Factors of acute respiratory infection among under-five children across sub-Saharan African countries using machine learning approaches.

Symptoms of Acute Respiratory infections (ARIs) among under-five children are a global health challenge. We aimed to train and evaluate ten machine learning (ML) classification approaches in predicting symptoms of ARIs reported by mothers among children younger than 5 years in sub-Saharan African (sSA) countries. We used the most recent (2012-2022) nationally representative Demographic and Health Surveys data of 33 sSA countries. The air pollution covariates such as global annual surface particulate matter (PM 2.5) and the nitrogen dioxide available in the form of raster images were obtained from the National Aeronautics and Space Administration (NASA). The MLA was used for predicting the symptoms of ARIs among under-five children. We randomly split the dataset into two, 80% was used to train the model, and the remaining 20% was used to test the trained model. Model performance was evaluated using sensitivity, specificity, accuracy, and the area under the receiver operating characteristic curve. A total of 327,507 under-five children were included in the study. About 7.10, 4.19, 20.61, and 21.02% of children reported symptoms of ARI, Severe ARI, cough, and fever in the 2 weeks preceding the survey years respectively. The prevalence of ARI was highest in Mozambique (15.3%), Uganda (15.05%), Togo (14.27%), and Namibia (13.65%,), whereas Uganda (40.10%), Burundi (38.18%), Zimbabwe (36.95%), and Namibia (31.2%) had the highest prevalence of cough. The results of the random forest plot revealed that spatial locations (longitude, latitude), particulate matter, land surface temperature, nitrogen dioxide, and the number of cattle in the houses are the most important features in predicting the diagnosis of symptoms of ARIs among under-five children in sSA. The RF algorithm was selected as the best ML model (AUC = 0.77, Accuracy = 0.72) to predict the symptoms of ARIs among children under five. The MLA performed well in predicting the symptoms of ARIs and associated predictors among under-five children across the sSA countries. Random forest MLA was identified as the best classifier to be employed for the prediction of the symptoms of ARI among under-five children.

Environmental exposures associated with early childhood recurrent wheezing in the mother and child in the environment birth cohort: a time-to-event study.

BACKGROUND: Antenatal factors and environmental exposures contribute to recurrent wheezing in early childhood. AIM: To identify antenatal and environmental factors associated with recurrent wheezing in children from birth to 48 months in the mother and child in the environment cohort, using time-to-event analysis. METHOD: Maternal interviews were administered during pregnancy and postnatally and children were followed up from birth to 48 months (May 2013-October 2019). Hybrid land-use regression and dispersion modelling described residential antenatal exposure to nitrogen dioxide (NO2) and particulate matter of 2.5 µm diameter (PM2.5). Wheezing status was assessed by a clinician. The Kaplan-Meier hazard function and Cox-proportional hazard models provided estimates of risk, adjusting for exposure to environmental tobacco smoke (ETS), maternal smoking, biomass fuel use and indoor environmental factors. RESULTS: Among 520 mother-child pairs, 85 (16%) children, had a single wheeze episode and 57 (11%) had recurrent wheeze. Time to recurrent wheeze (42.9 months) and single wheeze (37.8 months) among children exposed to biomass cooking fuels was significantly shorter compared with children with mothers using electricity (45.9 and 38.9 months, respectively (p=0.03)). Children with mothers exposed to antenatal ETS were 3.8 times more likely to have had recurrent wheeze compared with those not exposed (adjusted HR 3.8, 95% CI 1.3 to 10.7). Mean birth month NO2 was significantly higher among the recurrent wheeze category compared with those without wheeze. NO2 and PM2.5 were associated with a 2%-4% adjusted increased wheezing risk. CONCLUSION: Control of exposure to ETS and biomass fuels in the antenatal period is likely to delay the onset of recurrent wheeze in children from birth to 48 months.

Childhood lower respiratory tract infections linked to residential airborne bacterial and fungal microbiota.

Residential microbial composition likely contributes to the development of lower respiratory tract infections (LRTI) among children, but the association is poorly understood. We aimed to study the relationship between the indoor airborne dust bacterial and fungal microbiota and childhood LRTI in Ibadan, Nigeria. Ninety-eight children under the age of five years hospitalized with LRTI were recruited and matched by age (±3 months), sex, and geographical location to 99 community-based controls without LRTI. Participants' homes were visited and sampled over a 14-day period for airborne house dust using electrostatic dustfall collectors (EDC). In airborne dust samples, the composition of bacterial and fungal communities was characterized by a meta-barcoding approach using amplicons targeting simultaneously the bacterial 16S rRNA gene and the internal-transcribed-spacer (ITS) region-1 of fungi in association with the SILVA and UNITE database respectively. A 100-unit change in house dust bacterial, but not fungal, richness (OR 1.06; 95%CI 1.03-1.10) and a 1-unit change in Shannon diversity (OR 1.92; 95%CI 1.28-3.01) were both independently associated with childhood LRTI after adjusting for other indoor environmental risk factors. Beta-diversity analysis showed that bacterial (PERMANOVA p < 0.001, R2 = 0.036) and fungal (PERMANOVA p < 0.001, R2 = 0.028) community composition differed significantly between homes of cases and controls. Pair-wise differential abundance analysis using both DESEq2 and MaAsLin2 consistently identified the bacterial phyla Deinococcota (Benjamini-Hochberg (BH) adjusted p-value <0.001) and Bacteriodota (BH-adjusted p-value = 0.004) to be negatively associated with LRTI. Within the fungal microbiota, phylum Ascomycota abundance (BH adjusted p-value <0.001) was observed to be directly associated with LRTI, while Basidiomycota abundance (BH adjusted p-value <0.001) was negatively associated with LRTI. Our study suggests that early-life exposure to certain airborne bacterial and fungal communities is associated with LRTI among children under the age of five years.

Kitchen Characteristics and Practices Associated with Increased PM2.5 Concentration Levels in Zimbabwean Rural Households.

Household air pollution (HAP) from biomass fuels significantly contributes to cardio-respiratory morbidity and premature mortality globally. Particulate matter (PM), one of the pollutants generated, remains the most accurate indicator of household air pollution. Determining indoor air concentration levels and factors influencing these levels at the household level is of prime importance, as it objectively guides efforts to reduce household air pollution. This paper describes household factors associated with increased PM2.5 levels in Zimbabwean rural household kitchens. Our HAP and lung health in women study enrolled 790 women in rural and urban households in Zimbabwe between March 2018 and December 2019. Here, we report data from 148 rural households using solid fuel as the primary source of fuel for cooking and heating and where indoor air samples were collected. Data on kitchen characteristics and practices were collected cross-sectionally using an indoor walk-through survey and a modified interviewer-administered questionnaire. An Air metrics miniVol Sampler was utilized to collect PM2.5 samples from the 148 kitchens over a 24 h period. To identify the kitchen features and practices that would likely influence PM2.5 concentration levels, we applied a multiple linear regression model. The measured PM2.5 ranged from 1.35 µg/m3 to 1940 µg/m3 (IQR: 52.1-472). The PM2.5 concentration levels in traditional kitchens significantly varied from the townhouse type kitchens, with the median for each kitchen being 291.7 µg/m3 (IQR: 97.2-472.2) and 1.35 µg/m3 (IQR: 1.3-97.2), respectively. The use of wood mixed with other forms of biomass was found to have a statistically significant association (p < 0.001) with increased levels of PM2.5 concentration. In addition, cooking indoors was strongly associated with higher PM2.5 concentrations (p = 0.012). Presence of smoke deposits on walls and roofs of the kitchens was significantly associated with increased PM2.5 concentration levels (p = 0.044). The study found that kitchen type, energy type, cooking place, and smoke deposits were significant predictors of increased PM2.5 concentrations in the rural households. Concentrations of PM2.5 were high as compared to WHO recommended exposure limits for PM2.5. Our findings highlight the importance of addressing kitchen characteristics and practices associated with elevated PM2.5 concentrations in settings where resources are limited and switching to cleaner fuels may not be an immediate feasible option.

Exposure-response relationship of residential dampness and mold damage with severe lower respiratory tract infections among under-five children in Nigeria.

Previous epidemiological studies demonstrated an increased risk of respiratory health effects in children and adults exposed to dampness or mold. This study investigated associations of quantitative indicators of indoor dampness and mold exposure with severe lower respiratory tract infections (LRTI) among children aged 1-59 months in Ibadan, Nigeria. Methods: In-home visits were conducted among 178 children hospitalized with LRTI matched by age (±3 months), sex, and geographical location with 180 community-based children without LRTI. Trained study staff evaluated the indoor environment using a standardized home walkthrough checklist and measured visible dampness and mold damage. Damp-moldy Index (DMI) was also estimated to quantify the level of exposure. Exposure-response relationships of dampness and mold exposure with severe LRTI were assessed using multivariable restricted cubic spline regression models adjusting for relevant child, housing, and environmental characteristics. Results: Severe LRTI cases were more often male than female (61.8%), and the overall mean (SD) age was 7.3 (1.35) months. Children exposed to dampness <0.3 m2 (odds ratio [OR] = 2.11; 95% confidence interval [CI] = 1.05, 4.36), and between 0.3 and 1.0 m2 (OR = 2.34; 95% CI = 1.01, 7.32), had a higher odds of severe LRTI compared with children not exposed to dampness. The restricted cubic spline showed a linear exposure-response association between severe LRTI and residential dampness (P < 0.001) but a nonlinear relationship with DMI (P = 0.01). Conclusions: Residential dampness and DMI were exposure-dependently associated with higher odds of severe LRTI among under-five children. If observed relationships were causal, public health intervention strategies targeted at reducing residential dampness are critically important to mitigate the burden of severe LRTI among under-five children.

Strengthening Social Compact and Innovative Health Sector Collaborations in Addressing COVID-19 in South African Workplaces.

Workplaces are nodes for Severe Acute Respiratory Syndrome Coronavirus 2 transmission and require strategies to protect workers' health. This article reports on the South African national coronavirus disease 2019 (COVID-19) strategy that sought to ensure workers' health, protect the economic activity, safeguard livelihoods and support health services. Data from the Occupational Health Surveillance System, Surveillance System of Sentinel Hospital Sites, and government databases (public sector health worker and Compensation Fund data) was supplemented by peer-reviewed articles and grey literature. A multipronged, multi-stakeholder response to occupational health and safety (OHS) policy development, risk management, health surveillance, information, and training was adopted, underpinned by scientific input, through collaboration between government, organized labour, employer bodies, academia, and community partners. This resulted in government-promulgated legislation addressing OHS, sectoral guidelines, and work-related COVID-19 worker's compensation. The OHS Workstream of the National Department of Health provided leadership and technical support for COVID-specific workplace guidelines and practices, surveillance, information, and training, as well as a workplace-based vaccination strategy.

Job and exposure intensity among hospital cleaning staff adversely affects respiratory health.

BACKGROUND: Occupational exposure to various types of cleaning agents may increase the risk of adverse respiratory health among cleaners. This study investigated the relationship between exposure to cleaning and disinfecting agents, using a job-task and exposure intensity metric, and respiratory outcomes among cleaners. METHODS: A sample of 174 cleaners was selected from three public hospitals in Durban. A questionnaire was used to collect demographic and occupational information, and spirometry, including post-bronchodilator measures, was conducted according to the American Thoracic Society guidelines and skin prick testing were performed. Exposure metrics for job tasks and chemical exposures were created using frequency and employment-lifetime duration of exposure. Multivariate analysis regression models used job task and exposure intensity metrics. RESULTS: Doctor-diagnosed asthma prevalence was 9.8%. Breathlessness with wheeze (22.4%) was the prevalent respiratory symptom. Positive responses to skin prick testing were seen in 74 (43.2%). There was a statistically significant increased risk for shortness of breath with exposure to quaternary ammonium compounds (odds ratio [OR]: 3.44; 95% confidence interval [CI]: 1.13-10.5) and breathlessness with exposure to multipurpose cleaner (OR: 0.34; CI: 0.12-0.92). The losses in percent-predicted forced expiratory volume in 1 s (FEV1) ranged from 0.3%-6.7%. Results among the bronchodilator-positive (8.6%) showed lung function losses twofold greater when compared to the total study population with percentage predicted FEV1 (-22.6 %; p < 0.000). CONCLUSION: Exposure to certain cleaning and disinfectant agents adversely affects respiratory health, particularly lung function. This effect, while seen generally among cleaning workers, is more pronounced among those with pre-existing reversible obstructive lung disease.

Impact of ambient air pollution exposure during pregnancy on adverse birth outcomes: generalized structural equation modeling approach.

BACKGROUND: Air pollution and several prenatal factors, such as socio-demographic, behavioural, physical activity and clinical factors influence adverse birth outcomes. The study aimed to investigate the impact of ambient air pollution exposure during pregnancy adjusting prenatal risk factors on adverse birth outcomes among pregnant women in MACE birth cohort. METHODS: Data for the study was obtained from the Mother and Child in the Environment (MACE) birth cohort study in Durban, South Africa from 2013 to 2017. Land use regression models were used to determine household level prenatal exposure to PM2.5, SO2 and NOx. Six hundred and fifty-six births of pregnant females were selected from public sector antenatal clinics in low socio-economic neighbourhoods. We employed a Generalised Structural Equation Model with a complementary log-log-link specification. RESULTS: After adjustment for potential prenatal factors, the results indicated that exposure to PM2.5 was found to have both significant direct and indirect effects on the risk of all adverse birth outcomes. Similarly, an increased level of maternal exposure to SO2 during pregnancy was associated with an increased probability of being small for gestational age. Moreover, preterm birth act a mediating role in the relationship of exposure to PM2.5, and SO2 with low birthweight and SGA. CONCLUSIONS: Prenatal exposure to PM2.5 and SO2 pollution adversely affected birth outcomes after controlling for other prenatal risk factors. This suggests that local government officials have a responsibility for better control of air pollution and health care providers need to advise pregnant females about the risks of air pollution during pregnancy.

Indoor bacterial and fungal aerosols as predictors of lower respiratory tract infections among under-five children in Ibadan, Nigeria.

BACKGROUND: This study aimed to investigate the association between exposure to diverse indoor microbial aerosols and lower respiratory tract infections (LRTI) among children aged 1 to 59 months in Ibadan, Nigeria. METHODS: One hundred and seventy-eight (178) hospital-based LRTI cases among under-five children were matched for age (± 3 months), sex and geographical location with 180 community-based controls (under-five children without LRTI). Following consent from caregivers of eligible participants, a child's health questionnaire, clinical proforma and standardized home-walkthrough checklist were used to collect data. Participant homes were visited and sampled for indoor microbial exposures using active sampling approach by Anderson sampler. Indoor microbial count (IMC), total bacterial count (TBC), and total fungal count (TFC) were estimated and dichotomized into high (> median) and low (≤ median) exposures. Alpha diversity measures including richness (R), Shannon (H) and Simpson (D) indices were also estimated. Conditional logistic regression models were used to test association between exposure to indoor microbial aerosols and LRTI risk among under-five children. RESULTS: Significantly higher bacterial and fungal diversities were found in homes of cases (R = 3.00; H = 1.04; D = 2.67 and R = 2.56; H = 0.82; D = 2.33) than homes of controls (R = 2.00; H = 0.64; D = 1.80 and R = 1.89; H = 0.55; D = 1.88) p < 0.001, respectively. In the multivariate models, higher categories of exposure to IMC (aOR = 2.67, 95% CI 1.44-4.97), TBC (aOR = 2.51, 95% CI 1.36-4.65), TFC (aOR = 2.75, 95% CI 1.54-4.89), bacterial diversity (aOR = 1.87, 95% CI 1.08-3.24) and fungal diversity (aOR = 3.00, 95% CI 1.55-5.79) were independently associated with LRTI risk among under-five children. CONCLUSIONS: This study suggests an increased risk of LRTI when children under the age of five years are exposed to high levels of indoor microbial aerosols.

Lagged acute respiratory outcomes among children related to ambient pollutant exposure in a high exposure setting in South Africa.

Acute ambient air pollution impacts on the respiratory health of children may be lagged across time. We determined the short-term lagged effects of particulate matter (PM2.5), sulphur dioxide (SO2), and oxides of nitrogen (NOx) on the respiratory health of children living in low-income communities. Methods: A school-based study was conducted using a repeated measures design, across summer and winter, in four schools in each of four suburbs in the Vaal Triangle, South Africa. Data for PM2.5, NOx, and SO2 were obtained from monitoring stations within close proximity of the schools. Over 10 school days in each phase, grade 4 children completed a symptoms log and lung function tests. Parents completed a child respiratory questionnaire. Generalized estimation equations models adjusted for covariates of interest in relation to lung function outcomes and air pollutants including lag effects of 1-5 days. Results: Daily PM2.5, NOx, and SO2 median concentration levels were frequently higher than international standards. Among the 280 child participants (mean age 9 years), the prevalence of symptoms based on probable asthma was 9.6%. There was a consistent increased pollutant-related risk for respiratory symptoms, except for NOx and shortness of breath. Lung function, associated with pollutant fluctuations across the different lags, was most pronounced for peak expiratory flow rate (PEFR) for PM2.5 and SO2. A preceding 5-day average SO2 exposure had the largest loss (7.5 L/minute) in PEFR. Conclusions: Lagged declines in daily lung function and increased odds of having respiratory symptoms were related to increases in PM2.5 and SO2 among a school-based sample of children.

Pneumococcal pneumonia on the job: Uncovering the past story of occupational exposure to metal fumes and dust.

The objectives of this study are to elucidate the early history of risk for pneumococcal pneumonia from occupational exposure to metal fumes and dusts, and to demonstrate the importance of searching older literature when performing reviews. We performed manual searching for articles in the Library of the Surgeon General's Office (the precursor to Index Medicus), in the Hathi Trust database, in PubMed, andby screening reference lists in literature appearing before the introduction of PubMed. An early body of literature, from the 1890s onward, recognized that pneumonia was linked to "Thomas slag," a steel industry byproduct containing iron, manganese, and lime. Researchers, mainly in Germany, showed that workers in metal-dust-exposed occupations, especially using manganese, manifested an increased incidence of pneumococcal pneumonia. An outbreak of pneumococcal pneumonia in the 1930s implicated manganese fume in its etiology. In the immediate post-World War II period, there was a brief flurry of interest in pneumonia from exposure to potassium permanganate that was soon dismissed as a chemical pneumonitis. After a hiatus of two decades, epidemiologic investigations drew attention to the pneumonia risks of welding and related metal fume exposure, bringing renewed interest to the forgotten role of pneumococcal pneumonia as an occupational disease. Occupational or environmental inhalation of manganese, iron, or irritants may be causally related to increased pneumococcal pneumonia risk. In particular, the risk associated with manganese seems to be overlooked in recent literature. An important conclusion is the importance of obtaining additional evidence through a deeper assessment of the literature in a broad historical context.

Styrene associated respiratory outcomes among reinforced plastic industry workers.

The study aim was to determine whether styrene exposure was associated with respiratory outcomes in a dose-response manner in the fibreglass reinforcement industry. Workers (n=254) from a fibreglass reinforcement factory were subjected to a standardised interview, spirometry and styrene monitoring. Cumulative exposure was calculated across different jobs and levels of exposure. Logistic regression modelling estimated risk for symptoms, respiratory diseases and lung function change across exposure tertiles. The geometric means of styrene in the General Laminating and Fitting Departments were 48.2 mg/m3 (95% CI 36.3-64.1 mg/m3) and 20.7 mg/m3 (95% CI: 15.6-27.5 mg/m3), respectively. The cumulative exposure odds ratios for chronic cough, phlegm, wheezing and breathlessness for high exposure was 3.1 (95% CI 1.1-8.6), 5.3 (95% CI 1.7-16.6), 3.3 (95% CI 1.2-9.1) and 5.5 (95% CI 1.15-26.4), respectively. The cumulative exposure associated reduction in FEV1/FVC ratio, percent predicted FEV1 and FVC was 0.01, 0.04% and 0.05%, respectively. Styrene exposure increases the risk of respiratory symptoms and is associated with reduced lung function.

Maternal exposure to indoor PM2.5 and associated adverse birth outcomes in low socio-economic households, Durban, South Africa.

The association between in utero exposure to indoor PM2.5 and birth outcomes is not conclusive. We assessed the association between in utero exposure to indoor PM2.5 , birth weight, gestational age, low birth weight, and/or preterm delivery. Homes of 800 pregnant women were assessed using a structured walkthrough questionnaire. PM2.5 measurements were undertaken in 300 of the 800 homes for a period of 24 h. Repeated sampling was conducted in 30 of these homes to determine PM2.5 predictors that can reduce within-and/or between-home variability. A predictive model was used to estimate PM2.5 levels in unmeasured homes (n = 500). The mean (SD) for PM2.5 was 37 µg/m3 (29) with a median of 28µg/m3 . The relationship between PM2.5 exposure, birth weight, gestational age, low birth weight, and preterm delivery was assessed using multivariate linear and logistic regression models. We explored infant sex as a potential effect modifier, by creating an interaction term between PM2.5 and infant sex. The odds ratio of low birth weight and preterm delivery was 1.75 (95%CI: 1.47, 2.09) and 1.21 (95%CI: 1.06, 1.39), respectively, per interquartile increase (18 µg/m3 ) in PM2.5 exposure. The reduction in birth weight and gestational age was 75 g (95%CI: 107.89, 53.15) and 0.29 weeks (95%CI: 0.40, 0.19) per interquartile increase in PM2.5 exposure. Infant sex was an effect modifier for PM2.5 on birth weight and gestational age, and the reduction in birth weight and gestational age was 103 g (95%CI: 142.98, 64.40) and 0.38 weeks (95% CI: 0.53, 0.23), respectively, for boys, and 54 g (95%CI: 91.78,15.62) and 0.23 weeks (95%CI:0.37, 0.08), respectively, for girls. Exposure to PM2.5 is associated with adverse pregnancy outcomes. To protect the population during their reproductive period, public health policy should focus on indoor PM2.5 levels.

Prenatal Air Pollution Exposure and Placental DNA Methylation Changes: Implications on Fetal Development and Future Disease Susceptibility.

The Developmental Origins of Health and Disease (DOHaD) concept postulates that in utero exposures influence fetal programming and health in later life. Throughout pregnancy, the placenta plays a central role in fetal programming; it regulates the in utero environment and acts as a gatekeeper for nutrient and waste exchange between the mother and the fetus. Maternal exposure to air pollution, including heavy metals, can reach the placenta, where they alter DNA methylation patterns, leading to changes in placental function and fetal reprogramming. This review explores the current knowledge on placental DNA methylation changes associated with prenatal air pollution (including heavy metals) exposure and highlights its effects on fetal development and disease susceptibility. Prenatal exposure to air pollution and heavy metals was associated with altered placental DNA methylation at the global and promoter regions of genes involved in biological processes such as energy metabolism, circadian rhythm, DNA repair, inflammation, cell differentiation, and organ development. The altered placental methylation of these genes was, in some studies, associated with adverse birth outcomes such as low birth weight, small for gestational age, and decreased head circumference. Moreover, few studies indicate that DNA methylation changes in the placenta were sex-specific, and infants born with altered placental DNA methylation patterns were predisposed to developing neurobehavioral abnormalities, cancer, and atopic dermatitis. These findings highlight the importance of more effective and stricter environmental and public health policies to reduce air pollution and protect human health.

Ergonomic Risk Assessment during an Informal Hand-Made Cookware Operation: Extending an Existing Model.

The work conducted in the informal sector is highly variable within and between days. Characterizing ergonomic exposures remains a challenge because of unstructured work settings and schedules. The existing ergonomic risk assessment tools have been widely used in formal work settings with a narrow range of exposure, and for predefined tasks that primarily constitute a daily routine. There is limited information in the literature on how they have been applied in informal workplaces. The aim of this study was to extend an existing risk assessment tool and to evaluate the applicability of the extended tool by assessing ergonomic exposure related to hand-made cookware operations. Eighteen hand-made cookware makers were recruited from six sites. A walkthrough risk assessment questionnaire was used to collect information on workers, tasks, work stations and workplace structures. The Rapid Upper Limb Assessment (RULA) screening tool was extended by including duration and vibration. An action priority matrix was used to guide intervention. According to the RULA action levels, the workers required investigation and changes soon, and immediate investigation and changes. The use of an action priority matrix was appropriate, and indicated that all the workers assessed were within the high to very high exposure domain and required immediate corrective measures. The methodology used proved to be an effective and reliable strategy for identifying ergonomic exposure among hand-made cookware makers.

Lagged Association between Climate Variables and Hospital Admissions for Pneumonia in South Africa.

Pneumonia is a leading cause of hospitalization in South Africa. Climate change could potentially affect its incidence via changes in meteorological conditions. We investigated the delayed effects of temperature and relative humidity on pneumonia hospital admissions at two large public hospitals in Limpopo province, South Africa. Using 4062 pneumonia hospital admission records from 2007 to 2015, a time-varying distributed lag non-linear model was used to estimate temperature-lag and relative humidity-lag pneumonia relationships. Mean temperature, relative humidity and diurnal temperature range were all significantly associated with pneumonia admissions. Cumulatively across the 21-day period, higher mean daily temperature (30 °C relative to 21 °C) was most strongly associated with a decreased rate of hospital admissions (relative rate ratios (RR): 0.34, 95% confidence interval (CI): 0.14-0.82), whereas results were suggestive of lower mean daily temperature (12 °C relative to 21 °C) being associated with an increased rate of admissions (RR: 1.27, 95%CI: 0.75-2.16). Higher relative humidity (>80%) was associated with fewer hospital admissions while low relative humidity (<30%) was associated with increased admissions. A proportion of pneumonia admissions were attributable to changes in meteorological variables, and our results indicate that even small shifts in their distributions (e.g., due to climate change) could lead to substantial changes in their burden. These findings can inform a better understanding of the health implications of climate change and the burden of hospital admissions for pneumonia now and in the future.

Association of indoor microbial aerosols with respiratory symptoms among under-five children: a systematic review and meta-analysis.

BACKGROUND: Despite the recognition of the importance of indoor microbial exposures on children's health, the role of different microbial agents in development and aggravation of respiratory symptoms and diseases is only poorly understood. This study aimed to assess whether exposure to microbial aerosols within the indoor environment are associated with respiratory symptoms among children under-5 years of age. METHODS: A systematic literature search was conducted on PubMed, Web of Science, GreenFILE, ScienceDirect, EMBASE and Cochrane library through February 2020. Studies that investigated the exposure-response relationship between components of the indoor microbial communities and respiratory symptoms among under-five children were eligible for inclusion. A random-effect meta-analysis was applied to estimate pooled relative risk (RR) and 95% confidence interval (CI) for study specific high versus low microbial exposures. The potential effect of individual studies on the overall estimate was evaluated using leave-one-out analysis, while heterogeneity was evaluated by I2 statistics using RevMan 5.3. RESULTS: Fifteen studies were eligible for inclusion in a meta-analysis. The pooled risk estimate suggested that increased microbial exposure was associated with an increased risk of respiratory symptoms [pooled relative risk (RR): 1.24 (1.09, 1.41), P = 0.001]. The association was strongest with exposure to a combination of Aspergillus, Penicillium, Cladosporium and Alternaria species [pooled RR: 1.73 (1.30, 2.31), P = 0.0002]. Stratified analysis revealed an increased risk of wheeze [pooled RR: 1.20 (1.05, 1.37), P = 0.007 and allergic rhinitis [RR: 1.18 (0.94, 1.98), P = 0.16] from any microbial exposure. CONCLUSIONS: Microbial exposures are, in general, associated with risk of respiratory symptoms. Future studies are needed to study the indoor microbiome more comprehensively, and to investigate the mechanism of these associations.

SARS-CoV-2 and helminth co-infections, and environmental pollution exposure: An epidemiological and immunological perspective.

Soil-transmitted helminths infect billions of people globally, particularly those residing in low- and middle-income regions with poor environmental sanitation and high levels of air and water pollution. Helminths display potent immunomodulatory activity by activating T helper type 2 (Th2) anti-inflammatory and Th3 regulatory immune responses. The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus that causes Coronavirus disease 2019 (COVID-19), can exacerbate Th1/Th17 pro-inflammatory cytokine production in humans, leading to a cytokine storm. Air pollutants (particulate matter, oxygen radicals, hydrocarbons and volatile organic compounds) and water pollutants (metals and organic chemicals) can also intensify Th1/Th17 immune response and could exacerbate SARS-CoV-2 related respiratory distress and failure. The present review focused on the epidemiology of SARS-CoV-2, helminths and fine particulate matter 2.5 µm or less in diameter (PM2.5) air pollution exposure in helminth endemic regions, the possible immunomodulatory activity of helminths against SARS-CoV-2 hyper-inflammatory immune response, and whether air and water pollutants can further exacerbate SARS-CoV-2 related cytokine storm and in the process hinder helminths immunomodulatory functionality. Helminth Th2/Th3 immune response is associated with reductions in lung inflammation and damage, and decreased expression levels of angiotensin-converting enzyme 2 (ACE2) receptors (SARS-CoV-2 uses the ACE2 receptors to infect cells and associated with extensive lung damage). However, air pollutants are associated with overexpression of ACE2 receptors in the epithelial cell surface of the respiratory tract and exhaustion of Th2 immune response. Helminth-induced immunosuppression activity reduces vaccination efficacy, and diminishes vital Th1 cytokine production immune responses that are crucial for combating early stage infections. This could be reversed by continuous air pollution exposure which is known to intensify Th1 pro-inflammatory cytokine production to a point where the immunosuppressive activities of helminths could be hindered. Again, suppressed activities of helminths can also be disadvantageous against SARS-CoV-2 inflammatory response. This "yin and yang" approach seems complex and requires more understanding. Further studies are warranted in a cohort of SARS-CoV-2 infected individuals residing in helminths and air pollution endemic regions to offer more insights, and to impact mass periodic deworming programmes and environmental health policies.