Inflammation of the membrane surrounding the brain, usually caused by viruses or bacteria, sometimes however by a fungus or parasites. The condition often occurs rapidly, after influenza, otitis or pharyngitis. After some days the patient complains of headache and fever, often with nausea and vomiting; consciousness is sometimes lowered. Irritation of the membranes causes a stiff neck. In babies the condition shows in general malaise and nausea and a fontanel which is tense to the touch. Meningeal irritation results in pain if the child’s legs are manipulated. The most notorious bacterium is the highly infectious meninogococcus Neisseria meningitidis. Groups of people living in crowded conditions -soldiers, for example – are prone to epidemics of this form of meningitis. After a short period in which the patient feels unwell, he complains of sudden severe headache, fever with vomiting, and severe neck cramp. The patient is confused, and consciousness can be lowered to a state of coma. Complications are shock (through a general disturbance in blood supply), epilepsy and increased pressure on the brain caused by reduced drainage of cerebral fluid. Children may suffer from hydrocephalus. Examination of the cerebral fluid can establish whether the inflammation is viral or bacterial. Viral inflammation clears up without treatment within 1 to 2 weeks. With bacterial infection, the correct antibiotics must be administered