A probabilistic transmission and population dynamic model to assess tuberculosis infection risk

The purpose of this study was to examine tuberculosis (TB) population dynamics and to assess potential infection risk in Taiwan. A well‐established mathematical model of TB transmission built on previous models was adopted to study the potential impact of TB transmission. A probabilistic risk model was also developed to estimate site‐specific risks of developing disease soon after recent primary infection, exogenous reinfection, or through endogenous reactivation (latently infected TB) among Taiwan regions. Here, we showed that the proportion of endogenous reactivation (53–67%) was larger than that of exogenous reinfection (32–47%). Our simulations showed that as epidemic reaches a steady state, age distribution of cases would finally shift toward older age groups dominated by latently infected TB cases as a result of endogenous reactivation. A comparison of age‐weighted TB incidence data with our model simulation output with 95% credible intervals revealed that the predictions were in an apparent agreement with observed data. The median value of overall basic reproduction number (R₀) in eastern Taiwan ranged from 1.65 to 1.72, whereas northern Taiwan had the lowest R₀ estimate of 1.50. We found that total TB incidences in eastern Taiwan had 25–27% probabilities of total proportion of infected population exceeding 90%, whereas there were 36–66% probabilities having exceeded 20% of total proportion of infected population attributed to latently infected TB. We suggested that our Taiwan‐based analysis can be extended to the context of developing countries, where TB remains a substantial cause of elderly morbidity and mortality.     

Estimation of Tuberculosis Risk and Incidence under Upper Room Ultraviolet Germicidal Irradiation in a Waiting Room in a Hypothetical Scenario

Environmental control measures (ventilation, high-efficiency particulate air filtration, and upper room ultraviolet germicidal irradiation [UVGI]) are recommended to effectively control tuberculosis (TB) transmission from unsuspected TB patients in high-risk settings, but the effectiveness of their use is not often clear. This study presents a simulation model for a hypothetical hospital waiting room, in which the number of susceptible immunocompetent people in the waiting room follows a Poisson distribution (M = 5) in either low (annual number of TB patients = 5) or high TB risk settings (annual number of TB patients = 50), and used the model to evaluate the reduction of TB transmission risk by upper room UVGI. An exponential dose-response model was used for TB transmission and a two-zone model was used for evaluating the effect of upper room UVGI. Upper room UVGI reduced TB risk by 1.6-fold at 3 microW/cm2 UV irradiance in the upper room in the low TB risk setting and by 4.1-fold at 15 microW/cm2 UV irradiance in the upper room in the high TB risk setting. Use of upper room UVGI also reduced the mean annual new infection rate from 2.2 to 1.3 infections per year at 3 microW/cm2 and to 0.6 infections per year at 15 microW/cm2 in our hypothetical high-risk settings. The effect of upper room UVGI was sensitive to both vertical air velocity (air mixing) and UV irradiance level. Results from partitioning variability indicate that most variability of TB transmission risk came from waiting time in our hypothetical hospital.     

What Risks Are Chinese People Concerned About?

The aim of this study is to investigate public perceived risk on various issues in present-day China. Two surveys were conducted in urban China in 1996 and 1998. In the first survey, risk perceptions of different occupational groups are compared. Gender differences within each occupational group are also analyzed. In the second survey, participants with diverse employment status were recruited. The overall risk rankings of both surveys indicate great concern with risks that threaten national stability and economic development, and less concern with high-technology risk such as threat from a nuclear power plant. It is also found that employees from high-profit firms are more concerned about macroscopic catastrophic risks, whereas laid-off workers and employees from money-losing enterprises are more concerned about daily life or self-concerned risks. The importance of actual exposure to risk, mass media coverage, culture, and psychometric dimensions are discussed.     

A Case Study Evaluating the Risk of Infection from Middle Eastern Respiratory Syndrome Coronavirus (MERS‐CoV) in a Hospital Setting Through Bioaerosols

Middle Eastern respiratory syndrome, an emerging viral infection with a global case fatality rate of 35.5%, caused major outbreaks first in 2012 and 2015, though new cases are continuously reported around the world. Transmission is believed to mainly occur in healthcare settings through aerosolized particles. This study uses Quantitative Microbial Risk Assessment to develop a generalizable model that can assist with interpreting reported outbreak data or predict risk of infection with or without the recommended strategies. The exposure scenario includes a single index patient emitting virus‐containing aerosols into the air by coughing, leading to short‐ and long‐range airborne exposures for other patients in the same room, nurses, healthcare workers, and family visitors. Aerosol transport modeling was coupled with Monte Carlo simulation to evaluate the risk of MERS illness for the exposed population. Results from a typical scenario show the daily mean risk of infection to be the highest for the nurses and healthcare workers (8.49 × 10^?4 and 7.91 × 10^?4, respectively), and the lowest for family visitors and patients staying in the same room (3.12 × 10^?4 and 1.29 × 10^?4, respectively). Sensitivity analysis indicates that more than 90% of the uncertainty in the risk characterization is due to the viral concentration in saliva. Assessment of risk interventions showed that respiratory masks were found to have a greater effect in reducing the risks for all the groups evaluated (>90% risk reduction), while increasing the air exchange was effective for the other patients in the same room only (up to 58% risk reduction).     

Mandatory HIV/AIDS Testing: An Ethical Issue

Should HIV/AIDS testing be required for health care workers and patients? This study compared the perceptions of 64 health care professionals and 97 nursing students on mandatory HIV testing, the risk of accidental infection, the appropriate industry response to infection, and the placement of costs. Significant differences were found between the two groups. While health care professionals favored testing for patients, students favored mandatory testing for both health care workers and patients. Students also viewed the risk of HIV/AIDS infection by a patient as significantly higher than did health care workers. Overall younger respondents tended to favor mandatory testing and also thought that hospitals should bear the cost.     

Estimation of the Likelihood of Fecal–Oral HEV Transmission Among Pigs

Sources for human hepatitis E virus (HEV) infections of genotype 3 are largely unknown. Pigs are potential animal reservoirs for HEV. Intervention at pig farms may be desired when pigs are confirmed as a source for human infections, requiring knowledge about transmission routes. These routes are currently understudied. The current study aims to quantify the likelihood of pig feces in causing new HEV infections in pigs due to oral ingestion. We estimated the daily infection risk for pigs by modeling the fate of HEV in the fecal–oral (F–O) pathway. Using parameter values deemed most plausible by the authors based on current knowledge the daily risk of infection was 0.85 (95% interval: 0.03–1). The associated expected number of new infections per day was ～4 (2.5% limit 0.1, the 97% limit tending to infinity) compared to 0.7 observed in a transmission experiment with pigs, and the likelihood of feces causing the transmission approached 1. In alternative scenarios, F–O transmission of HEV was also very likely to cause new infections. By reducing the total value of all explanatory variables by 2 orders of magnitude, the expected numbers of newly infected pigs approached the observed number. The likelihood of F–O transmission decreased by decreasing parameter values, allowing for at most 94% of infections being caused by additional transmission routes. Nevertheless, in all scenarios F–O transmission was estimated to contribute to HEV transmission. Thus, despite the difficulty in infecting pigs with HEV via oral inoculation, the F–O route is likely to cause HEV transmission among pigs.     

Quantitative Risk Assessment of Norovirus Transmission in Food Establishments: Evaluating the Impact of Intervention Strategies and Food Employee Behavior on the Risk Associated with Norovirus in Foods

We developed a quantitative risk assessment model using a discrete event framework to quantify and study the risk associated with norovirus transmission to consumers through food contaminated by infected food employees in a retail food setting. This study focused on the impact of ill food workers experiencing symptoms of diarrhea and vomiting and potential control measures for the transmission of norovirus to foods. The model examined the behavior of food employees regarding exclusion from work while ill and after symptom resolution and preventive measures limiting food contamination during preparation. The mean numbers of infected customers estimated for 21 scenarios were compared to the estimate for a baseline scenario representing current practices. Results show that prevention strategies examined could not prevent norovirus transmission to food when a symptomatic employee was present in the food establishment. Compliance with exclusion from work of symptomatic food employees is thus critical, with an estimated range of 75–226% of the baseline mean for full to no compliance, respectively. Results also suggest that efficient handwashing, handwashing frequency associated with gloving compliance, and elimination of contact between hands, faucets, and door handles in restrooms reduced the mean number of infected customers to 58%, 62%, and 75% of the baseline, respectively. This study provides quantitative data to evaluate the relative efficacy of policy and practices at retail to reduce norovirus illnesses and provides new insights into the interactions and interplay of prevention strategies and compliance in reducing transmission of foodborne norovirus.     

Your work may be killing you! Workaholism,sleep problems and cardiovascular risk

This study tests the relationships between workaholism (i.e. working excessively and compulsively), sleep problems and cardiovascular risk in 537 employees from five Spanish hospitals. Four types of worker (i.e. workaholics, positive workers, compulsive workers and hard workers) were distinguished, and their health indicators were compared. The results showed that workaholics experienced significantly more sleep problems (i.e. morning tiredness, sleeping while driving and sleeping fewer hours both on weekdays and at weekends, with poorer quality), had higher relative risk scores, and consumed more caffeine and alcohol than the other patterns of worker (positive, compulsive and hard workers). Further analyses revealed that sleep problems fully mediated the relationship between workaholism (i.e. working excessively and compulsively) and cardiovascular risk. The study emphasizes the fact that being a workaholic might be a significant risk factor for having sleep problems and cardiovascular disease.     

Risk Perception Among Nuclear Power Plant Personnel: A Survey

This study investigated risk perception, well-being, and organizational commitment among nuclear power plant personnel. The study group, 428 employees from a nuclear power plant, completed a questionnaire which included the same questions as those in previous surveys on risk perception of lay persons and industrial workers. Hazards at work were not seen as a sizable problem by nuclear power plant personnel. The study group estimated the safety of nuclear power plants better and the possibility of a serious nuclear accident as more unlikely than the general public. Compared to employees in other industrial companies, the overall perceived risks at work among plant personnel did not exceed the respective perceptions of the reference groups. Risk-related attitudes did not explain well-being among plant personnel, but the relationship between the perceived probability of a serious nuclear accident at work and organizational commitment yielded to a significant correlation: Those plant workers who estimated the likelihood of an accident higher were less committed to the organization.     

A Risk Assessment Model to Evaluate the Role of Fecal Contamination in Recreational Water on the Incidence of Cryptosporidiosis at the Community Level in Ontario

A quantitative microbial risk assessment model was developed to simulate the role of recreational water contact in the transmission of cryptosporidiosis in a model Ontario community. Stochastic simulations were based on plausible modes of contamination of a pool (literature derived), river (site-specific), and recreational lakes (literature derived). The highest estimated risks of infection were derived from the (highly contaminated) recreational lake scenario, considered the upper end for risk of infection for both children (10 infections per 1,000 swims [5‰: two infections per 1,000 swims; 95‰: three infections per 100 swims]) and adults (four infections per 1,000 swims [5‰: four infections per 1,000 swims; 95‰: one infection per 100 swims]). Simulating the likely  Cryptosporidium  oocyst concentration in a lane pool that a child would be exposed to following a diarrheal fecal release event resulted in the third highest mean risk of infection (four infections per 10,000 swims [5‰: three infections per 100,000; 95‰: 10 infections per 10,000 swims]). The findings from this study illustrate the need for systematic and standardized research to quantify  Cryptosporidium  oocyst levels in Canadian public pools and recreational beaches. There is also a need to capture the swimming practices of the Canadian public, including most common forms and frequency measures. The study findings suggest that swimming in natural swim environments and in pools following a recent fecal contamination event pose significant public health risks. When considering these risks relative to other modes of cryptosporidiosis transmission, they are significant.     

Does job complexity mitigate the negative effect of emotion-rule dissonance on employee burnout?

In interactions with clients or patients, human service workers are at risk of experiencing discrepancies between felt and organizationally mandated emotions (i.e. emotion-rule dissonance). Given the documented detrimental effects of such discrepancies on employee strain, the present study investigated whether job complexity mitigates the relation between emotion-rule dissonance and employee burnout using data from a two-wave panel study of eldercare workers (N?=?583, 16-month time lag). Structural equation modelling revealed that emotion-rule dissonance at Time 1 preceded emotional exhaustion and depersonalization at Time 2. Beyond that, employees whose work offered job complexity were found to suffer less from emotional exhaustion and depersonalization when encountering discrepancies between felt and stipulated emotions compared to employees who conducted noncomplex work. Thus, designing complex tasks appears to be a crucial starting point for alleviating employee burnout in jobs that provoke emotion-rule dissonance.     

Skill utilization and well-being: a cross-level story of day-to-day fluctuations and personal intrinsic values

The opportunity to use one's skills at work is an important prerequisite for employee well-being. Drawing on self-determination and person-environment fit theory, this diary study aims to add to our understanding of this important phenomenon in two ways. Firstly, we examine the associations of within-subject daily variations in skill utilization with well-being. Secondly, we model work value orientation as a between-subject factor that moderates this within-subject relationship. Specifically, we advocate that daily skill utilization is more beneficial (in terms of more daily work engagement and less daily emotional exhaustion) for employees holding predominantly intrinsic (i.e. self-development, community contribution) as opposed to extrinsic (i.e. financial success, status) values. Results of multilevel modelling using diary data from 99 service workers over five working days, supported the assumption that daily skill utilization was positively related to daily work engagement, particularly among employees holding a predominantly intrinsic work value orientation. Contrary to our expectations, daily skill utilization was unrelated to daily exhaustion, both for employees holding high and low intrinsic values. The discussion highlights the importance of, and employees’ receptiveness to, variations in beneficial working conditions.     

Characterizing the Risk of Infection from Mycobacterium tuberculosis in Commercial Passenger Aircraft Using Quantitative Microbial Risk Assessment

Quantitative microbial risk assessment was used to predict the likelihood and spatial organization of Mycobacterium tuberculosis ( Mtb ) transmission in a commercial aircraft. Passenger exposure was predicted via a multizone Markov model in four scenarios: seated or moving infectious passengers and with or without filtration of recirculated cabin air. The traditional exponential ( k  = 1) and a new exponential ( k  = 0.0218) dose-response function were used to compute infection risk. Emission variability was included by Monte Carlo simulation. Infection risks were higher nearer and aft of the source; steady state airborne concentration levels were not attained. Expected incidence was low to moderate, with the central 95% ranging from 10⁻⁶ to 10⁻¹ per 169 passengers in the four scenarios. Emission rates used were low compared to measurements from active TB patients in wards, thus a "superspreader" emitting 44 quanta/h could produce 6.2 cases or more under these scenarios. Use of respiratory protection by the infectious source and/or susceptible passengers reduced infection incidence up to one order of magnitude.     

A Probabilistic Transmission Model to Assess Infection Risk from Mycobacterium Tuberculosis in Commercial Passenger Trains

The objective of this article is to characterize the risk of infection from airborne Mycobacterium tuberculosis bacilli exposure in commercial passenger trains based on a risk‐based probabilistic transmission modeling. We investigated the tuberculosis (TB) infection risks among commercial passengers by inhaled aerosol M. tuberculosis bacilli and quantify the patterns of TB transmission in Taiwan High Speed Rail (THSR). A deterministic Wells‐Riley mathematical model was used to account for the probability of infection risk from M. tuberculosis bacilli by linking the cough‐generated aerosol M. tuberculosis bacilli concentration and particle size distribution. We found that (i) the quantum generation rate of TB was estimated with a lognormal distribution of geometric mean (GM) of 54.29 and geometric standard deviation (GSD) of 3.05 quantum/h at particle size ≤ 5 μm and (ii) the basic reproduction numbers (R₀) were estimated to be 0.69 (0.06–6.79), 2.82 (0.32–20.97), and 2.31 (0.25–17.69) for business, standard, and nonreserved cabins, respectively. The results indicate that commercial passengers taking standard and nonreserved cabins had higher transmission risk than those in business cabins based on conservatism. Our results also reveal that even a brief exposure, as in the bronchoscopy cases, can also result in a transmission when the quantum generation rate is high. This study could contribute to a better understanding of the dynamics of TB transmission in commercial passenger trains by assessing the relationship between TB infectiousness, passenger mobility, and key model parameters such as seat occupancy, ventilation rate, and exposure duration.     

Quantitative Assessment of the Risk of Release of Foot‐and‐Mouth Disease Virus via Export of Bull Semen from Israel

Various foot‐and‐mouth disease (FMD) virus strains circulate in the Middle East, causing frequent episodes of FMD outbreaks among Israeli livestock. Since the virus is highly resistant in semen, artificial insemination with contaminated bull semen may lead to the infection of the receiver cow. As a non‐FMD‐free country with vaccination, Israel is currently engaged in trading bull semen only with countries of the same status. The purpose of this study was to assess the risk of release of FMD virus through export of bull semen in order to estimate the risk for FMD‐free countries considering purchasing Israeli bull semen. A stochastic risk assessment model was used to estimate this risk, defined as the annual likelihood of exporting at least one ejaculate of bull semen contaminated with viable FMD virus. A total of 45 scenarios were assessed to account for uncertainty and variability around specific parameter estimates and to evaluate the effect of various mitigation measures, such as performing a preexport test on semen ejaculates. Under the most plausible scenario, the annual likelihood of exporting bull semen contaminated with FMD virus had a median of 1.3 * 10^?7 for an export of 100 ejaculates per year. This corresponds to one infected ejaculate exported every 7 million years. Under the worst‐case scenario, the median of the risk rose to 7.9 * 10^?5, which is equivalent to the export of one infected ejaculate every 12,000 years. Sensitivity analysis indicated that the most influential parameter is the probability of viral excretion in infected bulls.     

Do Teleworkers Possess Higher Levels of Public Service Motivation?

A survey conducted on U.S. federal government employees was analyzed, and the results indicate that federal workers who telecommuted frequently (i.e., those teleworking 4 to 5 days a week) reported higher levels of PSM than federal workers who did not telecommute frequently. The results also revealed that frequent teleworkers reported higher levels of PSM than employees teleworking less than 1 day a week and employees teleworking 1 day a week. However, frequent teleworkers were not found to report higher levels of PSM than employees teleworking 2 to 3 days a week.     

A Probabilistic Transmission Dynamic Model to Assess Indoor Airborne Infection Risks

The purpose of this article is to quantify the public health risk associated with inhalation of indoor airborne infection based on a probabilistic transmission dynamic modeling approach. We used the Wells-Riley mathematical model to estimate (1) the CO2 exposure concentrations in indoor environments where cases of inhalation airborne infection occurred based on reported epidemiological data and epidemic curves for influenza and severe acute respiratory syndrome (SARS), (2) the basic reproductive number, R0 (i.e., expected number of secondary cases on the introduction of a single infected individual in a completely susceptible population) and its variability in a shared indoor airspace, and (3) the risk for infection in various scenarios of exposure in a susceptible population for a range of R0. We also employ a standard susceptible-infectious-recovered (SIR) structure to relate Wells-Riley model derived R0 to a transmission parameter to implicate the relationships between indoor carbon dioxide concentration and contact rate. We estimate that a single case of SARS will infect 2.6 secondary cases on average in a population from nosocomial transmission, whereas less than 1 secondary infection was generated per case among school children. We also obtained an estimate of the basic reproductive number for influenza in a commercial airliner: the median value is 10.4. We suggest that improving the building air cleaning rate to lower the critical rebreathed fraction of indoor air can decrease transmission rate. Here, we show that virulence of the organism factors, infectious quantum generation rates (quanta/s by an infected person), and host factors determine the risk for inhalation of indoor airborne infection.     

Air Nicotine and Saliva Cotinine as Indicators of Workplace Passive Smoking Exposure and Risk1

We model nicotine from environmental tobacco smoke (ETS) in office air and salivary cotinine in nonsmoking U.S. workers. We estimate that: an average salivary cotinine level of 0.4 ng/ml corresponds to an increased lifetime mortality risk of 1/1000 for lung cancer, and 1/100 for heart disease; >95% of ETS-exposed office workers exceed OSHA's significant risk level for heart disease mortality, and 60% exceed significant risk for lung cancer mortality; 4000 heart disease deaths and 400 lung cancer deaths occur annually among office workers from passive smoking in the workplace, at the current 28% prevalence of unrestricted smoking in the office workplace.     

A probabilistic epidemiological model for infectious diseases: The case of COVID-19 at global-level

This study has developed a probabilistic epidemiological model a few weeks after the World Health Organization declared COVID-19 a pandemic (based on the little data available at that time). The aim was to assess relative risks for future scenarios and evaluate the effectiveness of different management actions for 1 year ahead. We quantified, categorized, and ranked the risks for scenarios such as business as usual, and moderate and strong mitigation. We estimated that, in the absence of interventions, COVID-19 would have a 100% risk of explosion (i.e., more than 25% infections in the world population) and 34% (2.6 billion) of the world population would have been infected until the end of simulation. We analyzed the suitability of model scenarios by comparing actual values against estimated values for the first 6 weeks of the simulation period. The results proved to be more suitable with a business-as-usual scenario in Asia and moderate mitigation in the other continents. If everything went on like this, we would have 55% risk of explosion and 22% (1.7 billion) of the world population would have been infected. Strong mitigation actions in all continents could reduce these numbers to, 7% and 3% (223 million), respectively. Although the results were based on the data available in March 2020, both the model and probabilistic approach proved to be practicable and could be a basis for risk assessment in future pandemic episodes with unknown virus, especially in the early stages, when data and literature are scarce.     

Annual Burden of Occupationally‐Acquired Influenza Infections in Hospitals and Emergency Departments in the United States

Infections among health‐care personnel (HCP) occur as a result of providing care to patients with infectious diseases, but surveillance is limited to a few diseases. The objective of this study is to determine the annual number of influenza infections acquired by HCP as a result of occupational exposures to influenza patients in hospitals and emergency departments (EDs) in the United States. A risk analysis approach was taken. A compartmental model was used to estimate the influenza dose received in a single exposure, and a dose–response function applied to calculate the probability of infection. A three‐step algorithm tabulated the total number of influenza infections based on: the total number of occupational exposures (tabulated in previous work), the total number of HCP with occupational exposures, and the probability of infection in an occupational exposure. Estimated influenza infections were highly dependent upon the dose–response function. Given current compliance with infection control precautions, we estimated 151,300 and 34,150 influenza infections annually with two dose–response functions (annual incidence proportions of 9.3% and 2.1%, respectively). Greater reductions in infectious were achieved by full compliance with vaccination and IC precautions than with patient isolation. The burden of occupationally‐acquired influenza among HCP in hospitals and EDs in the United States is not trivial, and can be reduced through improved compliance with vaccination and preventive measures, including engineering and administrative controls.