Meningitis; H. influenza:

Alternative names:

H. influenza meningitis, H. flu meningitis.

Definition:

An infection caused by H. influenza, which causes inflammation of the membranes covering the brain and spinal cord.

Causes, incidence, and risk factors:

Hemophilus influenza meningitis is caused by the organism Hemophilus influenza (not to be mistaken for the disease influenza, a respiratory illness caused by a virus). Prior to the availability of the Hib immunization Haemophilus influenza was the leading cause of bacterial meningitis in children under 5 years of age. It occurs most frequently in children from 1 month up to 4 years with a peak at 6 to 9 months then begins to decline. Routine Hib immunization has resulted in a marked decrease in the incidence of H. influenza meningitis and has proved a remarkably safe immunization with great benefit. H. flu meningitis may follow an upper respiratory infection and develop slowly or its onset may be rapid. The infections spreads usually from somewhere in the respiratory tract (often the nasopharynx) to the blood stream and ultimately to the meninges (membranes that cover the brain). On the meninges the bacteria produce infection and inflammation with profound and deadly results. Risk factors include a recent history of otitis mediasinusitispharyngitis or other upper respiratory infection, or a history of a family members with an H. influenza infection. Another significant risk factor includes race. American Indian and Eskimo have a rate over three times that of the average population. Placement in a day-care setting also increases the risk.The incidence of Hemophilus influenza is 2-to-5 out of 10,000 people.