Sewage water analysis show KZN is in 3rd wave – experts
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DURBAN - EXPERTS from the Durban University of Technology’s Institute for Water and Wastewater Technology believe that KwaZulu-Natal is already experiencing its third wave of Covid-19 infections.
“According to recent clinical data, the number of active cases in KZN and the eThekwini Municipality began to rise steadily since April 20. However, we have started observing the spike in viral loads in wastewater since March 30, almost three weeks before the actual clinically confirmed cases were reported,” said IWWT director, Professor Faizal Bux.
“This indicates that wastewater based epidemiology may be used as a predictive tool for surges in Covid-19 infections and that frequent monitoring is required for future wave predictions,” Bux added.
According to the team, led by Bux and assisted by Professor Sheena Kumari, the peak of the second wave in South Africa occurred in January this year, with an average of 40 000 active cases in KZN.
"As a metro, the eThekwini Municipality is a good reflection of the pandemic trend in KZN. The team revealed that the viral loads at the Central Wastewater Treatment Plant during this peak period averaged at 4.72 log copies per 100ml.
“However, viral loads over the past four weeks (May 11-27, 2021) averaged at 5.57 log copies per 100ml of wastewater, which was far higher than what was observed during the peak of the second wave.
“This is indicating that eThekwini Municipality may already be experiencing the third wave of Covid-19 infections – and that there was a greater number of infected individuals within the community than what is currently being reported," he said.
Bux said they had used a scientific tool, Wastewater Based Epidemiology (WBE), which was based on the monitoring and constant analysis of viral particles shed in the stool of both symptomatic and asymptomatic infected individuals, by examining wastewater from wastewater treatment plants.
According to the research team, monitoring the changes in viral loads in wastewater over time allows them to gain insight into the levels of infection within communities.
He said the Central Wastewater Treatment Plant in Durban, KZN, which currently services around 61 suburbs within the eThekwini Municipality, has been monitored by the IWWT team at DUT since July 2020. Monitoring of this treatment plant has revealed that there was a clear correlation between the viral loads detected in wastewater and the number of reported clinical cases in KZN.
Bux said this technology can and should be expanded for application at sub-district level by testing sewage from sewer networks servicing suburbs.
The DUT team at the IWWT believes there may be more asymptomatic carriers in the community that could potentially spread the virus.
They have shared these key findings with the relevant authorities, including the provincial Department of Health and the National Institute for Communicable Diseases.