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A 25-year-old man is brought to the emergency department by his partner following an episode of generalized convulsions. His partner reports that for the past 3 days, the patient has had a high fever and severe headache accompanied by nausea and vomiting. She also mentions that he started complaining of smell and taste changes. A few days ago, they came back from a trip to California in which they hiked and swam in lakes. Temperature is 38.9°C (102°F), pulse is 80/min, and blood pressure is 135/85 mmHg. On physical examination, the patient is confused and unresponsive. Pupils are equal and react sluggishly to light. Brudzinski sign is positive. A lumbar puncture is performed, and cerebrospinal fluid (CSF) analysis shows the following:  

 Cerebrospinal fluid 
 Opening pressure  300 mm H2
 Protein   130 mg/dL 
 Glucose  20 mg/dL 
 RBCs  Numerous 
 WBC count   1500/µL with polymorphonuclear predominance 
 Neutrophils   80%  

Gram stain of the CSF is negative. Head imaging results are nonspecific. Which of the following is the most likely causative organism?

Memory Anchors and Partner Content

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Anti-NMDA receptor encephalitis p. 221


anti-NMDA receptor p. 221

Cryptococcus neoformans p. , 150

cytomegalovirus p. 174

guanosine analogs p. 199

herpesviruses p. 161, 177

HIV-positive adults p. 174

HSV identification p. 163

Lassa fever p. 164

neonatal p. 181

rubeola p. 167

small cell lung cancer p. 709

togaviruses p. 164

West Nile virus p. 177

Herpes simplex virus 1 (HSV-1) p. 161

encephalitis p. 731

Lassa fever encephalitis p. 164

Memory loss

anti-NMDA receptor encephalitis p. 221

Seizures p. 535

anti-NMDA receptor encephalitis p. 221

Temporal lobe encephalitis p. 161


Encephalitis is an acute inflammation of the brain. It can be caused by a viral, bacterial, or parasitic infection, or it can be a result of autoimmune disorders. Symptoms include fever, headache, nausea, vomiting, and fatigue. In some cases, encephalitis can lead to seizures, coma, and death.


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