Why is stool sample testing particularly important in suspected poliomyelitis?

• A. Because stool samples are easy to collect.
• B. Because poliovirus replicates and is shed in stool; stool testing confirms infection and helps type the strain.
• C. Because blood tests for poliovirus are always unreliable.
• D. Because stool testing detects immunity levels.

Answer: (B)

Poliovirus replicates in the gut and is shed in stool during acute infection, so stool testing directly detects the virus when someone is infected and provides the clearest confirmation of poliomyelitis. Testing stool allows not only to confirm infection but also to identify the specific strain, which is essential for distinguishing wild-type virus from vaccine-derived strains and for surveillance and outbreak response. Blood tests don’t reliably diagnose acute poliovirus infection because viremia is transient and antibody tests reflect immunity rather than current infection. Stool testing focuses on detecting the virus itself, not measuring immunity levels.