New tool to keep an eye on Covid spread

WASTEWATER scientists across the world have been tracking the genetic material of the new coronavirus in sewer systems. Using the knowledge that infected patients shed the virus in their stools and urine, scientists can detect the genetic material of the virus at wastewater plants.

Using this information, scientists led by Yale University in the US have positively correlated the Covid-19 patient admission curve with the quantity of genetic material of SARSCoV-2 detected at a wastewater plant at a specific geolocation.

Many countries have begun a Covid-19 wastewater surveillance programme as means of tracking disease progression and understanding when peaks occur. The results complement individual testing as a means of understanding outbreak patterns.

In South Africa, the Water Research Commission (WRC) has concluded a proof-of-concept study in determining whether the genetic material is present in the sewer system in selected cities.

The WRC and partners will further the research into developing a wastewater surveillance programme that has the potential to be linked to disease-outbreak tracking.

Many developing countries are characterised by a mixture of sewered and non-sewered sanitation systems. Non-sewered systems include septic tanks, latrine systems (long-drop) and other sanitation that is not connected to a sewer system.

In South Africa, around 4 million households use latrines, and there is no metropolitan that is 100% sewered. This represents a significant number of the population that cannot be covered by the Covid-19 wastewater surveillance tool. To address the gap, the WRC and the Grundfos Foundation have partnered to develop a water quality-based surveillance tool for non-sewered settlements.

Appreciable levels of genetic material of the virus have been detected in samples recovered from a single non-sewered settlement that was undertaken during the proof-of-concept study. The next phase of research aims to determine if the virus’s genetic material can be detected in other non-sewered locations, and so develop a surveillance approach.

To our knowledge, it is the first large-scale programme globally that will monitor Sars-CoV-2 in water and sanitation samples collected from non-sewered settlements.

There are benefits for developing a water quality-based surveillance tool for non-sewered settlements.

First, most developing countries and their cities are served by non-sewered sanitation technologies. The areas generally do not have sewer systems to dispose of grey water – washing water – and faecal waste, and generally represent the more vulnerable populations which have limited financial resources and living in densely-packed, non-regulated areas. The use of shared ablution facilities is common.

Second, if the genetic material is detected in significant quantities, the data could be used to provide an early warning system.

The development of the surveillance tool can complement the sewered wastewater surveillance and develop a knowledge base that can provide a better understanding of the Covid-19 spread within countries.