Wastewater Sampling Methods for Water Based Epidemiology

In 2020, Public Health Departments struggled to control SARS-CoV-2 spread in communities. As infected individuals did not see any symptom for few days, they unknowingly continued spreading the virus within their community. Lots of lives were lost, and the entire healthcare system was stressed. Initially, clinical testing was the only means to detect the virus presence. However, this testing is after-the-fact and, hence, too late. As a result, control measures such as social distancing and mask mandates were implemented. Besides having a negative impact on the economy, such measures were not 100% enforceable. Tracking and preventing the outbreak was challenging. Contact tracing is one way to see where the virus was and is going, but once again it's still after-the-fact of spreading the virus. In this chaotic environment, wastewater surveillance provided a new way to track and predict the virus's spread. When an individual is infected with SARS-CoV-2, he/she sheds the virus through their stool which ends up in wastewater. When such wastewater is analyzed, it provides information on the presence of the virus, as early as seven days prior to detection through clinical testing. Similar studies were done in the past for viral outbreaks such as Polio. It is now established that Wastewater-based epidemiology (WBE) is a valuable population level approach for monitoring viral presence. Analysis on samples collected at a Wastewater treatment plant influent provides catchment-wide virus presence to establish trends. Whereas analysis on samples collected in wastewater collection system, close to source, finds virus prevalence in local area such as neighborhood, dorms, hospitals, and nursing home. Finding city-wide trends can help implement programs such as mask mandates and social distancing before it is too late. By finding virus presence in a local area, quick small-scale clinical testing can be performed to narrow down infection to individual or building levels before it is widespread. For an accurate analysis, it is critical that collected wastewater samples are source representative. Otherwise, garbage in, garbage out. This presentation will explain type samplers and sampling methods to be used based on purpose and location. The presentation will cover the following topics: - Purpose of wastewater analysis – - Detecting prevalence, Tracking, and/or Trend analysis - Target area – City, zip code, neighborhood, building (e.g. Dorm, Nursing home, Hospital) - How to select sampling location based on the above purpose – Treatment plant, collection system network, building outlet? - Types of sampling methods - Grab sampling vs composite sampling. Pros and cons - What types of samplers should be used based on location and purpose – - Permanent or portable - With or without refrigeration - What are the best sampling methods based on location, purpose, and type of sampler? - What bottle configuration should be used based on purpose – Single bottle or multi-bottles - How to transport and preserve samples. How to store samples – short term vs long term.