Polio is the primary infection site of?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Microbiology

Medium

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Explanation

Poliovirus is classified as an enterovirus, with 'entero-' referring to the intestines, transmitted via the fecal-oral route.
Its primary site of replication is the gastrointestinal (GI) tract, specifically the mucosa of the tonsils and the small intestine (Peyer's patches).
The virus first establishes infection and multiplies in the gut before potentially spreading to other parts of the body.
Invasion of the Central Nervous System (CNS) is a secondary, and relatively rare, complication that occurs only after the virus spreads from the gut into the bloodstream (viremia).

Option A: The urinary system is not involved in the typical pathogenesis of poliovirus infection.
Option B: While initial replication can occur in the pharynx (part of the upper respiratory and GI tracts), the main site of multiplication is the intestine, and the primary transmission route is fecal-oral, not respiratory.
Option D: This is the most common misconception. The CNS is the site of the most severe symptoms (paralysis), but it is a secondary target of the infection, not the primary one. The virus must infect the gut first.

Clinical Relevance

Nursing practice connection: Knowing Primary site of Poliovirus infection helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding that polio is primarily a GI infection is crucial for public health nurses teaching about sanitation, hand hygiene, and safe water to prevent fecal-oral transmission.
This knowledge explains the different roles of the two polio vaccines. The Oral Polio Vaccine (OPV) is critical for eradicating the virus because it induces gut immunity (IgA), preventing viral replication and shedding, thus breaking the chain of transmission.
A nurse administering the Inactivated Polio Vaccine (IPV) must understand that while it protects the individual from paralysis, the person can still carry and transmit the virus asymptomatically because IPV does not provide robust gut immunity.

How to Approach the Question

First, identify the keywords in the question: 'Polio' and 'primary infection site'. The word 'primary' is critical.
Recall the classification of Poliovirus. It is an 'enterovirus,' a major clue that it relates to the gastrointestinal ('entero-') tract.
Differentiate between the initial site of infection/replication and the site where the most severe symptoms manifest. Many diseases have different primary and secondary sites.
Evaluate the options based on this differentiation. The Central Nervous System (CNS) is where paralysis occurs, but this is a secondary complication. The Gastrointestinal (GI) system is where the virus first enters and multiplies.
Therefore, select the GI system as the primary site of infection.

Concept Tested & Keywords

QBZMzqf5Jcaa7OM8E0Sbot

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1977-1979