Sewage could be used to tell where Covid-19 hotspots are

It is now possible to monitor the viral load of Covid-19 throughout South Africa’s biggest cities, after a commercial laboratory became the first in the world to extract Covid-19 RNA from various sewage samples in the country.

This was done as a proof of concept, after the Dutch research agency KWR entered into an agreement with the SA Business Water Chamber on 9 April this year.

In a statement released this morning, the UFS said KWR first demonstrated the potential of wastewater surveillance to identify the total viral load in a defined population in the Netherlands opening a new chapter in wastewater epidemiology on a global scale.

Prof Anthony Turton from the Centre for Environmental Management at the University of the Free State (UFS) says it is now possible to monitor the total viral load in each of the 824 wastewater treatment works in South Africa.

“Once the population size within the catchment area of the works is known, a calculation of the total viral load is possible, with a reasonable degree of accuracy. This accuracy will improve over time as the technology becomes more robust,” the statement reads.

Prof Turton said it took just eight weeks after reaching the agreement with KWR to find a laboratory with the necessary capabilities and to conduct the first tests. This was accomplished through private funding and was designed to achieve two specific objectives.

“The main objective was to determine whether the Dutch methodology could be replicated in South Africa without major investment into training and procurement of laboratory equipment. The secondary objective was to understand the logistical complexities of sampling at multiple sewage works in one province, and then safely transporting those samples to the laboratory in another province. This emulates what will be needed if this methodology is adopted by government and rolled out across all provinces as required.”

Samples were taken over a 24-hour period using an automatic bulk sampler and a number of sewage works were sampled to emulate the complexity of a national operation should rapid implementation be required. The first samples were taken on Thursday 4 June.

According to the statement, Covid-19 RNA was successfully extracted on Monday 8 June.

A second sampling run will take place shortly, implementing lessons learned from the first.

Lessons learned during the logistical exercise will be applied to streamline the operation and generate an accurate costing of the service.

“By comparing the data for each sampling sequence, it will be possible to determine with a considerable degree of accuracy whether the total viral load in a given population is increasing or decreasing. When applied to multiple sewage works, it will be possible to identify hotspots for appropriate government intervention.

“This technical capability will provide robust information to both government and private sector decision-makers as they navigate their way through the complexity of a shutdown and phased re-opening of the national economy. Rapid upskilling of suitably qualified personnel will be needed, and the UFS will be playing a role in that process.”

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