Definition of Meningitis - H. influenzae:

Haemophilus influenzae meningitis is a bacterial infection of the membranes covering the brain and spinal cord (meninges).

See also:

• Aseptic meningitis
• Meningitis
• Meningitis - cryptococcal
• Meningitis - Gram-negative
• Meningitis - meningococcal
• Meningitis - pneumococcal
• Meningitis - staphylococcal
• Meningitis - tuberculous

Causes, incidence, and risk factors:

H. influenzae meningitis is caused by Haemophilus influenzae bacteria. These bacteria should not be confused with the disease influenza, an upper respiratory infection caused by the influenza virus.

Before the Hib vaccine became available, H. influenzae was the leading cause of bacterial meningitis in children under age 5. Since the introduction of the vaccine in the U.S., H. influenzae meningitis occurs in less than 2 in 100,000 children. It still causes 5% - 10% of bacterial meningitis cases in adults.

H. influenzae meningitis may occur after an upper respiratory infection. The infection usually spreads from the respiratory tract to the bloodstream, and then to the meninges. At the meninges, the bacteria produce infection and inflammation, causing serious illness and sometimes death.

Risk factors include:

• Ear infection (otitis media)
• Family member with an H. influenzae infection
• Native American race
• Placement in day care
• Sinus infection (sinusitis)
• Sore throat (pharyngitis)
• Upper respiratory infection