The highly infectious Delta variant of Covid-19 has been detected in wastewater at 25 treatment plants in the Western Cape.
SA Medical Research Council (SAMRC) scientists said they made the discovery after obtaining reagents to test for the Delta variant.
“[The team] detected it as the dominant variant in towns in the Breede Valley (Worcester, Rawsonville, Touws River and De Doorns), Theewaterskloof (Bot River and Villiersdorp) as well as in 19 wastewater treatment plants in the Cape Town metropole,” said Dr Rabia Johnson, deputy director of the SAMRC biomedical research and innovation platform.
“For the past two months, SAMRC scientists have been screening for the presence of mutations associated with the Alpha and Beta variants in wastewater … and found both the Alpha and Beta variants, with the Beta variant being predominant.”
Johnson said the SAMRC team did not yet know whether busy roads play a role in Covid-19 transmission, but several towns where the Delta variant was found in wastewater were along the N1.
She said data from wastewater testing provides an overview of infections within communities and is a valuable source of information for Covid-19 decision-making.
“We hope to make testing for a range of SARS-CoV-2 variants a standard component of our weekly wastewater surveillance programme,” she said.
SAMRC president Prof Glenda Gray said tracking variants in wastewater could provide an early warning system for public health authorities.
“The emergence of new and more contagious Covid-19 strains globally and especially in SA has increased the need to keep track of variants and their presence in communities,” she said.