Acute mesenteric lymphadenitis is caused by
**Core Concept**
Acute mesenteric lymphadenitis refers to the inflammation of the mesenteric lymph nodes, often due to viral or bacterial infections, which can cause abdominal pain, fever, and other systemic symptoms. This condition is a form of reactive lymphadenopathy, where the lymph nodes become enlarged and inflamed in response to an infectious agent.
**Why the Correct Answer is Right**
The correct answer is likely caused by a viral infection, specifically enteroviruses such as coxsackievirus or echovirus. These viruses can infect the mesenteric lymph nodes, leading to inflammation and enlargement. The exact mechanism involves the binding of the viral particles to the host cells via receptors, followed by the release of pro-inflammatory cytokines and the activation of immune cells. This results in the characteristic symptoms of acute mesenteric lymphadenitis.
**Why Each Wrong Option is Incorrect**
* **Option A:** Bacterial infections, such as Salmonella or Shigella, can cause mesenteric lymphadenitis, but they are less common causes compared to viral infections.
* **Option B:** Fungal infections, such as candidiasis, are rare causes of mesenteric lymphadenitis and typically occur in immunocompromised individuals.
* **Option D:** Tuberculosis (TB) is a possible cause of chronic mesenteric lymphadenitis, but it is not typically associated with acute presentations.
**Clinical Pearl / High-Yield Fact**
When suspecting acute mesenteric lymphadenitis, remember that enteroviral infections are a common cause, and the condition often presents with non-specific symptoms such as abdominal pain, fever, and malaise.
**Correct Answer: A. Viral infection.**