A 20 year old boy complains of hearing voices and aggressive behavior for last 2 days. He had persistent high fever before the onset of these symptoms. The family members repo that he has been muttering to self and gesticulating as if he is talking to someone. There is no history of any past psychiatric illness. The likely diagnosis is:-

**Core Concept**
The patient's symptoms of hearing voices, aggressive behavior, and muttering to self suggest a psychotic disorder, specifically a type of schizophrenia or a psychotic episode. The presence of a recent high fever and gesticulation may indicate a post-infectious or autoimmune etiology.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with a diagnosis of post-infectious or autoimmune psychosis, such as Post-Infectious Psychosis (PIP) or Autoimmune Encephalitis. The high fever preceding the onset of symptoms may have triggered an autoimmune response, leading to inflammation in the brain and the development of psychosis. This condition is often associated with abnormalities in the cerebrospinal fluid (CSF) and imaging studies, such as MRI scans, may show changes in the brain.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not take into account the patient's recent history of high fever and the presence of muttering to self, which suggests a more complex etiology than a simple mood disorder.
**Option B:** This option is incorrect because it does not consider the possibility of an autoimmune or post-infectious cause for the patient's psychosis.
**Option C:** This option is incorrect because it does not account for the patient's recent high fever and the presence of muttering to self, which are not typical features of a primary psychotic disorder.

**Clinical Pearl / High-Yield Fact**
Post-infectious psychosis can occur after a variety of infections, including viral and bacterial infections, and may be associated with abnormalities in the CSF and imaging studies. It is essential to consider this diagnosis in patients with recent fever and psychotic symptoms.

**Correct Answer:** C.

✓ Correct Answer: B. Acute psychosis