Infectious Diseases

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 US due to effective vaccine development, which has been available since 1988. The more serious strain was responsible for causing 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). In rare cases, children may still develop H. influenzae type b infections. This can occur if the child has not completed their 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 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
  • diarrhea
  • decreased appetite
  • congestion
    
    
• conjunctivitis - an inflammation of the conjunctiva of the eye. The conjunctiva is the membrane that lines the inside of the eye 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 greater 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 greater than 10 days
    • complaints of drip in his/her throat from his/her nose
    • headaches
    • facial discomfort
    • bad breath
    • cough
    • fever
    • sore throat
    • swelling around the eye (tends to be worse in the morning)
      
      
• epiglottitis - most cases of epiglottitis are caused by H. influenzae type b. Children who have received the H. influenzae type b vaccine (HIB vaccine) are unlikely to get epiglottitis. Epiglottitis is an infection of the area of the throat that covers and protects the voice box and trachea (or windpipe) during swallowing.
  
  
  • 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
    • unable to talk
    • child sits leaning forward
    • child keeps his or her mouth open
      
      
• meningitis - Haemophilus influenzae type b used to be a common bacterial cause of childhood meningitis. Meningitis caused by this particular bacteria is now rare in children who have received the HIB vaccine. Meningitis is an infection of the membranes that surround the brain and spinal cord. Symptoms include the following:
  
  
  • in children older than 1 year:
    
    
    • neck and/or back pain
    • headache
    • nausea and vomiting
    • neck stiffness
      
      
  • in infants, symptoms are difficult to pinpoint and may include:
    
    
    • irritability
    • sleeping all the time
    • refusing a bottle
    • cries when picked up or being held
    • inconsolable crying
    • bulging fontanelle (or soft spot)
    • behavior changes

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

How is H. influenzae diagnosed?

Your child's physician 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 physician 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 uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
  
  
• CT scan of head- a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the head.
  
  
• blood tests

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 physician 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

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).

Prevention of H. influenzae:

Immunization against type b, which is the most invasive strain of H. influenzae, is routinely administered in a three- or four-part series. The first vaccine is received at 2 months of age and the two subsequent doses are given at about 4 months and 6 months. 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 them 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