BACTERIAL INFECTIONS of the nervous system caused by HAEMOPHILUS organisms, and marked by prominent inflammation of the meninges. HAEMOPHILUS INFLUENZAE TYPE B is the most common causative organism. The condition primarily affects children under 6 years of age but may occur in adults. Clinical manifestations include fever; nuchal rigidity; PHOTOPHOBIA; SEIZURES; HEARING LOSS, SENSORINEURAL; COMA; and cerebrovascular thrombosis. The organism tends to enter the central nervous system following infections of adjacent structures, including the middle ear (see also OTITIS MEDIA), sinuses, and pharynx. (From Menkes, Textbook of Child Neurology, 5th ed, pp396-7).