Questions & Answers
Haemophilus B - The Disease
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  1. What is Haemophilus Type B disease?

    Haemophilus type b disease is caused by bacteria called Haemophilus influenzae type b, or Hib for short. Sometimes it’s called “H. flu.”

    There are six different types of this bacteria: a through f. Type b organisms account for 95% of all strains that cause serious Hib disease, and this is the type against which the Hib vaccine protects.

  2. How common is Hib disease in the United States?
    Before the introduction of a Hib vaccine, H. influenzae type b (Hib) was the leading cause of bacterial meningitis among children under five years old in the United States. Every year about 20,000 children under five got severe Hib disease and about 1,000 individuals died. More than half of children who developed severe Hib disease were less than 12 months of age. Since 1988, when a Hib vaccine was first introduced, the rate of Hib disease has decreased more than 99%. From 1996 through 2000, an average of about 70 children per year were reported with Hib disease.

  3. Can you get Hib disease more than once?
    Yes. A child with Hib disease may not develop protective levels of antibodies. Children less than 24 months of age who have recovered from invasive Hib disease should be considered unimmunized and receive the Hib vaccine as soon as possible.

  4. How does Hib disease spread?
    Hib disease is spread from person-to-person by direct contact or through respiratory droplets. It is not highly contagious. Usually the organisms remain in the nose and throat, but occasionally the bacteria spread to the lungs or bloodstream and cause a serious invasive disease in the infected individual.

  5. How long does it take to show signs of Hib disease after being exposed?
    The incubation period of Hib disease is unknown, but could be as short as a few days.


  1. What are the symptoms of Hib disease?
    A person with invasive Hib disease can have different symptoms depending on what body systems are affected. See next question.

  2. How serious is Hib disease?
    Hib disease can be very serious. The most common type of serious Hib disease is meningitis, an infection of the membranes covering the brain (from 50% to 65% of cases). Symptoms of Hib meningitis are fever, severe headache, decreased mental status, and stiff neck. The mortality rate is 2% to 5%. In addition, 15% to 30% of survivors suffer some permanent neurologic damage, including blindness, deafness, and mental retardation. Another 17% of serious Hib cases include epiglottitis, an infection and swelling in the throat that can cause life-threatening airway blockage. Other symptoms of invasive Hib disease include: pneumonia (15%), joint infection (8%), skin infection (6%), and bone infection (2%).


  1. How do I know if my child has Hib disease?
    The diagnosis of Hib disease is usually made based on one or more laboratory tests using a sample of infected body fluid, such as blood or spinal fluid.

  2. Is there a treatment for Hib disease?
    Hib disease is treated with antibiotics for 10 to 14 days. Most cases require hospitalization. Even with antibiotic treatment, about 5% of all children with Hib meningitis die from the disease.