St. Louis encephalitis with focal neurological signs.

St. Louis encephalitis (SLE) is a form of epidemic encephalitis named for a 1993 outbreak in that Missouri city when 11000 cases occurred; the fatality rate during this epidemic was ∼20% [1]. Although it is the most common type of viral encephalitis, !1% of patients present for medical attention [2]. Symptoms are usually nonspecific and consistent with those of viral meningitis. The virus causing SLE is distributed throughout the United States, and similar viruses exist worldwide. The disease is spread by Culex species mosquitoes, hence the primary risk factor is mosquito exposure. Focal neurological signs are extraordinary: to our knowledge, there are no previous reports of SLE with focal neurological signs in the medical literature. Here we report the case of a young man who presented with delirium and focal neurological signs attributable to SLE. A 33-year-old man was admitted to the hospital with weakness and delirium. Two days before admission, the patient complained only of dizziness. On the day before admission, he had a right footdrop. He was seen at an emergency department and was discharged. He woke up the next morning with right lower extremity paralysis and was admitted to another institution. The patient had no significant medical history and had not traveled for several months from northern Louisiana. He regularly abused alcohol and occasionally abused illicit (not intravenous) drugs. His temperature was 38.47C. He was anxious and agitated but cooperative. The right lower extremity strength was graded 1/5 with areflexia; the left lower extremity strength was graded 2/5 with hyporeflexia. The remainder of the physical examination was unremarkable. Pertinent findings included a negative urine toxicology screen, and the serum chemistry analysis was normal. Lumbar puncture revealed CSF with a WBC count of 484/mm (75% lymphocytes, 23% polymorphonuclear cells, and 2% monocytes), an RBC count of 21/mm, a glucose level of 48 mg/dL, and a protein level of 87 mg/dL. CT of the head and spine with contrast medium was unremarkable. On hospital day 2, the patient became delirious. Thereafter, his condition was stable for 10 days, and he was transferred to our hospital. At that time, all cultures and an ELISA for HIV were negative. At our institution, his mental status varied. The right lower extremity was paralyzed with areflexia; the left leg had 2/5 strength with hyporeflexia. Results of the remainder of the physical examination were normal. Magnetic resonance imaging of the head and spine with contrast medium was unre-