H. flu meningitis

Alternative names

H. influenzae meningitis; Meningitis - H. influenzae

Definition

Haemophilus influenzae meningitis is an infection of the membranes covering the brain and spinal cord (meninges) caused by H. influenzae bacteria.

Causes, incidence, and risk factors

Haemophilus influenzae type B (Hib) is a type of bacteria, not to be confused with the disease influenza, a lung infection caused by a virus.

Prior to the availability of the Hib immunization, H. influenzae 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.

In the U.S., routine Hib immunization has made H. influenzae meningitis much less common.H. influenzae meningitis may follow an upper respiratory infection and may develop slowly or rapidly. 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.

Since the introduction of the vaccine in the U.S., H. influenzae now occurs in less than 2 in 100,000 children.

Risk factors include a recent history of otitis media (ear infection), sinusitis (infection of sinuses), pharyngitis (sore throat), or other upper respiratory infection or a history of a family members with an H. influenzae infection. Another significant risk factor includes race - Native Americans have a rate of more than 3 times that of the general population. Placement in day care also increases risk.

Symptoms

• Irritability, poor feeding in infants
  
• Fever (in young infants the temperature may actually be below normal)
  
• Severe headache (older children)
  
• Nausea and vomiting
  
• Stiff neck or pain in neck when flexed
  
• Pain in back when neck is flexed foreward and chin brought toward chest (older children)
  
• Unusual body posturing
  
• Sensitivity to light
  

Signs and tests

• Bulging of the fontanelles (the soft spots on an infant's head)
  
• Opisthotonos (lying with the back arched, head, back, and chin up)
  
• Seizures
  
• Poor circulation
  
• Mental status changes (irritability, stupor, coma)