Wastewater surveillance monitoring of SARS-CoV-2 variants of concern and dynamics of transmission and community burden of COVID-19.

Wastewater-based surveillance is a valuable approach for monitoring COVID-19 at community level. Monitoring SARS-CoV-2 variants of concern (VOC) in wastewater has become increasingly relevant when clinical testing capacity and case-based surveillance are limited. In this study, we ascertained the turnover of six VOC in Alberta wastewater from May 2020 to May 2022. Wastewater samples from nine wastewater treatment plants across Alberta were analysed using VOC-specific RT-qPCR assays. The performance of the RT-qPCR assays in identifying VOC in wastewater was evaluated against next generation sequencing. The relative abundance of each VOC in wastewater was compared to positivity rate in COVID-19 testing. VOC-specific RT-qPCR assays performed comparatively well against next generation sequencing; concordance rates ranged from 89% to 98% for detection of Alpha, Beta, Gamma, Omicron BA.1 and Omicron BA.2, with a slightly lower rate of 85% for Delta (p < 0.01). Elevated relative abundance of Alpha, Delta, Omicron BA.1 and BA.2 were each associated with increased COVID-19 positivity rate. Alpha, Delta and Omicron BA.2 reached 90% relative abundance in wastewater within 80, 111 and 62 days after their initial detection, respectively. Omicron BA.1 increased more rapidly, reaching a 90% relative abundance in wastewater after 35 days. Our results from VOC surveillance in wastewater correspond with clinical observations that Omicron is the VOC with highest disease burden over the shortest period in Alberta to date. The findings suggest that changes in relative abundance of a VOC in wastewater can be used as a supplementary indicator to track and perhaps predict COVID-19 burden in a population.

Number of COVID-19 cases required in a population to detect SARS-CoV-2 RNA in wastewater in the province of Alberta, Canada: Sensitivity assessment.

With a unique and large size of testing results of 1,842 samples collected from 12 wastewater treatment plants (WWTP) for 14 months through from low to high prevalence of COVID-19, the sensitivity of RT-qPCR detection of SARS-CoV-2 RNA in wastewater that correspond to the communities was computed by using Probit analysis. This study determined the number of new COVID-19 cases per 100,000 population required to detect SARS-CoV-2 RNA in wastewater at defined probabilities and provided an evidence-based framework of wastewater-based epidemiology surveillance (WBE). Input data were positive and negative test results of SARS-CoV-2 RNA in wastewater samples and the corresponding new COVID-19 case rates per 100,000 population served by each WWTP. The analyses determined that RT-qPCR-based SARS-CoV-2 RNA detection threshold at 50%, 80% and 99% probability required a median of 8 (range: 4-19), 18 (9-43), and 38 (17-97) of new COVID-19 cases /100,000, respectively. Namely, the positive detection rate at 50%, 80% and 99% probability were 0.01%, 0.02%, and 0.04% averagely for new cases in the population. This study improves understanding of the performance of WBE SARS-CoV-2 RNA detection using the large datasets and prolonged study period. Estimated COVID-19 burden at a community level that would result in a positive detection of SARS-CoV-2 in wastewater is critical to support WBE application as a supplementary warning/monitoring system for COVID-19 prevention and control.

Does normalization of SARS-CoV-2 concentrations by Pepper Mild Mottle Virus improve correlations and lead time between wastewater surveillance and clinical data in Alberta (Canada): comparing twelve SARS-CoV-2 normalization approaches.

Wastewater-based surveillance (WBS) data normalization is an analyte measurement correction that addresses variations resulting from dilution of fecal discharge by non-sanitary sewage, stormwater or groundwater infiltration. No consensus exists on what WBS normalization parameters result in the strongest correlations and lead time between SARS-CoV-2 WBS data and COVID-19 cases. This study compared flow, population size and biomarker normalization impacts on the correlations and lead times for ten communities in twelve sewersheds in Alberta (Canada) between September 2020 and October 2021 (n = 1024) to determine if normalization by Pepper Mild Mottle Virus (PMMoV) provides any advantages compared to other normalization parameters (e.g., flow, reported and dynamic population sizes, BOD, TSS, NH3, TP). PMMoV concentrations (GC/mL) corresponded with plant influent flows and were highest in the urban centres. SARS-CoV-2 target genes E, N1 and N2 were all negatively associated with wastewater influent pH, while PMMoV was positively associated with temperature. Pooled data analysis showed that normalization increased ρ-values by almost 0.1 and was highest for ammonia, TKN and TP followed by PMMoV. Normalization by other parameters weakened associations. None of the differences were statistically significant. Site-specific correlations showed that normalization of SARS-CoV-2 data by PMMoV only improved correlations significantly in two of the twelve systems; neither were large sewersheds or combined sewer systems. In five systems, normalization by traditional wastewater strength parameters and dynamic population estimates improved correlations. Lead time ranged between 1 and 4 days in both pooled and site-specific comparisons. We recommend that WBS researchers and health departments: a) Investigate WWTP influent properties (e.g., pH) in the WBS planning phase and use at least two parallel approaches for normalization only if shown to provide value; b) Explore normalization by wastewater strength parameters and dynamic population size estimates further; and c) Evaluate purchasing an influent flow meter in small communities to support long-term WBS efforts and WWTP management.

Wastewater-Based Surveillance Is an Effective Tool for Trending COVID-19 Prevalence in Communities: A Study of 10 Major Communities for 17 Months in Alberta.

The correlations between SARS-CoV-2 RNA levels in wastewater from 12 wastewater treatment plants and new COVID-19 cases in the corresponding sewersheds of 10 communities were studied over 17 months. The analysis from the longest continuous surveillance reported to date revealed that SARS-CoV-2 RNA levels correlated well with temporal changes of COVID-19 cases in each community. The strongest correlation was found during the third wave (r = 0.97) based on the population-weighted SARS-CoV-2 RNA levels in wastewater. Different correlations were observed (r from 0.51 to 0.86) in various sizes of communities. The population in the sewershed had no observed effects on the strength of the correlation. Fluctuation of SARS-CoV-2 RNA levels in wastewater mirrored increases and decreases of COVID-19 cases in the corresponding community. Since the viral shedding to sewers from all infected individuals is included, wastewater-based surveillance provides an unbiased and no-discriminate estimation of the prevalence of COVID-19 compared with clinical testing that was subject to testing-seeking behaviors and policy changes. Wastewater-based surveillance on SARS-CoV-2 represents a temporal trend of COVID-19 disease burden and is an effective and supplementary monitoring when the number of COVID-19 cases reaches detectable thresholds of SARS-CoV-2 RNA in wastewater of treatment facilities serving various sizes of populations.

Utilization rates for surgical procedures in rural and urban Canada.

OBJECTIVE: To investigate whether utilization rates of common surgical procedures are different between urban and rural Canadians in 2 provinces and to examine whether these rates are influenced by the presence and scope of local surgical programs and by the availability of different physician providers. METHODS: Utilization rates for 8 common surgical procedures (appendectomy, carpal tunnel release, closed hip fracture repair, rectal cancer surgery, joint replacement, thyroidectomy, unilateral or bilateral inguinal herniorrhaphy, and cholecystectomy) were identified in rural Alberta and rural Northern Ontario from hospital discharge records. Rural populations were characterized by 3 types of communities, based on availability of local physician and diagnostic resources. Travel time for consultations and surgery were estimated. Age-sex-adjusted rates, their standard errors, and 95% confidence intervals (CIs) were calculated for the purpose of comparisons among residents' locations using the method of direct standardization. To test a possible association between travel times and utilization rates, hierarchical linear and nonlinear modelling was used to analyze a 2-level model, with patients nested within rural hospital catchment areas in the province of Alberta. RESULTS: Utilization rates for appendectomy, cholecystectomy and carpal tunnel release are significantly greater for rural populations compared with urban in both Alberta and Northern Ontario. Rural Northern Ontario had higher rates of utilization than rural Alberta for carpal tunnel release and cholecystectomy (p < 0.01) and closed hip fracture repair (p < 0.05). No statistical differences between the provinces were noted for the remaining procedures. No difference in utilization rates was found between the 3 types of rural centres. The modelling found a significant association between travel time and use for only one procedure--carpal tunnel release. Patients who had to travel < or =1 hour had a 13% higher surgery rate. CONCLUSION: Rates of utilization were higher in rural areas for procedures where greater surgical variability is known to exist. These higher rural rates were not influenced by either the presence or scope of local surgical programs nor by the differences in providers. There was no difference in rates for procedures where previous research has shown little variability.

Rural surgical services in two Canadian provinces.

OBJECTIVE: Contrast alternative health delivery systems and the use of differently trained physician providers in the supply of surgical services to rural residents in 2 Canadian provinces. METHODS: Four surgical procedures (carpal tunnel release, inguinal herniorrhaphy, appendectomy and cholecystectomy) provided to rural residents of Alberta and Northern Ontario were identified between 1997/98 and 2001/02. Surgical staff were identified as specialists or non-specialists. Rural populations were mapped into the catchment areas of rural acute care facilities. Rural surgical programs were characterized by the level of surgical service available locally. RESULTS: Alberta and Northern Ontario have a similar number of rural surgical programs staffed by Canadian-certified general surgeons (10 and 12, respectively). However, Alberta has 27 smaller rural surgical programs staffed by non-specialist surgeons and Northern Ontario has only 4. These non-specialist surgeons play a significant role in Alberta, often in collaboration with specialist surgeons. In Northern Ontario the non-specialist surgeons play a minor role. The small rural surgical programs in Northern Ontario that are staffed by specialist surgeons are significantly more successful in retaining the local surgical caseload compared with similar programs in Alberta. CONCLUSIONS: The principal differences between Alberta and Northern Ontario in the delivery of rural surgical services are the greater number of small rural surgical programs in Alberta, and the substantial role of non-specialist surgical staff in these programs.

Research methodology for the investigation of rural surgical services.

This paper describes a functional approach to the definition of rural populations for purposes of rural health care research. Rather than define "rural" directly, we created a definition of urban populations and our research target became the non-urban component. Using Geographic Information Systems technology, isochrones (drivetime zones) were created that attached suburban populations to urban centres and mapped non-urban populations into rural hospital catchment areas. For population-based analyses, we have proposed a methodology for constructing catchment areas attached to Rural, Regional and Metropolitan services. We have developed a model for calculation of travel time for patients required to travel for care. We successfully applied these methodologies to the disparate regions of rural Alberta and Northern Ontario in 2 papers that investigated the delivery of rural surgical services. This methodology represents a durable and portable designation of "rural" with potential for research applications in other areas of health research. By defining "urban" rather than "rural," we avoided many of the methodological conundrums in this research field.

Outcomes of maternity care services in Alberta, 1999 and 2000: a population-based analysis.

OBJECTIVE: To evaluate the maternal and perinatal outcomes of Alberta's regionalized system of care. In particular, to compare the outcomes of communities with limited or no local intrapartum care with those of regional and tertiary care centres. METHODS: We conducted a population-based retrospective study of all Alberta deliveries in 1999 and 2000. Maternal outcome measures were rates of patient outflow, induction of labour, Caesarean section (CS), and participation in vaginal birth after Caesarean section (VBAC). The perinatal outcome measure was the perinatal loss rate (mortality rate plus stillbirth rate). Rural maternity care programs were categorized as follows: no elective local maternity care (level 0), local maternity care without local CS capabilities (level IA), and local maternity care with local CS capabilities (level IC). RESULTS: Communities offering intrapartum care without local CS capability delivered 22.1% of their maternity population. This proportion increased to 70.1% if the communities had local CS capabilities. Although patient outflow was associated with parity, risk, local services, and distance to an urban centre, there was a large unexplained outflow difference between communities with similar service levels. More limited local maternity care services and higher outflow rates were associated with higher rates of induction of labour. Rates for CS, participation in VBAC, and perinatal loss were not significantly different for different types of maternity care programs other than a lower CS rate for residents in type IA communities compared with other communities (18% vs. 20%). CONCLUSION: The principal consequences of a limited scope of local maternity care services for rural women is an increased rate of induction of labour and, if they live in a community that delivers babies without local CS capability (IA), a lower CS rate. These category IA communities, with patient outflows of 78%, are largely unsuccessful in having women deliver locally, but women from these communities have a lower rate of CS wherever they deliver. The 18 rural Alberta maternity care programs where patient outflow is over 67% may not be sustainable.

Comparison of two atmospheric-dispersion models to assess farm-site exposure to sour-gas processing-plant emissions.

We describe two approaches for exposure assessment that we used in a large-scale retrospective cattle study conducted in Alberta, Canada. Sulfur dioxide (SO(2)) was the surrogate measure of exposure to a complex mixture of combusted sour-gas emissions. Monthly air pollution dispersion modeling (1985-1994) (based on individual industrial source processing-plant engineering specifications, emission volumes, and meteorologic information) provided exposure isopleths of sulfur dioxide concentration from each of 231 sour-gas processing-plants across the province. In contrast, a simpler measure of proximity to source(s) of varying emission rates was applied in a geographical information system based on simplified pollution decay at increasing distances from each point source. Province-wide (663,000 km(2)) surface analysis (by exposure-level classification) produced a contingency coefficient of 0.68 between the two exposure estimates. Annual exposure estimates at the 1382 dairy and 5726 beef cow-calf farms studied were highly correlated over the 10-years period (r(spearman)=0.82 and 0.83, respectively), while monthly exposure estimates were somewhat less correlated (r(spearman)=0.80 and 0.82, respectively) for the two exposure assessment methods. Crude exposure estimates from each method were similar in both direction and magnitude.