Definition
Meningitis is inflammation of the meninges, the protective membranes covering the brain and spinal cord.
- It can be caused by infections or, less commonly, by non-infectious conditions.
- It is a medical emergency, especially when caused by bacteria.
Causes
Bacterial Meningitis
- Caused by bacteria such as Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae.
- Rapid onset and potentially life-threatening.
- Requires urgent antibiotic treatment.
Viral Meningitis
- Most commonly caused by enteroviruses.
- Usually milder than bacterial meningitis.
- Often self-limiting.
Other Causes
- Fungal infections.
- Tuberculosis.
- Certain medications.
- Autoimmune disorders.
Pathophysiology
- Pathogens enter bloodstream and cross the blood–brain barrier.
- Inflammation of meninges leads to increased intracranial pressure.
- Release of inflammatory mediators contributes to neurological damage.
Clinical Features
Common symptoms include:
- High fever.
- Severe headache.
- Neck stiffness.
- Sensitivity to light.
- Altered consciousness.
In infants:
- Bulging fontanelle.
- Irritability.
- Poor feeding.
In meningococcal infection, a characteristic purpuric or petechial rash may appear.
Diagnosis
- Lumbar puncture to analyse cerebrospinal fluid.
- Blood cultures.
- Polymerase chain reaction tests.
- Imaging in selected cases.
CSF findings help distinguish bacterial from viral causes.
Treatment
Bacterial Meningitis
- Immediate intravenous antibiotics.
- Corticosteroids may reduce complications.
- Intensive supportive care in severe cases.
Viral Meningitis
- Supportive treatment.
- Antiviral therapy in selected viral causes.
Early treatment significantly reduces mortality and long-term complications.
Complications
- Hearing loss.
- Seizures.
- Brain damage.
- Cognitive impairment.
- Septic shock in severe cases.
Prevention
Vaccination
Vaccines available against major bacterial causes:
- Meningococcal vaccines.
- Pneumococcal vaccines.
- Haemophilus influenzae type b vaccine.
Public Health Measures
- Chemoprophylaxis for close contacts.
- Surveillance during outbreaks.
Public Health Significance
- Major cause of morbidity and mortality worldwide.
- Can lead to outbreaks and epidemics.
- Rapid progression makes early diagnosis and prevention critical.
Meningitis is a serious inflammatory condition of the central nervous system requiring prompt recognition, rapid medical intervention and strong vaccination strategies to reduce its public health burden.
