Causative organism of infectious mononucleosis is:

AIIMS Nagpur NO- 2020

Applied Microbiology & Infection control

Easy

Appeared in: AIIMS Nagpur NO- 2020

Explanation

Infectious mononucleosis, also known as 'glandular fever' or the 'kissing disease,' is primarily caused by the Epstein-Barr virus (EBV).
EBV is a member of the Herpesviridae family and is one of the most common human viruses, infecting over 90% of adults worldwide.
The virus is transmitted through saliva and infects B lymphocytes, leading to the classic triad of symptoms: fever, pharyngitis (sore throat), and lymphadenopathy (swollen lymph nodes).
Diagnosis is confirmed by the presence of atypical lymphocytes on a blood smear and positive serologic tests for EBV-specific antibodies.

Option A: Cytomegalovirus (CMV) can cause a mononucleosis-like illness, especially in immunocompromised individuals, but it is a distinct entity from classic infectious mononucleosis caused by EBV. It is a common cause of 'heterophile-negative' mononucleosis.
Option B: Toxoplasma is a protozoan parasite (Toxoplasma gondii), not a virus. It causes toxoplasmosis, which can present with some similar symptoms like swollen lymph nodes, but it is a different disease with a different mode of transmission (e.g., undercooked meat, cat feces).
Option D: Varicella-zoster virus is another member of the herpesvirus family, but it is responsible for causing chickenpox (varicella) and shingles (herpes zoster). These diseases are primarily characterized by a vesicular skin rash, not the symptoms of mononucleosis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of Infectious Mononucleosis as background academic context rather than a clinical decision trigger.
Nurses play a key role in educating patients with mononucleosis about the importance of rest, hydration, and symptom management (e.g., gargling with salt water for sore throat).
A critical patient safety instruction is to avoid contact sports and strenuous activities for at least 3-4 weeks to prevent splenic rupture, a rare but life-threatening complication of splenomegaly.
What if? If a patient with confirmed mononucleosis suddenly develops sharp, severe pain in the upper left abdomen, the nurse must recognize this as a potential sign of splenic rupture and initiate emergency medical protocols immediately.

How to Approach the Question

First, identify the core of the question, which is to name the causative organism for a specific disease: 'infectious mononucleosis'.
This is a factual recall question common in microbiology. Access your knowledge base about common pathogens and the diseases they cause.
Evaluate each option. Epstein-Barr virus is classically and most commonly linked to infectious mononucleosis.
Consider the other options to confirm your choice. CMV causes a similar illness but isn't the primary cause. Toxoplasma is a parasite, and Varicella-zoster causes chickenpox/shingles. This process of elimination confirms the correct answer.

Concept Tested & Keywords

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