Air Pollution and Respiratory Hospital Admissions in Kuwait: The Epidemiological Applicability of Predicted PM2.5 in Arid Regions.

Dust is a major component of fine particulate matter (PM2.5) in arid regions; therefore, concentrations of this pollutant in countries such as Kuwait exceed air quality standards. There is limited understanding on the impact and burden of high PM2.5 concentrations on morbidity in these countries. In this study, we explore the association of PM2.5 and the risk of respiratory hospital admissions in Kuwait. A time-series regression model was used to investigate daily variations in respiratory admissions and PM2.5 concentrations from 2010 to 2018. Due to the lack of historical air quality sampling in Kuwait, we used estimated daily PM2.5 levels from a hybrid PM2.5 prediction model. Individual and cumulative lag effects of PM2.5 over a 5-day period were estimated using distributed lag linear models. Associations were stratified by sex, age, and nationality. There were 218,749 total respiratory admissions in Kuwait during the study period. Results indicate that for every 10 µg/m3 increase in PM2.5, a 1.61% (95% CI = 0.87, 2.35%) increase in respiratory admissions followed over a 5-day cumulative lag. Our estimates show that a 10 µg/m3 reduction in average exposure will potentially avert 391 yearly respiratory admissions (95% CI = 211,571), with 265 fewer admissions among Kuwaitis (95% CI = 139,393) and 262 fewer admissions among children under 15 years of age (95% CI = 125,351). Different strata of the Kuwaiti population are vulnerable to respiratory hospitalization with short-term exposure to PM2.5, especially those under 15 years of age. The findings are informative for public health authorities in Kuwait and other dust-prone countries.

Using a stochastic continuous-time Markov chain model to examine alternative timing and duration of the COVID-19 lockdown in Kuwait: what can be done now?

BACKGROUND: Kuwait had its first COVID-19 in late February, and until October 6, 2020 it recorded 108,268 cases and 632 deaths. Despite implementing one of the strictest control measures-including a three-week complete lockdown, there was no sign of a declining epidemic curve. The objective of the current analyses is to determine, hypothetically, the optimal timing and duration of a full lockdown in Kuwait that would result in controlling new infections and lead to a substantial reduction in case hospitalizations. METHODS: The analysis was conducted using a stochastic Continuous-Time Markov Chain (CTMC), eight state model that depicts the disease transmission and spread of SARS-CoV 2. Transmission of infection occurs between individuals through social contacts at home, in schools, at work, and during other communal activities. RESULTS: The model shows that a lockdown 10 days before the epidemic peak for 90 days is optimal but a more realistic duration of 45 days can achieve about a 45% reduction in both new infections and case hospitalizations. CONCLUSIONS: In the view of the forthcoming waves of the COVID19 pandemic anticipated in Kuwait using a correctly-timed and sufficiently long lockdown represents a workable management strategy that encompasses the most stringent form of social distancing with the ability to significantly reduce transmissions and hospitalizations.

Exposures in the Indoor Environment and Prevalence of Allergic Conditions in the United States of America.

Our study examines the association of the presence of mildew, cockroaches, and pets in homes as well as household dust allergens with the prevalence and/or severity of allergic diseases. No study has concurrently assessed home environment exposures in relation to allergic conditions in the general US population. Data from 5409 participants from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) living in their current homes for ≥one year were analyzed. Multivariate logistic regression analyses between home exposures and allergic diseases prevalence and severity were performed. In adjusted analyses, mildew was associated with higher current asthma, allergies, and allergic rhinitis prevalence; endotoxin, with higher current asthma prevalence; and dust Canis familiaris (Can f) 1, with higher allergic rhinitis prevalence. However, presence of cockroaches and dust Dermatophagoides farinae (Der f) 1 were associated, respectively, with lower current asthma and allergies prevalence. Presence of mildew, dust Der f1, Dermatophagoides pteronyssinus (Der p) 1, Felis domesticus (Fel d) 1, and endotoxin were all associated with asthma and/or wheeze severity. Non-atopic asthma was more frequent with mildew and/or musty smell dust and higher dust Fel d1 concentration, while atopic asthma was more prevalent with higher Can f1 and endotoxin concentrations in dust. This study confirms previous relationships and reports novel associations, generating hypotheses for future research.

Identification of public health priorities, barriers, and solutions for Kuwait using the modified Delphi method for stakeholder consensus.

The rapid modernization and economic developments in Kuwait, have been accompanied by substantial lifestyle changes such as unhealthy diet and physical inactivity. These modifiable behaviours have contributed to increased rates of non-communicable diseases including diabetes and cardiovascular diseases. Delphi Consensus Method was implemented in the current study to draw stakeholders from all sectors together to develop a consensus on the major public health priorities, barriers and solutions. The process involves administration of a series of questions to selected stakeholders through an iterative process that ends when a consensus has been reached among participants. Results of the iteration process identified obesity, diabetes, cardiovascular diseases along with lack of enforcement of laws and regulation as priority health issues. Results also identified lack of national vision for the development of a public health system, lack of multidisciplinary research investigating sources of disease and methods of prevention and improving efficiency with existing resources in implementation and efficiency as the main barriers identified were. Solutions suggested included investing in healthcare prevention, strengthening communication between all involved sectors through intersectoral collaboration, awareness at the primary healthcare setting and use of electronic health records. The results offer an important opportunity for stakeholders in Kuwait to tackle these priority health issues employing the suggested approaches and solution.

Analysis of intervention effectiveness using early outbreak transmission dynamics to guide future pandemic management and decision-making in Kuwait.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a World Health Organization designated pandemic that can result in severe symptoms and death that disproportionately affects older patients or those with comorbidities. Kuwait reported its first imported cases of COVID-19 on February 24, 2020. Analysis of data from the first three months of community transmission of the COVID-19 outbreak in Kuwait can provide important guidance for decision-making when dealing with future SARS-CoV-2 epidemic wave management. The analysis of intervention scenarios can help to evaluate the possible impacts of various outbreak control measures going forward which aim to reduce the effective reproduction number during the initial outbreak wave. Herein we use a modified susceptible-exposed-asymptomatic-infectious-removed (SEAIR) transmission model to estimate the outbreak dynamics of SARS-CoV-2 transmission in Kuwait. We fit case data from the first 96 days in the model to estimate the effective reproduction number and used Google mobility data to refine community contact matrices. The SEAIR modelled scenarios allow for the analysis of various interventions to determine their effectiveness. The model can help inform future pandemic wave management, not only in Kuwait but for other countries as well.

Modeling the effect of lockdown timing as a COVID-19 control measure in countries with differing social contacts.

The application, timing, and duration of lockdown strategies during a pandemic remain poorly quantified with regards to expected public health outcomes. Previous projection models have reached conflicting conclusions about the effect of complete lockdowns on COVID-19 outcomes. We developed a stochastic continuous-time Markov chain (CTMC) model with eight states including the environment (SEAMHQRD-V), and derived a formula for the basic reproduction number, R0, for that model. Applying the [Formula: see text] formula as a function in previously-published social contact matrices from 152 countries, we produced the distribution and four categories of possible [Formula: see text] for the 152 countries and chose one country from each quarter as a representative for four social contact categories (Canada, China, Mexico, and Niger). The model was then used to predict the effects of lockdown timing in those four categories through the representative countries. The analysis for the effect of a lockdown was performed without the influence of the other control measures, like social distancing and mask wearing, to quantify its absolute effect. Hypothetical lockdown timing was shown to be the critical parameter in ameliorating pandemic peak incidence. More importantly, we found that well-timed lockdowns can split the peak of hospitalizations into two smaller distant peaks while extending the overall pandemic duration. The timing of lockdowns reveals that a "tunneling" effect on incidence can be achieved to bypass the peak and prevent pandemic caseloads from exceeding hospital capacity.

Analysis of the Healthcare MERS-CoV Outbreak in King Abdulaziz Medical Center, Riyadh, Saudi Arabia, June-August 2015 Using a SEIR Ward Transmission Model.

Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging zoonotic coronavirus that has a tendency to cause significant healthcare outbreaks among patients with serious comorbidities. We analyzed hospital data from the MERS-CoV outbreak in King Abdulaziz Medical Center, Riyadh, Saudi Arabia, June-August 2015 using the susceptible-exposed-infectious-recovered (SEIR) ward transmission model. The SEIR compartmental model considers several areas within the hospital where transmission occurred. We use a system of ordinary differential equations that incorporates the following units: emergency department (ED), out-patient clinic, intensive care unit, and hospital wards, where each area has its own carrying capacity and distinguishes the transmission by three individuals in the hospital: patients, health care workers (HCW), or mobile health care workers. The emergency department, as parameterized has a large influence over the epidemic size for both patients and health care workers. Trend of the basic reproduction number (R0), which reached a maximum of 1.39 at the peak of the epidemic and declined to 0.92 towards the end, shows that until added hospital controls are introduced, the outbreak would continue with sustained transmission between wards. Transmission rates where highest in the ED, and mobile HCWs were responsible for large part of the outbreak.

Prevalence and associated factors for needlestick and sharp injuries (NSIs) among dental assistants in Jeddah, Saudi Arabia.

BACKGROUND: Dental personnel are subject to exposure to a number of occupational factors including needlestick and sharp injuries (NSIs). Our study aims to address knowledge gaps on prevalence and associated factors for needlestick and sharp injuries (NSIs) for the first time in Saudi Arabia. METHODS: This cross-sectional study was conducted on a sample of 450 dental assistants recruited from 40 randomly selected private clinics in Jeddah, Saudi Arabia. Data on demographic characteristics, history of NSIs, nature of work, compliance with infection control protocols, and knowledge of infection control procedures and disease transmission were collected using a self-administered questionnaire. Logistic regression analysis was used to assess factors associated with NSIs; unadjusted and adjusted odds ratios (aORs) and their respective 95% confidence intervals (CIs) were computed. RESULTS: About three in ten dental assistants experienced at least one NSI (29.8%, 95% CI 25.6-34.2%) in private dental clinics. Lack of adequate knowledge of infection control procedures and disease transmission, non-compliance with infection control protocol of vaccination against hepatitis B virus, and attending 12 or less number of patients daily were significantly associated with increased risk of NSIs (p ≤ 0.05); adjusted odds ratios (95% CI) were 1.87 (1.18-2.97), 1.89 (1.05-3.41), and 1.63 (1.03-2.56), respectively. In addition, dental assistants working in 45.8% of dental clinics that had no infection control unit were positively associated with higher NSI risk (aOR = 2.28, 95% CI 1.45-3.57). CONCLUSION: Our study reported the prevalent nature of NSIs among dental assistants in Saudi Arabia and identified key factors that could be targeted to mitigate this preventable condition. Dental assistants would benefit from proper training on infection control protocols and procedures.

Key characteristics of 86 agents known to cause cancer in humans.

Since the inception of the International Agency for Research on Cancer (IARC) in the early 1970s, the IARC Monographs Programme has evaluated more than 1000 agents with respect to carcinogenic hazard; of these, up to and including Volume 119 of the IARC Monographs, 120 agents met the criteria for classification as carcinogenic to humans (Group 1). Volume 100 of the IARC Monographs provided a review and update of Group 1 carcinogens. These agents were divided into six broad categories: (I) pharmaceuticals; (II) biological agents; (III) arsenic, metals, fibers, and dusts; (IV) radiation; (V) personal habits and indoor combustions; and (VI) chemical agents and related occupations. Data on biological mechanisms of action (MOA) were extracted from the Monographs to assemble a database on the basis of ten key characteristics attributed to human carcinogens. After some grouping of similar agents, the characteristic profiles were examined for 86 Group 1 agents for which mechanistic information was available in the IARC Monographs up to and including Volume 106, based upon data derived from human in vivo, human in vitro, animal in vivo, and animal in vitro studies. The most prevalent key characteristic was "is genotoxic", followed by "alters cell proliferation, cell death, or nutrient supply" and "induces oxidative stress". Most agents exhibited several of the ten key characteristics, with an average of four characteristics per agent, a finding consistent with the notion that cancer development in humans involves multiple pathways. Information on the key characteristics was often available from multiple sources, with many agents demonstrating concordance between human and animal sources, particularly with respect to genotoxicity. Although a detailed comparison of the characteristics of different types of agents was not attempted here, the overall characteristic profiles for pharmaceutical agents and for chemical agents and related occupations appeared similar. Further in-depth analyses of this rich database of characteristics of human carcinogens are expected to provide additional insights into the MOA of human cancer development.

Overview of biological mechanisms of human carcinogens.

This review summarizes the carcinogenic mechanisms for 109 Group 1 human carcinogens identified as causes of human cancer through Volume 106 of the IARC Monographs. The International Agency for Research on Cancer (IARC) evaluates human, experimental and mechanistic evidence on agents suspected of inducing cancer in humans, using a well-established weight of evidence approach. The monographs provide detailed mechanistic information about all carcinogens. Carcinogens with closely similar mechanisms of action (e.g. agents emitting alpha particles) were combined into groups for the review. A narrative synopsis of the mechanistic profiles for the 86 carcinogens or carcinogen groups is presented, based primarily on information in the IARC monographs, supplemented with a non-systematic review. Most carcinogens included a genotoxic mechanism.

Development of a database on key characteristics of human carcinogens.

A database on mechanistic characteristics of human carcinogenic agents was developed by collecting mechanistic information on agents identified as human carcinogens (Group 1) by the International Agency for Research on Cancer (IARC) in the IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. A two-phase process is described for the construction of the database according to 24 toxicological endpoints, derived from appropriate test systems that were acquired from data obtained from the mechanisms sections of the IARC Monographs (Section 4) and a supplementary PubMed search. These endpoints were then aligned with 10 key characteristics of human carcinogens that reflect the broader attributes of these agents relating to the development of cancer in humans. The considerations involved in linking of toxicological endpoints to key characteristics are described and specific examples of the determination of key characteristics for six specific agents (tamoxifen, hepatitis B virus, arsenic, ultraviolet and solar radiation, tobacco smoking, and dioxin) are provided. Data for humans and animals were tabulated separately, as were results for in-vivo and for in-vitro sources of information. The database was constructed to support a separate analysis of the expression of these endpoints by 86 Group 1 carcinogens, in-vivo and in-vitro along with an analysis of the key characteristics of these agents.

Self-reported musculoskeletal symptoms among dentists in Saudi Arabia.

The following article has been retracted by the Editorial Board of Industrial Health. This original article is a duplicated article which was previously published entitled "Prevalence and risk factors of musculoskeletal symptoms among dental students and dental practitioners in Riyadh City, Saudi Arabia" in Archives of Environmental and Occupational Health, Volume 73, Number 1, 56-63, 2018 (Received June 15, 2016 and accepted February 19, 2017). In accordance with policies and procedures governing academic publication, we concluded that this article published in Industrial Health be retracted.

Injury and infection in dental clinics: Risk factors and prevention.

Needlestick and sharp instrument injuries are common in dental practice and present the risk of direct exposure to blood-borne pathogens, including hepatitis B virus. This cross-sectional study was carried out to determine the risk factors of injury and infection in three types of dental clinic in Riyadh, Saudi Arabia. A total of 274 male and 241 female dentists completed a structured questionnaire on demographic factors, compliance with infection control practices, and past exposure to injury and infection hazards. Dentists with more years of professional experience were significantly less likely to report having had an injury in the past (unadjusted odds ratios (ORs) and 95% confidence intervals (CIs) were 0.48, 0.27-0.87 and 0.38, 0.16-0.89 for dentists with 10-20 years and for those with over 20 years of experience, respectively). Greater compliance with infection control procedures was associated with significantly fewer reports of previous infection (OR 0.31, 95% CI 0.12-0.84). Experience of occupational safety training was not associated with a lower rate of injury or infection. Greater occupational safety knowledge and compliance with infection control management practices contribute to a reduced risk of injury and infection among dentists. More focused and specialized training on infection control and occupational safety is needed for all practicing dentists and dental students.

Patterns of Physical Activity and the Risk of Coronary Heart Disease: A Pilot Study.

Background: In the current study, we investigated the effect of physical activity (PA) on the risk of coronary heart disease (CHD). Methods: In total, 146 cases of CHD and 157 matched controls were included in the study. Data on sociodemographics, lifestyle, and medical history factors were collected using an interviewer-administered questionnaire. A standard World Health Organization (WHO)-based lifestyle questionnaire was used to assess PA. The risk of CHD was analyzed in relation to PA patterns using logistic regression. Results: Vigorous-intensity leisure PA was not associated with a lower risk of CHD. Subjects in the highest tertile of moderate occupational PA had a significantly lower risk of CHD compared to the lowest tertile (adjusted odds ratio (OR) 0.31, 95% confidence intervals (CI) 0.17–0.56). Subjects in the highest tertile of walking hasd an adjusted OR of 0.37 (95% CI 0.20–0.70). Subjects in the medium and highest tertiles of sedentary behavior had adjusted ORs of 2.01 (95% CI 1.06–3.79) and 3.88 (95% CI 2.14–7.02), respectively (p-value for trend < 0.001). Conclusion: The current results showed that both moderate occupational PA and walking protected against CHD. Sedentary behavior increased the risk of CHD.

Prevalence and risk factors of musculoskeletal symptoms among dental students and dental practitioners in Riyadh City, Saudi Arabia.

This study assessed the nature, prevalence, and risk factors of musculoskeletal symptoms (MS) in dental clinics. A self-administered questionnaire was completed by 515 dental students and dentists about nature of work and prevalence and frequency of MS symptoms. Chi-square and logistic regression were used to determine the association of MS with a number of important variables. Pain in the lower back (64%) and neck (60%) were the most prevalent MS. Working in the dental colleges' clinics was associated with increased risk of MS (adjusted OR 2.30, 95% CI [1.27, 4.18]). A stronger association was observed for dentists working in the private clinics (adjusted OR 2.58, 95% CI [1.28, 5.17]). Female dentists were at more risk of MS than male participants (OR 1.63, 95% CI [1.02, 2.59]). The higher risk of reported MS symptoms in women and for those working in the dental colleges and private clinics underscores the importance of recognition and prevention of MS symptoms even early in the dental profession.

Self-reported musculoskeletal symptoms among dentists in Saudi Arabia.

Musculoskeletal disorders are very common in the dental practice. This cross-sectional study assessed the nature and prevalence of musculoskeletal symptoms (MS) and their associated risk factors among dentists in three types of clinics in Riyadh. A structured, self-administered questionnaire about demographic characteristics, nature of work, and prevalence and frequency of MS was completed by 274 male and 241 female dentists. Chi-square and logistic regression were used to determine the association of MS with a number of important variables. Pain in the lower back (64%) and neck (60%) were the most prevalent MS. Working in the dental colleges' clinics was associated with increased risk of MS (adjusted OR 2.30, 95% CI 1.27-4.18). A stronger association was observed for dentists working in the private clinics (adjusted OR 2.58, 95% CI 1.28-5.17) compared to government clinics. Female dentists were at more risk of MS than the male dentists (OR 1.63, 95%CI 1.02-2.59). The OR of MS for dentists treating more than 10 patients/d was 1.53 (95%CI 0.83-2.81). The higher risk of reported MS in females and for those working in the dental colleges and private clinics underscores the importance of recognition and prevention of MS even early in the dental profession.

A stochastic model of the bovine spongiform encephalopathy epidemic in Canada.

Bovine spongiform encephalopathy (BSE) appeared in the United Kingdom in the mid 1980s, and has been attributed to the use of meat and bone meal (MBM) in cattle feed contaminated with a scrapie-like agent. Import of infectious materials from a country where BSE has occurred is believed to be the major factor underlying the spread of the BSE epidemic to other countries. This study presents a new stochastic model developed to estimate risk of BSE from importation of cattle infected with the BSE agent. The model describes the propagation of the BSE agent through the Canadian cattle herd through rendering and feeding processes, following importation of cattle with infectious prions. This model was used estimate the annual number of newly infected animals each year over the period 1980-2019. Model predictions suggested that the number of BSE infections in Canada might have been approximately 40-fold greater than the actual number of clinically diagnosed cases. Under complete compliance with the 2007 ban on feeding MBM, this model further predicts that BSE is disappearing from the Canadian cattle system. A series of sensitivity analyses was also conducted to test the robustness of model predictions to alternative assumptions about factors affecting the evolution of the Canadian BSE epidemic.

A Bayesian back-calculation method to estimate the risk of bovine spongiform encephalopathy (BSE) in Canada during the period 1996-2011.

Seventeen typical cases of bovine spongiform encephalopathy (BSE) were detected in Canada the period of 2003-2011. The clinical incidence of BSE was censored by early slaughter, death, or exportation of infected cattle due to the long incubation period of BSE disease. The aim of this study was to estimate the infection incidence of BSE in birth cohorts during 1996-2004 and project infection frequency through to 2007. An estimate of the number of asymptomatic infected cattle slaughtered for human consumption is also provided. The number of incident, asymptomatic cases was assumed to follow a Poisson process. A Bayesian back-calculation approach was used to project the risk of contracting BSE in those birth cohorts. Model parameters and inputs were taken from scientific literature and governmental data sources. The projected number of infected cattle in birth cohorts spanning the period 1996-2007 was 492, with median 95% credible interval 258-830. If the requirement to remove specified risk material (SRM) from cattle prior to entering the food chain was not in place, the predicted number of slaughtered infected in the human food chain from 1996-2010 was 298, with a 95% credible interval 156-500. The magnitude of the BSE epidemic in Canada for 1996-2007 birth cohorts was estimated to be approximately 28-fold higher than the number of clinical cases detected through to October 2011. Although some of those cattle were slaughtered for human consumption, the requirement of SRM removal may have prevented most of the infectious material from entering the food chain.

Mathematical Models for Estimating the Risks of Bovine Spongiform Encephalopathy (BSE).

When the bovine spongiform encephalopathy (BSE) epidemic first emerged in the United Kingdom in the mid 1980s, the etiology of animal prion diseases was largely unknown. Risk management efforts to control the disease were also subject to uncertainties regarding the extent of BSE infections and future course of the epidemic. As understanding of BSE increased, mathematical models were developed to estimate risk of BSE infection and to predict reductions in risk in response to BSE control measures. Risk models of BSE-transmission dynamics determined disease persistence in cattle herds and relative infectivity of cattle prior to onset of clinical disease. These BSE models helped in understanding key epidemiological features of BSE transmission and dynamics, such as incubation period distribution and age-dependent infection susceptibility to infection with the BSE agent. This review summarizes different mathematical models and methods that have been used to estimate risk of BSE, and discusses how such risk projection models have informed risk assessment and management of BSE. This review also provides some general insights on how mathematical models of the type discussed here may be used to estimate risks of emerging zoonotic diseases when biological data on transmission of the etiological agent are limited.