Lab Matters Fall 2024 | Page 138

APHL 2024 POSTER ABSTRACTS

national level ( https :// www . cdc . gov / nwss / rv / COVID19-variants . html ).

Wastewater surveillance can be used to track the variant proportions and mutations of SARS-CoV-2 at the community level , serving as an indicator of the ever-changing infection levels of currently circulating and emerging variants in sewered communities . In combination with clinical surveillance and other epidemiologic approaches , wastewater surveillance serves as a tool that can supplement our understanding of the spread and mutation of pathogenic diseases .

Presenter : Rakin Choudhury , uec4 @ cdc . gov

Using Wastewater Surveillance for Mpox as a Complement to Traditional Case-based Reporting in Chicago , March – June 2023

D . Foulkes 1 , A . Kittner 1 , C . Korban 1 , K . Anderson 1 , P . DeJonge 1 , E . Faherty 2 , J . Kerins 1 , R . Poretsky 3 , M . Pierce 4 , R . Atwater 1 , I . Tabidze 1 , M . Pacilli 1 , Chicago Department of Public Health 1 , CDC Contractor 2 , University of Illinois at Chicago 3 , Current Water Organization 4

Introduction : From March 18 – June 12 , 2023 , a Monkeypox Virus ( MPXV ) or mpox cluster with 40 laboratory-confirmed cases occurred in Chicago , Illinois . On May 18 , 2023 , the Chicago Department of Public Health ( CDPH ) began prospective and retrospective wastewater surveillance ( WS ) for mpox . In partnership with an academic laboratory , Discovery Partners Institute ( DPI ), CDPH sought to use MPXV detections in WS to supplement geographic and temporal knowledge of the local mpox outbreak .

Methods : WS samples were collected weekly from eight neighborhood sewer sites and three pumping stations ( i . e ., capturing influent from multiple neighborhood sewer sheds ). Additionally , WS samples were collected from two buildings in a congregate living facility . Sewer shed sites throughout the city were selected to represent all six Healthy Chicago Equity Zones . DPI-developed laboratory methods were used to test for MPXV in WS samples . FDA EUA CDC sequences designed for clinical assays were used to develop the environmental assay by DPI . With a low per capita prevalence of mpox and assay sensitivity in Chicago , quantitative concentration values were categorized as either “ detect ” or “ non-detect .” A positive MPXV detection was defined as detecting at least one of the two genes of interest at greater than or equal to the assay limit of detection ( LOD ). PCR genes of interest : 1 ) WHO-hMPXV Clade II only and 2 ) GT-hMPXV for Clades I and II . The WHO-hMPXV LOD is 1,987.5 gene copies / L and the GT-hMPXV LOD is 2,025 gene copies / L . Genes of interest require three gene copies per milliliter . Two WS samples were run in duplicate . If one or more of the four results were positive for the genes of interest , then that was a positive MPXV detection .

Results : Throughout the mpox cluster , MPXV was detected in the WS samples . Across city sampling sites , ≥1 detection was reported in seven ( 88 %) sewer shed locations and three ( 100 %) pumping stations ; overall , MPXV was detected in all but one surveillance week . Only eight out of 28 MPXV detections ( 28.6 %) were associated with a corresponding laboratory-confirmed case of mpox residing within the sampled sewer shed . MPXV has also been detected in five out of 13 ( 38 %) samples from the congregate living facility despite no associated laboratory-confirmed mpox cases among residents . WS detected MPXV at multiple sites in the four weeks preceding the clinical recognition of the mpox cluster . Residential addresses of cases in this mpox cluster were compared with the WS sewer shed location of mpox detections . MPXV was detected in sewer sheds without reported mpox cases and cases were reported without WS sewer shed detections .

Conclusions : WS indicated that although the cluster of laboratoryconfirmed mpox cases was centered in one neighborhood , mpox illness was likely more widespread , given positive detections throughout the city . The persistent , retrospective detections of MPXV seven weeks before case-based identification of a mpox cluster indicated ongoing low-level transmission in the city . MPXV detections without corresponding clinical cases highlight areas in which cases are underreported or underdetected . CDPH expanded outreach efforts to these sites ( e . g ., vaccination campaigns and provider education ). The inability to quantify the movement of the population across sewer sheds ( e . g ., commuters and non-resident travelers ) is a limitation of this study .

Presenter : Dorothy Foulkes , dorothy . foulkes @ cityofchicago . org

Viral Pathogen Testing Validation in Wastewater Using Digital Polymerase Chain Reaction on the QIAcuity Four

E . Moran 1 , W . Renquist 2 , R . Jepson 2 , C . Cass 2 , M . Pentella 2 , Centers for Disease Control and Prevention 1 , The State Hygienic Laboratory at the University of Iowa 2

Wastewater pathogen surveillance provides community-level data that might not be captured by clinical testing . By monitoring seasonal wastewater pathogen trends , health departments can improve disease surge response . To expand Iowa ’ s wastewater program beyond SARS-CoV-2 testing , we validated wastewater tests for influenza A and B viruses ( IAV , IBV ), respiratory syncytial virus ( RSV ) and SARS-CoV-2 on a new testing platform , the QIAGEN QIAcuity Four Digital PCR ( dPCR ) system and for SARS-CoV-2 , compared the newly validated method with the existing method .

Using QIAcuity , we tested two GT Molecular kits : the GT-Digital Influenza and SARS-CoV-2 Wastewater Surveillance Multiplex Assay Kit and the GT-Digital RSV Wastewater Surveillance Assay Kit . The limit of blank ( LOB ), limit of detection ( LOD ) and limit of quantitation ( LOQ ) were determined for each target ( IAV , IBV , RSV and SARS- CoV-2 ) by testing viral concentrations in wastewater ranging from 0-94,500 copies / mL . To assess dPCR stability at QIAcuity ’ s maximum capacity , we compared virus concentrations across 4 plate replicates held at room temperature ≤6 hours in the machine . To compare performance and determine if results agreed between the existing test , Bio-Rad PREvalence digital droplet PCR SARS- CoV-2 Wastewater Quantification Kit on the QX ONE and the new GT Molecular SARS-CoV-2 test , we tested 10 wastewater samples over 2 days ( 20 total tests ) on both platforms . Samples were tested with 2 different matrix recovery control spikes ( 40 per platform ).

The GT Molecular Influenza / SARS-CoV-2 and RSV Assays consistently detected both high- and low-level targets regardless of additional viral targets . LOB , LOD and LOQ ( at copies / L ) were determined as follows : LOB 0 ( IAV , IBV and RSV ) and 2,600 ( SARS- CoV-2 ); LOD 6,825 ( IAV ), 11,034 ( IBV ), 10,312 ( SARS-CoV-2 ) and 7,096 ( RSV ); LOQ 28,971 ( IAV ), 14,786 ( IBV ), 11,213 ( SARS-CoV-2 ) and 49,087 ( RSV ). In the dPCR stability study , IAV , IBV , SARS-CoV-2