Wastewater Surveillance

The Loxahatchee River District (LRD) is conducting Wastewater Surveillance to monitor trends of infection rates of SARS-CoV-2, the virus that causes COVID-19, within our sewer system area, which serves approximately 100,000 customers.

Wastewater, or sewage, is water from our toilets, shower, and sinks and contains human waste.  This wastewater is transported and treated at LRD’s Wastewater Treatment Facility.  LRD is working with Biobot Analytics, a leader in molecular testing of wastewater for SARS-CoV-2, to assess the prevalence of SARS-CoV-2 virus fragments in our untreated wastewater samples collected over a 24hr period at LRD’s Treatment Facility.

These SARS-CoV-2 virus fragments are shed from individuals infected with the virus, including both symptomatic and asymptomatic infections.  Because individuals shed huge amounts of SARS-CoV-2 early in their infection, even before symptoms, wastewater surveillance of SARS-CoV-2 virus fragments is a proven early indicator of COVID-19 infection rates in a community. Research has shown the relative abundance of SARS-CoV-2 virus fragments in wastewater samples correlates with and precedes clinical cases within the community by 5 to 14 days.

LRD is presently testing our wastewater for SARS-CoV-2 virus fragments twice per month.  Below we provide graphical summaries of virus fragment concentrations alongside clinical cases obtained from the Florida Department of Health for zip codes 33458, 33477 and 33469, which generally overlap with our sewer service area.  Also below are Biobot’s Laboratory Reports, links to more information, and our proposed schedule for sampling.

Notes:

  • Wastewater results updated upon receipt; NOTICE: As of June 7, 2021, FDOH is no longer publishing the clinical case counts by zip code.  We continue to seek other sources for the data.
  • To view the panel of four charts full screen, click on the double arrows on the lower right of the charts panel.  Press Esc to exit full screen.
  • To expand a single chart, hover on the chart, then click on the square with arrow in the upper right of the chart (named Focus mode), or for a mobile device tap on the chart.  To return to the panel of four charts, click on the Back to Report button on the upper left.
  • If there is a usually high FDOH case count (e.g. double the previous observation) that follows a gap or zero reading, our automated data download occurred before FDOH’s update. This data will be corrected.
  • The CDC and other scientists recommend the data presentation shown in the lower right chart.
    • Because of the exponential growth of viruses, the CDC and other scientists recommend the presentation of concentration data on a Log Scale (the figures with the orange line).  Also, because of variability in the data, the CDC and other scientists advise monitoring the general trends of data, rather than the specific concentration of virus.
    • Because of the variability in the daily case counts, the CDC and other scientists recommend presenting the 7-day rolling average of case counts.

Biobot’s Targeted Variant Detection

DateA507D Mutation; B.1.1.7A69-70 deletion; B.1.1.7 and minor regional variants not in the USY144 deletion; B.1.1.7
3/22/2021DETECTEDDETECTEDDETECTED
4/5/2021DETECTEDDETECTEDDETECTED

Biobot’s Variant Detection Methodology

The assay we have implemented targets three of the key mutations that characterize the B.1.1.7 variant, the SARS-CoV-2 variant first detected in the UK. These three mutations are highly specific to B.1.1.7 and are largely not present in other variants.  For each mutation, we provide detection results for the mutation that is found in B.1.1.7. If one of these variant-associated mutations is detected in your sample, this indicates an increased risk of presence of B.1.1.7 in your community. If two or three of these variant-associated mutations are detected in your sample, this indicates that B.1.1.7 is likely already circulating in your community. These results are summarized in the table above.

 

The limit of detection for this assay is substantially higher than for our standard SARS-CoV-2 qPCR method. Therefore, a non-detection does not necessarily indicate the absence of B.1.1.7, but rather means that the variant was potentially not present at high enough levels to be detected by this assay.  For more information visit Biobot’s Variant FAQ page: https://bit.ly/3ciZxFr.

Biobot’s Laboratory Reports

Planned Sampling Schedule

  • Schedule subject to change; last updated 7/28/2021
  • Results are generally received and posted 3 days after sampling
November 16 & 30, 2020December 14 & 28, 2020January 11 & 25, 2021
February 8 & 22, 2021March 8 & 22, 2021April 5 & 19, 2021
May 3 & 17, 2021June 1 & 14, 2021July 12 and 26, 2021
August 9 and 23, 2021September 7 and 20, 2021October 4 and 18, 2021
November 1 and 15, 2021December 6 and 20, 2021

For more information please contact Bud Howard, Director of Information Services, at bud.howard@lrecd.org or (561) 401-4037.