A 21-year-old white female was admitted to Charity Hospital of Louisiana on Oct. 23, 1959, with a diagnosis of "meningitis." The patient was 7 months pregnant (gravida 6, para 5). She had been in good health until 7 days prior to admission, when she developed a generalized headache, malaise, and a low-grade fever. Her physician felt that she had "flu" and treated her with tetracycline, 250 mg. every 6 hours. Two days later she developed projectile vomiting without nausea. At this time she was admitted to a private hospital and treated with intravenous fluids and "shots." Three days before admission, her speech became slurred and indistinct, and she exhibited confusion, restlessness, and athetoid movements of the right hand. She also developed marked injection of the eonjunctivae associated with inability to close her eyelids. Laboratory examination at that time disclosed: hematocrit, 37 mm.; white blood cells, 12,650 per cubic millimeter; neutrophils, 67 per cent; basophils, 1 per cent; monocytes, 2 per cent; and lymphocytes, 30 per cent. A spinal tap revealed an opening pressure of 180 mm. of water. The fluid contained 211 white blood cells per cubic millimeter with a differen¬ tial count of 60 per cent lymphocytes and 40 per cent neutrophils. The cerebrospinal fluid protein was 90 mg. per cent.The patient was transferred to the Contagious Disease Unit of Charity Hospital, where it was learned that she lived in rural Louisiana, near a swamp and bayou. Rats had been seen in the vicinity. There was an outdoor privy as well as an indoor toilet. Drinking water was obtained from the purified city system. There had been no contacts with individuals known to be ill, and her past medical history was essentially negative.Physical examination revealed a well-developed, wellnourished, pregnant, white female who was acutely ill, restless, irritable, and mentally dull. Blood pressure level was 110/70 mm. Hg; pulse, 96 beats per minute; respira¬ tions, 24 per minute. The oral temperature was 98°F.(36.7°C. ). Both eyelids were held partially open and could not be closed voluntarily. There was marked injection of the conjunctivae. The eyes tended to remain in an upward gaze, but the patient could voluntarily move them to a central position. However, attempts to deviate the eyes laterally resulted in coarse, jerking, nystagmoid movements. The pupils were equal and reacted to light. The fundi could not be examined adequately due to the patient's inability to cooperate. There was moderate pharyngeal injection without exúdate. Slight nuchal rigidity was pres¬ ent. The speech was slurred and indistinct. The liver and spleen were not palpable, but the uterus was enlarged to 2M¡ finger breadths above the umbilicus. Fetal heart tones at 140 beats per minute were audible in the left lower quadrant. Neurological abnormalities included bilateral Babinski responses and absence of the biceps, triceps, supinator, and abdominal reflexes. The ankle jerks were present, and knee jerks were hyperactive bilaterally. There was no impairment of sens...