How is poliovirus detected in environmental samples and what markers indicate circulation?

• A. Colorimetric test of water
• B. RT-PCR on sewage samples to detect PV RNA, along with successful virus isolation and sequence analysis showing lineage and divergence
• C. Measuring chlorine residuals
• D. Environmental samples cannot detect PV

Answer: (B)

The key idea is that monitoring poliovirus in the environment relies on wastewater-based surveillance using both genetic and virologic methods. The most robust evidence of circulation comes from testing sewage with RT-PCR to detect poliovirus RNA, then attempting virus isolation to see if infectious virus is present, and performing sequence analysis to identify the lineage and measure divergence. RT-PCR is highly sensitive and fast, signaling that the virus is being shed in the community. Isolating the virus confirms infectious material, which matters for understanding transmission risk. Sequencing reveals how the detected strains relate to known wild-type or vaccine-derived lineages, showing whether there has been recent transmission and how strains are evolving. Together, these steps provide a clear picture of circulation and transmission dynamics. Colorimetric tests of water and chlorine residuals don’t detect viral RNA or infectious virus, and environmental samples can indeed detect poliovirus, so those options don’t fit.