The concept of 'poliovirus environmental surveillance' (sewage surveillance) detects poliovirus in wastewater before clinical cases appear. The critical advantage of this approach over AFP (Acute Flaccid Paralysis) surveillance is:
- A It is cheaper and does not require trained field workers
- B It detects virus circulation before paralytic cases occur, enabling preemptive response ✓
- C It specifically distinguishes wild poliovirus from vaccine-derived poliovirus (VDPV)
- D AFP surveillance captures only children aged 0–5 years, while sewage covers all ages
Explanation
For every paralytic polio case, approximately 200 asymptomatic infections occur; thus AFP surveillance misses the vast majority of virus circulation. Environmental surveillance of sewage detects excreted poliovirus from both symptomatic and asymptomatic individuals, providing an early warning system for poliovirus importation or circulation before clinical paralysis manifests. Both wild poliovirus and VDPV can be detected and differentiated by molecular sequencing, but this is a secondary benefit; the primary advantage is early detection before clinical disease.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.