Which of the following is a viral disease caused by one of the smallest human viruses that infects the motor cells of the anterior horn of the spinal cord?

Appeared in: JSSH Staff Nurse - 2019

Explanation

Poliomyelitis is caused by the Poliovirus, a member of the Picornaviridae family. The prefix 'pico-' signifies 'small', and these are among the smallest RNA viruses.
The virus exhibits specific neurotropism, meaning it selectively targets nerve cells.
Its primary target is the motor neurons located in the anterior horn of the spinal cord's gray matter.
Destruction of these motor neurons leads to the characteristic clinical sign of asymmetric acute flaccid paralysis without sensory loss.

Option B: Rubeola (measles) is caused by a Paramyxovirus, which is significantly larger than a Picornavirus. It primarily affects the respiratory system and skin, and while it can cause neurological complications like encephalitis, it does not specifically target the anterior horn motor cells.
Option C: Rubella is caused by a Togavirus, which is also larger than a Picornavirus. Its main clinical features are a rash and lymphadenopathy. Its major significance is the risk of congenital rubella syndrome if infection occurs during pregnancy.
Option D: Chickenpox is caused by the Varicella-Zoster Virus, a large DNA virus from the Herpesviridae family. It causes a vesicular skin rash and notably becomes latent in the dorsal root ganglia, which contain sensory neurons, not the anterior horn motor neurons.

Clinical Relevance

Nursing practice connection: Knowing Pathophysiology and virology of Poliomyelitis helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
A nurse's primary role in combating polio is through prevention via immunization campaigns and patient education on vaccine importance and schedules.
Early recognition and reporting of any case of Acute Flaccid Paralysis (AFP) is a critical public health function for nurses, initiating surveillance protocols to rule out polio and prevent potential outbreaks.
During an active infection, nurses must implement strict infection control measures (contact precautions) and provide supportive care, including monitoring respiratory function, as bulbar polio can lead to respiratory failure.

How to Approach the Question

First, dissect the question into its key components: 1) viral disease, 2) caused by a very small virus, and 3) infects motor cells in the anterior horn of the spinal cord.
Evaluate each option against these three specific criteria.
Recall or deduce the causative agent for each disease. Poliomyelitis is from Poliovirus, Rubeola from Measles virus, Rubella from Rubella virus, and Chickenpox from Varicella-Zoster virus.
Consider the virus families and relative sizes. Poliovirus is a Picornavirus ('pico' = small). Measles is a Paramyxovirus (larger), and Chickenpox is a Herpesvirus (very large). This helps narrow down the options based on the 'smallest virus' clue.
Focus on the most specific clue: the target site. The question specifies 'motor cells of the anterior horn'. Only poliomyelitis has this classic and defining pathology.
Eliminate the other options based on their primary target sites: Rubeola (respiratory/skin), Rubella (lymph/skin), and Chickenpox (skin/sensory ganglia).

Concept Tested & Keywords

Concept Tested: Pathophysiology and virology of Poliomyelitis
Stem keywords: viral disease, smallest human viruses, motor cells, anterior horn, spinal cord
Lead-in keywords: Which of the following

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Attempt every question from this paper in a timed mock, then review the full solution for each one.