Environmental surveillance in polio programs commonly involves testing which type of environmental sample?

• A. Sewage
• B. Blood
• C. Saliva
• D. Meat

Answer: (A)

In environmental poliovirus surveillance, wastewater or sewage testing is used because people infected with poliovirus shed the virus in their stool, and this ends up in the sewage system. Analyzing sewage allows public health teams to detect the presence of circulating virus across a whole community, including people who don’t show symptoms, providing an early warning and helping guide vaccination and response efforts. Blood samples would show antibodies and not the current circulating virus in the population, so they’re not used for environmental surveillance. Saliva and meat don’t provide the population-wide signal that wastewater does, so they aren’t the chosen environmental sample for this purpose.