**Question:** Select the true statement regarding Tetanus

A. Tetanus is caused by a bacterium, Clostridium tetani, which produces a neurotoxin that affects skeletal muscles.
B. Tetanus is a vaccine-preventable disease.
C. Tetanus primarily affects the respiratory system.
D. The neurotoxin produced by Clostridium tetani causes muscle rigidity and spasms.

**Correct Answer: D.**

**Core Concept:** Tetanus is a serious bacterial infection caused by Clostridium tetani, which produces a neurotoxin called tetanospasmin. This toxin affects the central and peripheral nervous system, leading to muscle spasms and rigidity (tetanus), hence the name. The infection primarily affects the skeletal muscles, resulting in the characteristic spastic symptoms.

**Why the Correct Answer is Right:**

Tetanus is caused by the bacterium Clostridium tetani, which is commonly found in soil and manure. When the bacterium enters the body through a wound, it produces tetanospasmin, a potent neurotoxin that interferes with the neuromuscular transmission. This toxin affects both the central and peripheral nervous system, leading to the characteristic tetanic muscle contractions known as tetanus. The neurotoxin acts on the neuromuscular junction, blocking the release of acetylcholine, a neurotransmitter that facilitates muscle contraction. This leads to the muscle spasms and rigidity seen in tetanus patients.

**Why Each Wrong Option is Incorrect:**

A. Tetanus primarily affects the respiratory system, which is incorrect because tetanus primarily affects the neuromuscular system, leading to spasms and rigidity in skeletal muscles.

C. Tetanus is a common infection, which is incorrect as tetanus is relatively rare in developed countries due to widespread vaccination programs but remains prevalent in some undeveloped regions where vaccination rates are low.

Tetanus is a vaccine-preventable disease, but many parts of the world lack access to vaccines, leading to tetanus cases.

**Clinical Pearls:**

Tetanus vaccination is highly recommended and available globally. It is crucial for preventing tetanus infections, as the disease can lead to severe complications, including respiratory distress, cardiovascular collapse, and death. Prompt tetanus prophylaxis and treatment can significantly improve the patient's prognosis. Tetanus toxin is a potent neurotoxin that targets the neuromuscular junction, causing muscle spasms and rigidity, which can lead to life-threatening complications when left untreated.