on-call on maternity care, data from 486 deliveries including 59 CRO and 59 registrar shifts were collected retrospectively, from July 2010 to April 2011. Main outcome measures include mode of delivery, second-stage management, maternal and neonatal outcomes. Feedback from consultants, junior trainees and midwives on the impact of CRO were collated through semi-structured interviews. More normal vaginal deliveries (71.8% vs 63.0%) and fewer emergency caesarean sections (12.5% vs 20.6%) were performed in the CRO shifts compared with registrar on-call. Instrumental delivery rates in labour rooms vs theatre were higher when compared with the registrar group. Overall, good patient and staff experience was reflected during interviews. Our work shows that introduction of CRO in out-of-hours settings is acceptable among staff and is associated with fewer obstetric interventions. However, improved job descriptions may be needed in order to make the CRO post more attractive.

Effects of Replacement of Soybean Meal by Fermented Cottonseed Meal on Growth Performance, Serum Biochemical Parameters and Immune Function of Yellow-feathered Broilers.

The study was conducted to examine the effects of partially replacing soybean meal (SBM) by solid-state fermented cottonseed meal (FCSM) on growth performance, serum biochemical parameters and immune function of broilers. After inoculated with Bacillus subtilis BJ-1 for 48 h, the content of free gossypol in cottonseed meal was decreased from 0.82 to 0.21 g/kg. A total of 600, day-old male yellow-feathered broilers were randomly divided into four groups with three replicates of 50 chicks each. A corn-SBM based control diet was formulated and the experimental diets included 4, 8 or 12% FCSM, replacing SBM. Throughout the experiment, broilers fed 8% FCSM had higher (p<0.05) body weight gain than those fed 0, 4 and 12% FCSM. The feed intake in 8% FCSM group was superior (p<0.05) to other treatments from d 21 to 42. On d 21, the concentration of serum immunoglobin M in the 4% and 8% FCSM groups, as well as the content of complements (C3, C4) in 8% FCSM group were greater (p<0.05) than those in the SBM group. Besides, birds fed 8% FCSM had increased (p<0.05) serum immunoglobin M, immunoglobulin G and complement C4 levels on d 42 compared with bird fed control diet. No differences (p>0.05) were found between treatments regarding the serum biochemical parameters and the relative weights of immune organs. In conclusion, FCSM can be used in broiler diets at up to 12% of the total diet and an appropriate replacement of SBM with FCSM may improve growth performance and immunity in broilers.

Correlations between clinical illness, respiratory virus infections and climate factors in a tropical paediatric population.

Weekly (August 2003-December 2008) numbers of five common paediatric diseases and the incidence of respiratory viruses were obtained from a children's hospital in Singapore and correlated with climate data using multivariate time-series techniques. Upper respiratory tract infections were positively correlated with the incidences of influenza A, B, respiratory syncytial virus (RSV) and parainfluenza viruses (types 1-3 combined). Lower respiratory tract infections were positively correlated with only the incidence of RSV. Both upper and lower respiratory tract infections were negatively correlated with relative humidity. Asthma admissions were negatively correlated with maximum temperature and positively correlated with the incidence of influenza B and increasing hours of sunshine. Although sporadic cases of adenovirus infection were identified, not enough cases were available for a more detailed analysis. Gastroenteritis and urinary tract infections, included as control diseases, were not correlated significantly with any climate parameters. These correlations are compatible with current understanding of respiratory virus survival under certain climate conditions and may assist the prediction of disease burdens and hospital resource planning in such tropical environments.

Missed diagnosis of influenza B virus due to nucleoprotein sequence mutations, Singapore, April 2011.

A new influenza B variant was discovered in Singapore in April 2011 during diagnostic testing of a 3-year-old boy with respiratory symptoms. Influenza B virus was isolated from culture and confirmed by standard immunofluorescence testing, but was not detected by the routine, in-house influenza screening reverse-transcription polymerase chain reaction assay that targets the nucleoprotein (NP) gene. Subsequent sequencing investigations demonstrated that several other published assays targeting NP could also fail to detect this novel variant.

Dismantling myths on the airborne transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

The coronavirus disease 2019 (COVID-19) pandemic has caused untold disruption throughout the world. Understanding the mechanisms for transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is key to preventing further spread, but there is confusion over the meaning of 'airborne' whenever transmission is discussed. Scientific ambivalence originates from evidence published many years ago which has generated mythological beliefs that obscure current thinking. This article collates and explores some of the most commonly held dogmas on airborne transmission in order to stimulate revision of the science in the light of current evidence. Six 'myths' are presented, explained and ultimately refuted on the basis of recently published papers and expert opinion from previous work related to similar viruses. There is little doubt that SARS-CoV-2 is transmitted via a range of airborne particle sizes subject to all the usual ventilation parameters and human behaviour. Experts from specialties encompassing aerosol studies, ventilation, engineering, physics, virology and clinical medicine have joined together to produce this review to consolidate the evidence for airborne transmission mechanisms, and offer justification for modern strategies for prevention and control of COVID-19 in health care and the community.

Incidence of common respiratory viral infections related to climate factors in hospitalized children in Hong Kong.

Hong Kong has a subtropical climate and an influenza seasonality lying approximately mid-way (March-June) between those of the Northern (November-March) and Southern (June-September) hemispheres. Respiratory syncytial virus (RSV) shares a similar seasonality to that of influenza in Hong Kong and is another important respiratory infection of childhood. Daily virus incidence data from public hospitals in Hong Kong's New Territory East Cluster, together with Hong Kong climate data were obtained for 2000-2007. Statistical time-series analysis using monthly time windows showed that influenza A and RSV incidence increased with higher environmental relative humidity, whereas influenza B incidence decreased with higher environmental temperatures. The other climate variables (including vapour pressure as a measure of absolute humidity) were not significantly related to the incidence of these respiratory viruses. Data from this study further reinforces the concept that the relationship between climate factors and respiratory virus incidence differ between subtropical/tropical and temperate countries.

Inferring super-spreading from transmission clusters of COVID-19 in Hong Kong, Japan, and Singapore.

Super-spreading events in an outbreak can change the nature of an epidemic. Therefore, it is useful for public health teams to determine whether an ongoing outbreak has any contribution from such events, which may be amenable to interventions. We estimated the basic reproductive number (R0) and the dispersion factor (k) from empirical data on clusters of epidemiologically linked coronavirus disease 2019 (COVID-19) cases in Hong Kong, Japan and Singapore. This allowed us to infer the presence or absence of super-spreading events during the early phase of these outbreaks. The relatively large values of k implied that large cluster sizes, compatible with super-spreading, were unlikely.

Chemistry and long-term decomposition of roots of Douglas-fir grown under elevated atmospheric carbon dioxide and warming conditions.

Elevated atmospheric CO(2) concentrations and warming may affect the quality of litters of forest plants and their subsequent decomposition in ecosystems, thereby potentially affecting the global carbon cycle. However, few data on root tissues are available to test this feedback to the atmosphere. In this study, we used fine (diameter < or = 2 mm) and small (2-10 mm) roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings that were grown for 4 yr in a 2 x 2 factorial experiment: ambient or elevated (+ 180 ppm) atmospheric CO(2) concentrations, and ambient or elevated (+3.8 degrees C) atmospheric temperature. Exposure to elevated CO(2) significantly increased water-soluble extractives concentration (%WSE), but had little effect on the concentration of N, cellulose, and lignin of roots. Elevated temperature had no effect on substrate quality except for increasing %WSE and decreasing the %lignin content of fine roots. No significant interaction was found between CO(2) and temperature treatments on substrate quality, except for %WSE of the fine roots. Short-term (< or = 9 mo) root decomposition in the field indicated that the roots from the ambient CO(2) and ambient temperature treatment had the slowest rate. However, over a longer period of incubation (9-36 mo) the influence of initial substrate quality on root decomposition diminished. Instead, the location of the field incubation sites exhibited significant control on decomposition. Roots at the warmer, low elevation site decomposed significantly faster than the ones at the cooler, high elevation site. This study indicates that short-term decomposition and long-term responses are not similar. It also suggests that increasing atmospheric CO(2) had little effect on the carbon storage of Douglas-fir old-growth forests of the Pacific Northwest.

Evaluating the aptima HIV-1 quant Dx, HCV quant Dx and HBV quant assays against the Abbott HIV-1, HCV and HBV RealTime assays.

BACKGROUND: Viral load measurement is routine for the management of patients infected with HIV, HCV or HBV, using sensitive, quantitative, nucleic acid amplification tests (NAATs). However, platforms are not equivalent in terms of turnaround time, random access capability and operator hands-on time. OBJECTIVES AND STUDY DESIGN: We compared the performance of the Hologic Panther transcription-mediated amplification based Aptima assays for HIV, HBV and HCV viral load measurement with the corresponding Abbott m2000 RealTime assays. All Aptima assays were run according to the manufacturer's instructions, on archived patient samples for HIV (n = 251 including subtypes 01_AE, A (A1), B, BG recombinant, C CRF02_AG and G), HBV (n = 117 including genotypes A, B, C and D) and HCV (n = 82 including genotypes 1, 2, 3 and 4). Additional testing was performed with WHO international standards and expanded HIV-1 subtype and HCV NIBSC genotype panels. RESULTS: The Hologic Panther Aptima assays for HIV-1 RNA, HBV DNA and HCV RNA viral load measurements performed equivalently to the Abbott m2000 RealTime assays. The performance of the Aptima assays was also acceptable on the WHO and NIBSC standards and subtype/genotype panels. CONCLUSIONS: The Aptima Panther platform offers equivalent clinical performance for the viral load measurement of these three viruses, with the added benefits of reduced turnaround time, random access capability and reduced 'hands-on time' for staff, resulting in a potentially superior workflow for diagnostic laboratories.

Hypercytokinemia and hyperactivation of phospho-p38 mitogen-activated protein kinase in severe human influenza A virus infection.

BACKGROUND: We postulate that hypercytokinemia plays a role in immunopathogenesis of severe human influenza. METHODS: We prospectively studied 39 consecutive patients who were hospitalized with severe influenza A virus infection. On laboratory confirmation of the diagnosis, paired acute-phase (obtained at hospital admission) and convalescent-phase (obtained >10 days after hospital admission) plasma samples were collected for assay of 11 cytokines and chemokines (interleukin [IL] 1 beta; IL-6; IL-10; IL-12p70; tumor necrosis factor alpha; IL-8; monokine induced by interferon [IFN]-gamma; IFN-inducible protein 10; monocyte chemoattractant protein 1; regulated upon activation, normal T cell-expressed and secreted; and IFN-gamma) using cytometric bead-array analysis and enzyme-linked immunosorbent assay. Simultaneously, virus concentration in the acute-phase nasopharyngeal aspirate was determined using real-time quantitative reverse-transcriptase polymerase chain reaction. Intracellular signaling molecules regulating lymphocyte activation, phospho-p38 mitogen-activated protein kinase and phospho-extracellular signal-regulated protein kinase in CD4+ and CD8+ T lymphocytes were studied in the acute-phase samples using flow cytometric analysis and were compared with results for samples from healthy control subjects. RESULTS: Statistically significant increases in plasma IL-6 (3.7-fold increase), IL-8 (2.6-fold increase), IFN-induced protein 10 (4.9-fold increase), and monokine induced by IFN-gamma (2.3-fold increase) concentrations were detected during acute illness (P < .01 for all, by Wilcoxon signed-rank test); the highest concentrations were observed on symptom days 3 and 4. Corresponding plasma cytokine and chemokine concentrations and nasopharyngeal viral loads showed statistically significant correlations (rho = 0.41, 0.49, 0.54, and 0.46, respectively; P < or = .01). Phospho-p38 mitogen-activated protein kinase expression in CD4+ lymphocytes was increased, correlating with cytokine concentrations (e.g., for IFN-induced protein 10, rho = 0.78; P < .01); phospho-extracellular signal-regulated protein kinase was suppressed. Advanced age and comorbidity were associated with aberrant IL-6, IL-8, and monokine induced by IFN-gamma responses (P < .05, by Mann-Whitney U test). An elevated IL-6 concentration was independently associated with prolonged hospitalization (hospitalization for >5 days; P = .02), adjusted for age, comorbidity, and virus load. CONCLUSIONS: Hypercytokinemia (of proinflammatory and T helper 1 cytokines) is detected in severe influenza, correlating with clinical illness and virus concentration. Hyperactivation of phospho-p38 mitogen-activated protein kinase (in T helper cells) is possibly involved. Early viral suppression may attenuate these potentially deleterious cytokine responses.