Meningitis is a condition in which the protective membranes of the brain or meninges become inflamed. This may be due to an infection or any other factor that causes physical or chemical trauma to the membranes. Infecting organisms may be bacteria, protozoa, viruses or fungi. Whenever the meninges are inflamed, there is a risk of spinal cord or brain involvement with possible loss in neurological function. The signs and symptoms of meningitis may not be picked up very easily in the initial stages if the attending physician is not well experienced.

In the early stages of an infection, many patients may confuse the symptoms with those of the flu. It is only after it has progressed that the classical signs of meningitis become apparent. The pattern of the manifestations, therefore, greatly depends on the stage. Another important factor that determines the symptomatology is the causative factor (microorganisms or aseptic causes). Even among cases caused by organisms, there are differences.

Different age groups are susceptible to different organisms known to cause meningitis. Newborns and infants are most commonly affected by the organisms belonging to group B streptococci acquired from the birth canal at birth. Other organisms include Listeria monocytogenes and E. Coli. As they grow older, cases of Neisseria meningitidis and Haemophilus influenzae (specifically type B) become more common. Adults are most likely to be affected by Streptococcus pneumoniae.

Severe disease is characterised by systemic involvement. When microbes enter the circulation they lead to either of two conditions: septicaemia or bacteraemia. The former condition is the more serious of the two as it indicates a large quantity of organisms that are enough to infect organs. The term meningococcemia is used to refer to septicaemia caused by Neisseria meningitidis. This is one of the most serious complications and is characterised by damage to vessels and bleeding into the skin as well as other organs.

There is a classic triad of signs and symptoms used to make a diagnosis of meningitis. They include neck stiffness, altered mental status and a high fever. This combination is observed in at least 45% of affected individuals. The absence of all the three almost always rules out the disease. Neck stiffness is observed in at least 70% of the cases. In spite of being very common at 90%, headache does not make up this triad.

Other possible symptoms include drowsiness (sluggishness), excessive sensitivity to light (photophobia). There may be convulsions and subsequent coma in the more severe cases. Diagnosis is very difficult in new-borns and infants. This is because they usually present very non-specifically. They may have fever, seizures, poor feeding, irritability and lethargy. The seizures will be present in about 30% of them.

Meningococcal diseases results in distinct signs. There is often a change in colour of the skin. The colour becomes darker due to bleeding taking place underneath. There have also been reports of skin rashes, cold extremities, myalgia (muscle pain), joint pain (arthralgia), chills and increased rate of breathing.

If one experiences any of the signs and symptoms of meningitis they should call their physician immediately. This is because the condition is a medical emergency that requires prompt treatment. Some of the complications associated with lack of treatment include epilepsy, deficits in cognition hydrocephalus and hearing impairment.