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 United States 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 receive 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 individual. 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 of H. influenzae infections. However, each child may experience symptoms differently. Symptoms may include:

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

    • Unusual irritability

    • Difficulty 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

    • Nausea and vomiting

    • Decreased appetite

    • Nasal congestion

  • 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 that lasts longer than 10 days. The discharge is usually thick green or yellow, but it can be clear.

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

      • Quick onset of a very sore throat

      • Fever

      • Muffled voice

      • No cough

    • As the infection worsens, the following symptoms may appear:

      • Drooling

      • Child is unable to talk

      • Child sits leaning forward

      • Child keeps his or her mouth open

  • Meningitis. Due to the H. influenzae type b vaccine, meningitis (due to this bacteria) 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 and/or back pain, especially when moving the chin toward the chest

      • Headache

      • Nausea and vomiting

      • Neck stiffness

    • In infants, symptoms are difficult 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

      • Is often resistant to bend their neck when trying to play with or pick up a toy

The symptoms of H. influenzae infection may resemble other medical conditions. Always consult your child's doctor for a diagnosis.

How is H. influenzae diagnosed?

Your child's doctor may diagnose the illness based on clinical examination and a medical history. Specific tests will depend on the location of the infection. In some cases, your doctor 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 diagnostic tests may include:

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

  • Blood tests

What is the treatment for H. influenzae infections?

Treatment for H. influenzae greatly depends on which area of the body is infected. Specific treatment for H. influenzae will be determined by your child's doctor based on:

  • Your child's age, overall health, and medical history

  • Extent of the disease

  • Your child's tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the disease

  • Your opinion or preference

Regardless of the location, antibiotics may be 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 supportive (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 administered in a three- or four-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 receive the vaccine and is older than 5 years, it may not be necessary for him/her to be immunized. Other populations that should be encouraged to receive the vaccine include the following:

  • Adults and children with sickle cell disease

  • Individuals without a spleen

  • Adults and children with weakened immune systems

  • Individuals who are HIV positive


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