A 13-year-old white female complained of a 2-month history of diffuse, often intense headaches and a 1-month history of intermittent nausea, vomiting, and anorexia with intermittent low-grade fevers. An outpatient evaluation included 2 negative rapid screens for group A streptococcus, a negative heterophil antibody test, a negative rapid influenza antigen test, and a normal gall bladder ultrasound. Symptoms persisted despite a 5-day course of azithromycin. She was hospitalized secondary to worsening headaches, nausea, and the onset of diplopia. The patient lived in a rural area in Kentucky and had multiple animal exposures. Family pets included a dog and a fish, and the patient’s home was infested with mice. Just before the onset of her symptoms, the patient had explored a deserted house and found a dead opossum, but she denied touching it. She had recently visited a local stockyard and denied direct contact with the cattle, but did have contact with cow manure; her face had been splashed with manure while she was riding an all-terrain vehicle across a cow pasture. On initial evaluation, the patient had a temperature of 36.4� C, a heart rate of 80 bpm, and blood pressure of116/57 mm Hg. Her neurologic exam was remarkable for bilateral papilledema, left esotropia, left abduction deficit, mild left upper lid ptosis, and mild gait ataxia. Respiratory, cardiovascular, joint, extremity, and lymph node examinations were normal. At admission, the white blood cell (WBC) count was 7.7 3 10 3 /mL with 59% neutrophils, 29% lymphocytes, and 9% monocytes. Hemoglobin was 13.8 gm/dL, and platelets were 371 3 10 3 /mL. Electrolytes and serum transaminases, bilirubin, and albumin were within normal limits. Antibodies to human immunodeficiency virus I and II and Borrelia burgdorferi were negative. A serum rapid plasma reagin (RPR) for syphilis was also negative. Blood and urine cultures were sterile. A tuberculin skin test was negative with positive response to a Candida control. Cerebrospinal fluid (CSF) was clear and colorless with an opening pressure of 310 mm Hg. There were 440 WBCs/mL (7% neutrophils, 80% lymphocytes, 13% monocytes) and 130 red blood cells (RBCs)/mL. CSF protein was 79 mg/dL, and glucose was 38 mg/dL. Negative CSF studies included bacterial and mycobacterial cultures, acid-fast bacilli stain, VDRL, adenovirus polymerase chain reaction, and cryptococcal antigen. Magnetic resonance imaging (MRI) of the brain with and without gadolinium at the time of admission and 5 days later demonstrated no meningeal enhancement or focal lesions. Electroencephalography and echocardiography were also normal. A chest radiograph revealed no parenchymal disease or lymphadenopathy. Cefotaxime was begun empirically, but was discontinued after 4 days. An evaluation for immunodeficiency included normal quantitative immunoglobulins (IgG, 1100 mg/dL; IgM, 172 mg/dL; IgA, not done). Peripheral blood immunotyping revealed normal percentages and absolute numbers of T and B cells with normal lymphocyte response to phytohemagglutinin stimulation.