What type of sample can be used to isolate polio virus?

MP CHO - 2022

Applied Microbiology & Infection control

Easy

Appeared in: MP CHO - 2022

Explanation

Stool is the correct sample because poliovirus is an enterovirus that replicates extensively in the gastrointestinal tract.
The virus is shed in high concentrations in the feces for several weeks, making stool the most reliable specimen for isolation and diagnosis.
The World Health Organization (WHO) recommends collecting two stool specimens 24-48 hours apart, within 14 days of paralysis onset, for AFP surveillance.
Virus isolation from stool has the highest success rate compared to other sample types.

Option B: While poliovirus can be isolated from the throat, it is only present for a short period (the first 3-5 days of illness). Viral shedding from the throat is much less prolonged and consistent than from the stool, making it a less reliable sample for diagnosis.
Option C: Poliovirus is rarely isolated from the cerebrospinal fluid (CSF). Although patients with paralytic polio have CNS involvement, the virus itself is not typically found in the CSF.
Option D: The viremic phase (presence of virus in the blood) of poliovirus infection is very transient and occurs before the onset of major symptoms. By the time a patient presents with paralysis, the virus is typically no longer detectable in the blood.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Specimen collection for Poliovirus isolation as background academic context rather than a clinical decision trigger.
Accurate and timely sample collection is critical for the Global Polio Eradication Initiative's surveillance of Acute Flaccid Paralysis (AFP). Identifying poliovirus confirms the diagnosis and helps public health officials track outbreaks and circulation.
Nurses play a key role in educating patients and families on the proper procedure for collecting stool samples, ensuring a clean, non-contaminated specimen of adequate quantity (8-10 grams) is collected.
Maintaining the cold chain (transporting the sample at 2-8°C) is essential to preserve the viability of the virus until it reaches the laboratory for analysis.

How to Approach the Question

First, identify the core of the question: it asks for the best sample to 'isolate' the 'polio virus'.
Recall the nature of poliovirus. It is an 'enterovirus', which is a major clue. 'Entero-' refers to the intestines.
Based on its classification as an enterovirus, deduce that its primary site of replication and shedding is the gastrointestinal tract.
Therefore, the sample most likely to contain a high and sustained concentration of the virus would be from the GI tract, which is stool.
Evaluate the other options: Throat (transient shedding), CSF (rarely positive), and Blood (transient viremia) are all less optimal for isolation compared to stool.

Concept Tested & Keywords

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