Wastewater surveillance of Mpox virus in Baltimore

Fluorescence damping as primary interference mechanism of humic acids on qPCR quantification of SARS-CoV-2 in wastewater surveillance

Real-time polymerase chain reaction (qPCR) is a widely used technology for the detection and quantification of nucleic acids in wastewater surveillance. However, the presence of inhibiting and/or interfering substances in wastewater samples, in particular humic acids, can significantly impact the accuracy and reliability of qPCR results. In this study, we investigated the impact of humic acids on qPCR reactions and determined the relative importance of various inhibition/interference mechanisms through spiked experiments and modeling. Our results showed that higher concentrations of humic acids led to increasing threshold cycle (CT) values, which however cannot be adequately described by the polymerase inhibition model and the DNA template complexation model. Further inspection showed that humic acids caused fluorescence damping of the FAM reporter dye, resulting in an overall decrease in fluorescence intensity. Modeling of the fluorescence damping effect showed that the CT values of qPCR reactions can be corrected based on end-point fluorescence reduction. Similar observations and corrections were also achieved when SARS-CoV-2 cDNA was spiked with an actual wastewater sludge cDNA.

Monkeypox Virus Occurrence in Wastewater Environment and Its Correlation with Incidence Cases of Mpox: A Systematic Review and Meta-Analytic Study

The COVID-19 pandemic has increased the interest in the use of wastewater-based surveillance (WBS) strategy for infectious disease monitoring, especially when clinical cases are underreported. The excretion of monkey virus (MPXV) in the feces of both symptomatic and preclinical individuals has further driven the interest in WBS applicability to MPXV monitoring in wastewater to support its mitigation efforts. We performed a systematic review with meta-analysis, using six databases to assess MPXV detection in wastewater. We performed a random-effects model meta-analysis to calculate the pooled prevalence at a 95% confidence interval (95% CI). Also, we carried out a subgroup analysis according to the country regions and a sensitivity analysis excluding studies classified as having a high risk of bias. The overall MPXV positivity rate in wastewater was estimated at 22% (95% CI: 14-30%; I2 = 94.8%), with more detection rate in North America (26%, 95% CI: 8-43%) compared to Europe and Asia (22%, 95% CI: 12-31%). The MPXV detection rate was significantly higher in 2022 studies (22%, 95% CI: 13-31%) compared to 2023 (19%, 95% CI: 14-25%). The real-time PCR platform significantly detected more MPXV (24%, 95% CI: 14-34%) than the digital droplet PCR-based studies (17%, 95% CI: 4-31%), which was used less frequently. Viral concentration with centrifugation procedure indicated higher detection rates (21%, 95% CI: 10-33%) than other known sample concentration protocols. Generally, MPXV detection rates in wastewater samples strongly correlate with incidence cases of mpox (range of R = 0.78-0.94; p < 0.05). Findings from this study suggest that WBS of MPXV could be employed as an epidemiological early warning tool for disease monitoring and mpox outbreak prediction similar to the clinical case-based surveillance strategies.

Virus Stability on Surfaces, in Bodily Fluids, in Wastewater and Different Environmental Conditions

Information concerning the fundamental properties of a pathogen is essential at the beginning of an outbreak. Often, the fundamental properties of an emerging virus are unknown because the virus is new, as in the recent SARS-CoV-2 pandemic, or because the properties have not been investigated, as was the case during the West African Ebola virus epidemic and the Marburg virus epidemics in Angola and the Democratic Republic of the Congo. The amount of time that a virus can remain viable under various conditions is one of these fundamental properties. Here we present methods for determining virus stability on surfaces, in biologically relevant matrices, and in wastewater that can be also applied to Marburg viruses.

Comparative analysis of membrane filter diameters for detection of selected viruses in wastewater samples

Wastewater serves as a valuable source of information as it contains biological markers that have been shed by infected individuals and from other biological organisms such as plants and animals. Wastewater has been proven to indicate the presence of emerging pathogens in a community before the manifestation of clinical symptoms. Several methods of concentration and nucleic acid extraction have been employed all around the world without a unified method. One such method involves the use of the adsorption extraction method (AE-method), which involves the use of electronegative membrane filters of different pore sizes. The membrane filters also differ by diameter, but no study has been reported on the effect of diameter on capture efficiency. This study was aimed at evaluating the comparative capture efficiency of two different membrane filter diameters of 45 and 90 mm with pore sizes of 0.45 μm for the detection of indicator and pathogenic viruses. Primary influent samples were obtained from two wastewater treatment plants in Baltimore, Maryland, between April 27 and June 29, 2023. A total of twenty samples were processed using 45- and 90-mm membrane filters. Nucleic acids were extracted from the filters using the QIAmp Viral RNA Mini Kit and assayed for four different targets: PMMoV, Norovirus (GI and GII), and CrAssphage by RT-qPCR. The result showed that 45 mm membrane filters had a higher combined mean capture efficiency in log10 gene copies per liter (gc/l) for crAssphage (7.40) than 90 mm membrane filters (7.10). Similarly, the 45-mm filter had higher mean capture efficiency for Norovirus GI (4.67) than the 90-mm filter (1.84) and likewise for Norovirus GII (2.14, 1.04). On the contrary, 90-mm membrane filters were observed to have better capture of PMMoV (6.84) compared to 45-mm membrane filters (6.69). This result therefore implies that 45-mm membrane filters could be more efficient for wastewater surveillance studies through the AE method for indicator viruses like CrAssphage and human disease-causing viruses like Norovirus.

Wastewater Surveillance of Mpox during the Summer Season of 2023 in Slovenia

Since COVID-19, mpox was the first emerging pathogen to have spread globally in 2022. Wastewater-based surveillance (WBS) has proven to be an efficient early warning system for detecting potential resurgences. This report aims to provide insight into the development and implementation of WBS of mpox in Slovenia and to incorporate the surveillance results into the development of public health interventions. WBS of mpox was conducted during the period from 1 June 2023 to 30 September 2023 at the wastewater treatment plant (WWTP) Ljubljana and WWTP Koper. The selected detection method of the monkeypox virus (MPXV) in the wastewater sample was based on PCR analysis. The implemented laboratory method showed that the sample preparation and concentration method enables a stable procedure for MPXV detection in wastewater samples. The laboratory analysis of wastewater samples from the selected WWTPs did not detect the MPXV during the monitoring period. In the event of MPXV detection in a wastewater sample, targeted public health interventions would be implemented, focusing on increasing awareness among the groups of men who have sex with other men and searching for positive mpox cases. We recommend that the developed system be retained in the case of an emergency epidemiological situation.

Automated robot and artificial intelligence-powered wastewater surveillance for proactive mpox outbreak prediction

In the wake of the largest-ever recorded outbreak of mpox in terms of magnitude and geographical spread in human history since May 2022, we innovatively developed an automated online sewage virus enrichment and concentration robot for disease tracking. Coupled with an artificial intelligence (AI) model, our research aims to estimate mpox cases based on the concentration of the monkeypox virus (MPXV) in wastewater. Our research has revealed a compelling link between the levels of MPXV in wastewater and the number of clinically confirmed mpox infections, a finding that is reinforced by the ability of our AI prediction model to forecast cases with remarkable precision, capturing 87 % of the data's variability. However, it is worth noting that this high precision in predictions may be related to the relatively high frequency of data acquisition and the relatively non-mobile isolated environment of the hospital itself. In conclusion, this study represents a significant step forward in our ability to track and respond to mpox outbreaks. It has the potential to revolutionize public health surveillance by utilizing innovative technologies for disease surveillance and prediction.

Wastewater surveillance for viral pathogens: A tool for public health

A focus on water quality has intensified globally, considering its critical role in sustaining life and ecosystems. Wastewater, reflecting societal development, profoundly impacts public health. Wastewater-based epidemiology (WBE) has emerged as a surveillance tool for detecting outbreaks early, monitoring infectious disease trends, and providing real-time insights, particularly in vulnerable communities. WBE aids in tracking pathogens, including viruses, in sewage, offering a comprehensive understanding of community health and lifestyle habits. With the rise in global COVID-19 cases, WBE has gained prominence, aiding in monitoring SARS-CoV-2 levels worldwide. Despite advancements in water treatment, poorly treated wastewater discharge remains a threat, amplifying the spread of water-, sanitation-, and hygiene (WaSH)-related diseases. WBE, serving as complementary surveillance, is pivotal for monitoring community-level viral infections. However, there is untapped potential for WBE to expand its role in public health surveillance. This review emphasizes the importance of WBE in understanding the link between viral surveillance in wastewater and public health, highlighting the need for its further integration into public health management.

Detection of mpox virus in wastewater provides forewarning of clinical cases in Canadian cities

Wastewater-based surveillance (WBS) has shown to be an effective tool in monitoring the spread of SARS-CoV-2 and has helped guide public health actions. Consequently, WBS has expanded to now include the monitoring of mpox virus (MPXV) to contribute to its mitigation efforts. In this study, we demonstrate a unique sample processing and a molecular diagnostic strategy for MPXV detection that can inform on the epidemiological situation of mpox outbreaks through WBS. We conducted WBS for MPXV in 22 Canadian wastewater treatment plants (WWTPs) for 14 weeks. Three MPXV qPCR assays were assessed in this study for the detection of MPXV which include the G2R assays (G2R_WA and G2R_G) developed by the Centers for Disease Control and Prevention (CDC) in 2010, and an in-house-developed assay that we have termed G2R_NML. The G2R_NML assay was designed using reference genomes from the 2022 MPXV outbreak and provides a larger qPCR amplicon size to facilitate Sanger sequencing. Results show that all three assays have similar limits of detection and are able to detect the presence of MPXV in wastewater. The G2R_NML assay produced a significantly greater number of Sanger sequence-confirmed MPXV results compared to the CDC G2R assays. Detection of MPXV was possible where provincial surveillance indicated overall low caseloads, and in some sites forewarning of up to several weeks was observed. Overall, this study proposes that WBS of MPXV provides additional information to help fill knowledge gaps in clinical case-surveillance and is potentially an essential component to the management of mpox.

From pandemic to endemic: Divergence of COVID-19 positive-tests and hospitalization numbers from SARS-CoV-2 RNA levels in wastewater of Rochester, Minnesota

Traditionally, public health surveillance relied on individual-level data but recently wastewater-based epidemiology (WBE) for the detection of infectious diseases including COVID-19 became a valuable tool in the public health arsenal. Here, we use WBE to follow the course of the COVID-19 pandemic in Rochester, Minnesota (population 121,395 at the 2020 census), from February 2021 to December 2022. We monitored the impact of SARS-CoV-2 infections on public health by comparing three sets of data: quantitative measurements of viral RNA in wastewater as an unbiased reporter of virus level in the community, positive results of viral RNA or antigen tests from nasal swabs reflecting community reporting, and hospitalization data. From February 2021 to August 2022 viral RNA levels in wastewater were closely correlated with the oscillating course of COVID-19 case and hospitalization numbers. However, from September 2022 cases remained low and hospitalization numbers dropped, whereas viral RNA levels in wastewater continued to oscillate. The low reported cases may reflect virulence reduction combined with abated inclination to report, and the divergence of virus levels in wastewater from reported cases may reflect COVID-19 shifting from pandemic to endemic. WBE, which also detects asymptomatic infections, can provide an early warning of impending cases, and offers crucial insights during pandemic waves and in the transition to the endemic phase.

A scoping review of human pathogens detected in untreated human wastewater and sludge

Wastewater monitoring is an approach to identify the presence or abundance of pathogens within a population. The objective of this scoping review (ScR) was to identify and characterize research on human pathogens and antimicrobial resistance detected in untreated human wastewater and sludge. A search was conducted up to March 2023 and standard ScR methodology was followed. This ScR included 1,722 articles, of which 56.5% were published after the emergence of COVID-19. Viruses and bacteria were commonly investigated, while research on protozoa, helminths, and fungi was infrequent. Articles prior to 2019 were dominated by research on pathogens transmitted through fecal-oral or waterborne pathways, whereas more recent articles have explored the detection of pathogens transmitted through other pathways such as respiratory and vector-borne. There was variation in sampling, samples, and sample processing across studies. The current evidence suggests that wastewater monitoring could be applied to a range of pathogens as a public health tool to detect an emerging pathogen and understand the burden and spread of disease to inform decision-making. Further development and refinement of the methods to identify and interpret wastewater signals for different prioritized pathogens are needed to develop standards on when, why, and how to monitor effectively.

Targeted community wastewater surveillance for SARS-CoV-2 and Mpox virus during a festival mass-gathering event

Wastewater surveillance has emerged recently as a powerful approach to understanding infectious disease dynamics in densely populated zones. Wastewater surveillance, while promising as a public health tool, is often hampered by slow turn-around times, complex analytical protocols, and resource-intensive techniques. In this study, we evaluated an affinity capture method and microfluidic digital PCR as a rapid approach to quantify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mpox (formerly known as monkeypox) virus, and fecal indicator, pepper mild mottle virus (PMMoV) in wastewater during a mass-gathering event. Wastewater samples (n = 131) were collected from residential and commercial manholes, pump stations, and a city's wastewater treatment plant. The use of Nanotrap® Microbiome Particles and microfluidic digital PCR produced comparable results to other established methodologies, with reduced process complexity and analytical times, providing same day results for public health preparedness and response. Using indigenous SARS-CoV-2 and PMMoV in wastewater, the average viral recovery efficiency was estimated at 10.1 %. Both SARS-CoV-2 N1 and N2 genes were consistently detected throughout the sampling period, with increased RNA concentrations mainly in wastewater samples collected from commercial area after festival mass gatherings. The mpox virus was sporadically detected in wastewater samples during the surveillance period, without distinct temporal trends. SARS-CoV-2 RNA concentrations in the city's wastewater mirrored the city's COVID-19 cases, confirming the predictive properties of wastewater surveillance. Wastewater surveillance continues to be beneficial for tracking diseases that display gastrointestinal symptoms, including SARS-CoV-2, and can be a powerful tool for sentinel surveillance. However, careful site selection and a thorough understanding of community dynamics are necessary when performing targeted surveillance during temporary mass-gathering events as potential confirmation bias may occur.

Wastewater analysis of Mpox virus in a city with low prevalence of Mpox disease: an environmental surveillance study

Background

Tracking infectious diseases at the community level is challenging due to asymptomatic infections and the logistical complexities of mass surveillance. Wastewater surveillance has emerged as a valuable tool for monitoring infectious disease agents including SARS-CoV-2 and Mpox virus. However, detecting the Mpox virus in wastewater is particularly challenging due to its relatively low prevalence in the community. In this study, we aim to characterize three molecular assays for detecting and tracking the Mpox virus in wastewater from El Paso, Texas, during February and March 2023.

Methods

In this study, a combined approach utilizing three real-time PCR assays targeting the C22L, F3L, and F8L genes and sequencing was employed to detect and track the Mpox virus in wastewater samples. The samples were collected from four sewersheds in the City of El Paso, Texas, during February and March 2023. Wastewater data was compared with reported clinical case data in the city.

Findings

Mpox virus DNA was detected in wastewater from all the four sewersheds, whereas only one Mpox case was reported during the sampling period. Positive signals were still observed in multiple sewersheds after the Mpox case was identified. Higher viral concentrations were found in the pellet than in the supernatant of wastewater. Notably, an increasing trend in viral concentration was observed approximately 1-2 weeks before the reporting of the Mpox case. Further sequencing and epidemiological analysis provided supporting evidence for unreported Mpox infections in the city.

Interpretation

Our analysis suggests that the Mpox cases in the community is underestimated. The findings emphasize the value of wastewater surveillance as a public health tool for monitoring infectious diseases even in low-prevalence areas, and the need for heightened vigilance to mitigate the spread of Mpox disease for safeguarding global health.

Funding

Center of Infectious Diseases at UTHealth, the University of Texas System, and the Texas Epidemic Public Health Institute. The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of these funding organizations.