The CSIR, in collaboration with WaterLab and the University of Pretoria, is testing wastewater, primary sludge and environmental water samples for COVID-19. Wastewater-based epidemiology can be used to monitor infectious diseases, such as COVID-19 and other enteric viruses in communities.

The surveillance of wastewater for pathogens that cause diseases in a community provides a unique opportunity to assess the presence of the virus in the community without needing to test individuals. SARS-CoV-2 has been detected in sewage and found to survive for 14 days in sewage at 4°C and two days at 20°C. 

“The aim of the research is to establish testing protocols for the SARS-COV-2 virus in environmental samples, such as wastewater, primary sludge and environmental water samples, and develop an epidemiological approach of tracking COVID-19 in South Africa. Wastewater-based epidemiology is a tool used to track infections and illness in communities, instead of using clinical testing. The SARS-COV-2 has been reported in wastewater in Australia, China, France, Israel, Italy, Japan, the Netherlands and the United States of America,” says CSIR senior researcher Bettina Genthe.

The concept of screening municipal sewage as an epidemiological tool for viruses is not new, and has been successfully implemented for environmental polio virus screening, as well as early warning of Hepatitis A and Norovirus outbreaks. SARS-CoV-2 screening in raw sewage water using reverse transcription polymerase chain reaction measure the virus circulation in a defined population, for example, a city or a smaller municipality feeding from the same wastewater treatment works.

Making use of predictive modelling, wastewater can be used to estimate the number of infected individuals in the catchment via Monte Carlo simulations. The model takes the uncertainty and variation in the input parameters into consideration to predict model estimated median ranges of infected persons in a catchment and validate the results with clinical observations.

The CSIR is using its capabilities in epidemiological data management and integration with existing national reporting platforms to develop a method for comparing the estimated number of infections in communities with reported values.