Incidence

Meningitis may be caused by a variety of infectious agents but is most commonly caused by viruses. It is difficult to determine how many cases of viral meningitis occur as people with mild cases of the disease may not need any medical assistance, so cases go unreported. However, bacterial meningitis is much more dangerous than viral meningitis and so is often regarded as the most important form of the disease. The causes of bacterial meningitis vary depending on the age of the person affected. In infants and young children, Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b (now rare in areas with routine Hib vaccination) are the most common meningeal pathogens. Children over 5 years of age, adolescents and adults are almost exclusively affected by Streptococcus pneumoniae and Neisseria meningitidis.

Click on the links below for more information:

• Meningococcal meningitis
  
• Pneumococcal meningitis
  
• Hib meningitis