Health Information

Haemophilus Influenzae Infections

What is Haemophilus influenzae?

Haemophilus influenzae, or H. influenzae, represents a group of bacteria that may cause different types of infections in infants and children. H. influenzae most commonly causes ear, eye, or sinus infections, and pneumonia. A more serious strain of the bacteria called H. influenzae type b has been nearly abolished in the U.S. due to the development of an effective vaccine, which has been available since 1988. The more serious strain was responsible for causing many cases of meningitis (infection of the membranes that surround the brain) and a life-threatening infection called epiglottitis (infection of the area of the throat that covers and protects the voice box and trachea during swallowing). Both meningitis and epiglottitis can be caused by other bacteria, however. In rare cases, children may still develop H. influenzae type b infections. This can occur in a child who has not completed his or her series of immunizations or in older children who did not get  the vaccine as an infant.

How is H. influenzae transmitted?

The H. influenzae bacteria live in the upper respiratory tract and are usually transmitted by close contact with an infected person. Droplets in the air from a sneeze or cough can be inhaled and may also cause infection.

What are the symptoms of H. influenzae?

The following are the most common symptoms:

  • Otitis media (middle ear infection). May develop after a child has a common cold caused by a virus. Symptoms may include:

    • Unusual irritability

    • Trouble sleeping or staying asleep

    • Tugging or pulling at one or both ears

    • Fever

    • Fluid draining from ear(s)

    • Loss of balance

    • Hearing difficulties

    • Ear pain

    • Decreased appetite

  • Conjunctivitis. An inflammation of the conjunctiva of the eye. The conjunctiva is the membrane that lines the inside of the eyelid and also a thin membrane that covers the actual eye. Symptoms may include:

    • Redness

    • Swelling

    • Drainage from one eye or both eyes

    • Burning of the eyes

    • Photophobia (eyes sensitive to light)

  • Sinusitis. Infection in the sinuses. Symptoms may include:

    • Younger children:

      • Runny nose or congestion that lasts longer than 10 to 14 days. The discharge may become thick green, yellow, or blood-tinged.

      • Nighttime cough

      • Occasional daytime cough

      • Swelling around the eyes

      • Usually do not complain of headaches if less than 5 years of age

    • Older children:

      • Runny nose or cold symptoms that last longer than 10 to 14 days

      • Post nasal drip (nasal drainage that travels down the back of the throat)

      • Headaches

      • Facial discomfort (usually over the cheek bones or over the eyes which worsens when bending over)

      • Bad breath

      • Cough

      • Fever

      • Sore throat

      • Swelling around the eye (tends to be worse in the morning)

  • Epiglottitis. Due to the H. influenzae type b vaccine, epiglottitis is very rare in children and infants. Epiglottitis is an infection of the area of the throat that covers and protects the voice box and trachea (or windpipe) during swallowing. It can be fatal if not treated rapidly.

    • Some children start with an upper respiratory infection, such as a cold. Symptoms may include:

      • Quick onset of a very sore throat

      • Fever

      • Muffled voice

      • No cough

      • Shortness of breath

    • As the infection worsens, these symptoms may appear:

      • Drooling

      • Child is unable to talk

      • Child sits leaning forward

      • Child keeps his or her mouth open

      • Shortness of breath

  • Meningitis. Due to the H. influenzae type b vaccine, meningitis (due to this bacterium) is very rare in children and infants. Meningitis is an infection of the membranes that surround the brain and spinal cord. Symptoms may include:

    • In children older than 1 year:

      • Neck or back pain, especially when moving the chin toward the chest

      • Headache

      • Nausea and vomiting

      • Neck stiffness

    • In infants, symptoms are hard to pinpoint and may include:

      • Irritability

      • Sleeping all the time

      • Refusing a bottle

      • Crying when picked up or being held

      • Inconsolable crying

      • Bulging fontanelle (or soft spot)

      • Behavior changes

      • Fever

      • Often resists bending his or her neck when trying to play with or pick up a toy

The symptoms of H. influenzae infection may look like other medical conditions. Always see your child's healthcare provider for a diagnosis. Epiglottitis is life threatening and requires immediate medical attention.

How is H. influenzae diagnosed?

Your child's healthcare provider may diagnose the illness based on a physical exam and a medical history. Specific tests will depend on the location of the infection. In some cases, your child's provider may take a culture of fluid from the eye, ear, blood, or spinal fluid. In other situations, this may be not be possible and a diagnosis will be made based on your child's specific symptoms. Other tests may include:

  • Chest or neck X-ray. A test that produces images of internal tissues, bones, and organs.

  • Blood tests

What is the treatment for H. influenzae infections?

Regardless of the location, antibiotics are used to treat infections caused by H. influenzae. The length of treatment varies depending on the location and severity of the infection. Other therapy will be aimed at treating the symptoms present.

How can H. influenzae be prevented?

Immunization against type b, which is the most invasive strain of H. influenzae, is routinely given in a 3 to 4-part series. The vaccine is often referred to as "Hib" vaccine. Primary doses are given at 2 and 4 months of age or at 2, 4, and 6 months of age, based on the brand used by the doctor's office. A booster is then given between 12 and 15 months of age. If a child did not get the vaccine and is older than 5 years, he or she may not be immunized. Other populations that should be encouraged to receive the vaccine include the following:

  • Adults and children with sickle cell disease

  • People  without a spleen

  • Adults and children with weak immune systems

  • People who are HIV positive