Meningitis and Encephalitis

Meningitis is caused by bacteria and viruses, which can infect and cause inflammation of the membranes covering the brain (the meninges); the common bacteria are the Haemophilus influenza, pneumococcus and meningococus. The disease, which is a serious infection, occurs at all ages of life, but it is commoner in infancy and childhood. H.influenza infection is the most dangerous, as it is responsible for serious complications such as collections of fluid ( effusion ) or pus ( abscess ) in the surrounding area ( subdural effusion or abscess ); it is also the commonest. it can be prevented by the HiB vaccine given in infancy. ln most cases of meningitis, the symptoms occur fairly suddenly; this is called acute meningitis. However, a more gradual onset occurs intuberculous meningitis, which is a serious form of tuberculosis. Acute meningitis is often preceded by a “flu-like” illness. Within a day or two, the fever rises and there is severe headache, vomiting, and a stiff neck; very often patients are over- sensitive to light. ln babies and small children, however, the presenting features are often excessive crying, irritability, fits, drowsiness, and failure to suck. ln babies a bulging anterior fontanelle is an early sign. In older children and adults there is a rigidity of the neck muscles, and an inability to straighten the leg when it is bent at the hip (Kernig's sign). ln meningitis due to the meningococus there may be a rash of large red spots. ln the subacute and chronic forms these symptoms develop gradually. 

The doctor would do blood tests, and a lumbar puncture to examine the cerebro-spinal fluid. These tests would help in making the diagnosis, and in finding out the causative organism. Treatment has to be initiated very early with high doses of the appropdate antibiotic, when bacteria cause meningitis unlike in the preantibiotic era, most cases of bacterial meningitis are now curable; most patients reoover completely. ln a few patients,especially in the newborns, there may be residual complications such as deafness, mental retardation and other neurological damage. 

Encephalitis

Encephalitis is an inflammation of the brain substance, usually caused by viruses one such virus is the Japanese B virus. Other viruses are those causing herpes, chicken pox, mumps, measles and rabies. lt may also be caused by the malaria parasite (falciparum); this is known as cerebral malaria. lt can also occur as an allergic reaction, or it may be due to poisons such as lead. In such instances, the disease is referred to as encephalopathy. 

The clinical features are similar to that of meningitis. Most patients recover completely. Some patients may remain unconscious for many days, sometimes even as long as hundred days. During this period of unconsciousness, certain sensations may be perceived. It is therefore very necessary that persons especially those very close to the patient, such as parent, spouse, or sibling should keep on talking to them; or perhaps singing to them, or providing music, which they were known to appreciate. Residual defects such as partial deafness, partial blindness, mental retardation, paralysis or other neurological damage may occur; but several patients are known to make a complete recovery.