The National Institute for Communicable Diseases (NICD) has detected two polio virus strains in wastewater samples from a treatment plant in Cape Town, Western Cape. The detection is part of the NICD's routine environmental and wastewater testing aimed at proactive, population-wide disease tracking. Sakina Kamwendo spoke to a pathologist at the Centre for Vaccines and Immunology at NICD, Dr Kerrigan McCarthy.