How Does Wastewater Epidemiology Work?

Wastewater epidemiology, better known as wastewater-based epidemiology or WBE, is the science of analysing the sewage of a local population to check for the presence of contaminants, chemicals or toxins. The practice has been used for decades to quantify infection rates of pathogens like polioviruses and bacteria, but has gained more public traction recently due to its role in assessing the extent of COVID-19 propagation.

How does wastewater epidemiology work?

As with any form of water quality monitoring, the first step in the WBE process is collecting an appropriate sample to be assessed. There are two distinct methods of WBE sample collection, known as grab sampling and composite sampling. The former relies on just a single sample taken at one moment in time, while the latter combines a collection of different samples taken at different points of a pre-determined period, which is normally 24 hours.

The sample or samples are then transferred to the lab, where they are subjected to sophisticated monitoring processes. While there are a few different methods of analysis employed by scientists around the globe, the most common one is polymerase chain reaction technology, otherwise known as PCR. You may recognise the acronym from the COVID-19 tests used to diagnose sufferers of the virus, since it’s the same process at play.

WBE and COVID-19

Although WBE has been in use for many years, it has crept onto the mainstream consciousness in the last couple of years due to its application for determining infection rates of the coronavirus. Indeed, high-throughput wastewater analysis has since become a key tool in COVID-19 surveillance, chiefly because it offers several key advantages over targeted testing.

While WBE cannot identify individual sufferers of the disease, it can monitor a larger segment of the population quickly and effectively. This gives scientists and authorities the ability to see an overview of how a community has been affected by the disease, perhaps even before symptoms become apparent, thus allowing them to divert resources and impose measures accordingly. It also does this in a non-invasive way, which can’t be said of the unpleasant lateral flow or PCR tests which individuals must take.

Other uses of WBE

Besides being used to ascertain how far COVID-19 has pervaded through a certain section of society, WBE is also used to test for a number of other diseases and viruses. Polioviruses are its main target, though it can also be instrumental in detecting other harmful bacteria and pathogens. This can allow us to gain a picture of which diseases are prevailing at any given time and place.

Meanwhile, it’s not just pathogens which WBE can detect. Its ability to identify individual chemicals also means it can play a starring role in the latest detection methods and regulatory measures for PFAS, or so-called “forever chemicals”. What’s more, it can also detect the presence of illegal drugs in a sample, indicating whether the target population uses the illicit substances and giving a general idea of the extent of the abuse.