Maryland Department of Health
Prevention and Health Promotion Administration

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Haemophilus influenzae type b (Hib) Disease
Fact Sheet

PDF Version of this Fact Sheet

Haemophilus influenzae type b (Hib) is a bacterium that causes serious infections.

Before the advent of effective vaccines, Hib was the most common cause of bacterial meningitis in children in the United States as well as in many other countries.  Since 1988, when the Hib vaccines were introduced, the rate of invasive Hib disease has decline by 99% in infants and young children.  When disease occurs, it usually is in children 2 months to 5 years of age.  Hib and types of Haemophilus influenzae other than type b can cause disease in elderly persons with underlying health conditions.  Hib can cause meningitis (inflammation of the brain and spinal cord covering) and other infections such as pneumonia (lung infection), ear, skin, joint, and blood infections.

Hib is spread from person-to-person by airborne droplets and direct contact with infected respiratory secretions.

Hib is carried in the nose or throat of children and adults who are infected.  It is possible for people who are not ill to carry Hib and spread it to others.  It is then spread to the next person through contact with discharge or droplets from the nose or mouth. 

Symptoms to look for include:

  • Meningitis
  • Fever
  • Stiff neck
  • Drowsiness
  • Extreme irritability
  • Sudden vomiting
  • Other Hib infections
  • Symptoms at site of infection (for example: skin or joint redness, tenderness, or swollen area)

The time period between when someone is exposed to Hib and when symptoms develop is unknown, but may be as short as 2 to 4 days.

Laboratory testing is available to confirm a Hib infection. 

People who think they may have Hib disease should see a doctor or their local health department.  Hib disease is diagnosed by testing the blood, spinal fluid, middle ear, and other bodily fluids.  See a doctor immediately for treatment.

Treatment with antibiotics should be started immediately to stop the infection from causing serious complications or death.

Certain people in close contact with someone who has Hib disease should receive treatment as well. 
In specific situations, such as childcare settings, people who have been exposed to someone with Hib may be given a drug called rifampin to prevent getting or spreading Hib.  Rifampin is not recommended for pregnant women.  High risk contacts include: 

  • Persons who are 4 years of age and younger who are unimmunized or incompletely immunized;
  • Children younger than 12 months of age who have not received the primary series of vaccine
  • ; or
  • Immunocom
  • promised children regardless of the child’s Hib immunization status. 

Hib disease can be prevented with Hib vaccine.

Hib vaccine is recommended for all children starting at 2, 4, 6 and 15 months of age.  Hib vaccine is recommended for all children under 5 years of age who have not been previously immunized, and others may need Hib vaccine if they are at an increased risk for disease.  Age appropriate vaccination against Hib is required for entry into Maryland childcare institutions and schools. For additional information about Hib vaccine, please visit: http://www.cdc.gov/vaccines/vpd-vac/hib/default.htm.