Environmental surveillance for poliovirus in sewage (Environmental Surveillance — ES) as part of India's Polio Eradication Program detects poliovirus in wastewater. The MOST appropriate next step is:

• A Declare polio outbreak and initiate outbreak response immunization immediately
• B Sequencing to determine if vaccine-derived (VDPV) or wild poliovirus, and intensify AFP surveillance ✓
• C Switch from bOPV to mOPV2 without further investigation
• D No action needed as environmental detection is routine

Explanation

Detection of poliovirus in environmental surveillance requires immediate sequencing to characterize the virus as wild poliovirus (WPV) or vaccine-derived poliovirus (VDPV — requiring >1% genome divergence from parent strain). Simultaneously, Acute Flaccid Paralysis (AFP) surveillance is intensified in the catchment area to detect any paralytic cases. The response is tailored based on the type: WPV triggers outbreak response; circulating VDPV triggers targeted mOPV2 immunization.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.