Which of the following is/are clinical features of tetanus?
**Core Concept**
Tetanus is a bacterial infection caused by Clostridium tetani, which produces a potent neurotoxin that affects the nervous system, leading to a range of clinical manifestations.
**Why the Correct Answer is Right**
The clinical features of tetanus are primarily due to the action of tetanospasmin, the neurotoxin produced by C. tetani. Tetanospasmin blocks the release of neurotransmitters glycine and GABA, leading to an increase in muscle tone and spasms. The toxin also affects the autonomic nervous system, resulting in symptoms such as rigidity, spasms, and autonomic instability. The incubation period of tetanus is typically between 3-21 days, during which the patient may experience mild symptoms such as muscle stiffness and pain.
**Why Each Wrong Option is Incorrect**
* **Option A:** Trismus (lockjaw) is a classic symptom of tetanus, but it is not the only clinical feature. Trismus is caused by tetanospasmin-induced spasms of the masseter muscle.
* **Option B:** Diarrhea is not a typical symptom of tetanus. In fact, constipation is a more common gastrointestinal symptom due to autonomic nervous system dysfunction.
* **Option C:** Fever is not a characteristic symptom of tetanus. The infection is typically aseptic, meaning it does not cause a significant inflammatory response or fever.
**Clinical Pearl / High-Yield Fact**
Tetanus is often referred to as a "100% mortality rate in the absence of treatment" because of its high mortality rate if left untreated. However, with proper wound care and administration of tetanus immune globulin (TIG) and tetanus toxoid, the mortality rate can be significantly reduced.
**Correct Answer: A. Trismus (lockjaw).**