Differential Diagnosis

1. Schizophreniform Disorder (Most Closely Competing Dx)

• Onset of psychotic symptoms is acute (< 1 month so far as of July 19)
• Prominent positive symptoms: persecutory delusions (rabies creatures chasing her, two women commanding her to kill herself and others), visual hallucinations (seeing two ugly females and small creatures)
• Total duration of illness from symptom onset to present is approximately 25 days - still within the < 6 month window
• No clear, established history of prior full manic episodes that would anchor a Bipolar I diagnosis

• The elevated, talkative, singing affect, broad affect, and "linear but sometimes tangential" thought process suggest a mood component
• Prior history of anxiety disorder, and family history of psychiatric illness

• Kaplan & Sadock's Comprehensive Textbook of Psychiatry, p. 5082

2. Schizoaffective Disorder, Bipolar Type (Strong Contender)

• Prominent psychotic symptoms (visual hallucinations of females commanding harm, persecution by "rabies creatures")
• Concurrent mood features (pressured speech suggested by singing sentences, broad affect, talkative, possibly elevated mood)
• Family history of psychiatric illness (maternal cousin)

• Swanson's Family Medicine Review, p. 764

3. Brief Psychotic Disorder (Consider, but less likely now)

• Acute and sudden onset (appeared after the cat bite and rabies fear)
• Clear precipitating stressor (fear of rabies - a marked psychosocial trigger)
• Patient was functional prior to this episode

• Duration has now exceeded 1 month (onset ~June 21, presentation July 19)
• DSM-5 requires return to premorbid functioning within 1 month; this patient has not recovered
• The episode is persisting and progressing

4. Schizophrenia (Possible but premature to diagnose)

• Prominent positive symptoms: persecutory delusions, visual hallucinations with commanding content (homicidal and suicidal)
• Family history of psychiatric illness in the maternal aunt
• Cognitive symptoms noted: transient word-finding difficulty / forgetting names

• Total duration of illness is less than 6 months (required by DSM-5 for schizophrenia diagnosis)
• Current episode is the first clear psychotic episode; longitudinal course is not yet established
• Mood features are prominent

• Kaplan & Sadock's Comprehensive Textbook of Psychiatry, p. 5082: "Young patients with bipolar disorder might seem psychotic and disorganized and, thus, schizophrenic... the clinician should place greater emphasis on the pattern of symptoms than on individual symptoms in the differential diagnosis of mood and schizophrenic psychoses."

5. Substance/Medication-Induced Psychotic Disorder (Low likelihood, but must exclude)

• Olanzapine 10 mg OD was started July 1 - though olanzapine is an antipsychotic, rarely paradoxical reactions occur
• Sertraline (SSRI) can precipitate or worsen mania/psychosis in susceptible individuals, especially in undiagnosed bipolar disorder - "antidepressant-induced manic switch"
• Biperiden (anticholinergic) was added July 4 and can cause confusion, visual hallucinations, and agitation at high doses

6. Psychotic Disorder Due to a General Medical Condition (Must Actively Exclude)

• Acute onset psychosis in a previously (largely) functioning young woman
• The original precipitant was a cat bite with fear of rabies
• Though she received anti-rabies vaccination promptly (3 doses, booster due), rabies encephalitis - while unlikely given the vaccine - must be considered
• CNS infection (encephalitis, autoimmune encephalitis such as Anti-NMDA receptor encephalitis) can present with acute psychosis, visual hallucinations, abnormal movements, and autonomic symptoms (the palpitations and warm sensation on June 24 fit this profile)

• Young female patient (peak demographic)
• Acute behavioral/psychiatric onset (psychosis, command hallucinations)
• Involuntary movements (orofacial dyskinesias - mouth deviation, hand jerky movements noted July 4)
• Cognitive changes (transient memory lapses - forgetting names)
• Autonomic instability (palpitations, temperature sensation, tachycardia episode on June 24)

7. Delusional Disorder (Less likely)

• Persecutory delusions are prominent and fixed ("rabies is trying to kill me," creatures chasing her)

• Patient has prominent hallucinations (visual), which are not typical of delusional disorder
• There are mood symptoms (broad affect, talkative, singing)
• Behavior is significantly disorganized

8. Culture-Bound / Dissociative Disorder with Cultural Framing (Contextual consideration)

• The patient sought a folk healer and a priest-exorcist before psychiatric care
• She sees "two ugly females" only in her home commanding harm - the spatial specificity (only in the house, not outside) and the folk medicine help-seeking reflect a culturally shaped illness experience
• This does not negate a psychiatric diagnosis but influences how the patient frames and communicates her symptoms
• Cultural idioms of distress should be distinguished from frank psychotic symptoms during the MSE

Summary Table

Recommended Investigations to Narrow the Differential

1. Complete blood count, metabolic panel, thyroid function (TSH, FT4) - rule out thyroid-induced psychosis
2. Urinalysis and urine drug screen - exclude substance-induced cause
3. CT Brain / MRI Brain - rule out structural or inflammatory CNS cause
4. EEG - rule out non-convulsive status, limbic encephalitis
5. CSF analysis + Anti-NMDA receptor antibody titer (serum and CSF) - this is the single most important test to rule out autoimmune encephalitis given the involuntary movements + psychiatric presentation
6. Rabies titer (post-vaccination) - documentation that vaccination was adequate; actual rabies encephalitis is unlikely given the vaccinations but should be documented
7. Pelvic/abdominal ultrasound - Anti-NMDA receptor encephalitis in young women is often associated with ovarian teratoma; must be excluded if antibody comes back positive