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Haemophilus influenzae type b

Hib disease is caused by the bacterium Haemophilus influenzae type b. Humans are the only host of these bacteria. Infants and children less than five years of age are most vulnerable to Hib infections.

Despite the similar name, H. influenzae type b is not the same as influenza and it is not a virus.

Introduction

Hib disease was the most common cause of life-threatening bacterial infection in children under five years of age prior to introduction of the Hib vaccine in 1994. Since then, the number of children hospitalised for Hib meningitis or epiglottitis has decreased by around 90%.

How you get it

Hib bacteria are commonly carried in the nose and throat and do not usually cause illness.

The bacteria can be transferred from person to person through contact with respiratory droplets in the air and on surfaces by coughing or sneezing, or through direct contact with respiratory secretions.

Living with pre-school and school-aged siblings, living in a crowded household or having another respiratory infection, such as seasonal influenza, can increase the chance of carrying the bacteria.

Household and other close contacts of someone with the disease, such as through intimacy, sharing food and beverages, and infants and children attending day care or an early childhood education centre, are at increased risk of disease.

Symptoms

Like several other diseases (e.g. pneumococcal and meningococcal disease), the symptoms and presentation of Hib will depend on where the bacteria is in the body. All three of these diseases can present as meningitis (inflammation of the membranes around the brain) or bacteraemia (infection in the bloodstream, sometimes called septicaemia or blood poisoning). However, they can present in other ways. Hib, for example may present as epiglottitis (severe swelling in the throat) or pneumonia.

Symptoms of meningitis

  • Fever, loss of appetite, vomiting
  • Drowsiness, headache, sensitivity to bright light, neck stiffness
  • Signs may be vague and non-specific in young infants; they may have a bulging fontanelle

Symptoms of epiglottitis

  • Fever
  • Breathing difficulty
  • Noisy breathing
  • Difficulty swallowing
  • Drooling

A child with epiglottitis may sit with an extended neck and their tongue sticking out to help them breathe.

Treatment

Children with signs of meningitis or epiglottitis should see a doctor very urgently.

Hib infection is treated with antibiotics. Supportive therapy may be required which could involve hospitalisation and intensive care.

Risks

After Hib bacteria passes into the blood and the person develops invasive Hib disease the risks are, for:

  • Meningitis
    • Of those who develop meningitis and survive, 20-40% will have long term neurological damage
    • One person out of every 20 infected with Hib meningitis will die despite early identification and treatment
  • Septicaemia (blood infection)
  • Epiglottitis (severe swelling in the throat) that can affect breathing
  • Pneumonia and inflammation in other organs, such as heart, joints, bones and skin

Infants and children younger than five years of age have an increased risk of Hib disease. Those aged 4 to 18 months and Māori or Pacific children aged under two years are have the greatest risk of Hib meningitis. Children aged two to four years have an increased risk of Hib epiglottitis.

Some people with certain medical conditions have an increased risk of infection, for example, those without a functioning spleen, and those who are immune compromised from a disease or treatment of a disease.

Prevention

An effective vaccine is available and used for all infants and young children, and for older children and adults with impaired immune systems. In addition:

  • Avoid overcrowded living conditions, if possible
  • Avoid sharing food, drinks and eating utensils
  • Limit close physical contact when coughing and sneezing
  • Remember to cover your mouth and wash hands thoroughly after coughing or sneezing

Haemophilus influenzae type b (Hib)

Complications of disease

  • Blood infection (septicaemia)
  • Meningitis, especially in children less than two years of age, 20-40% of survivors have long term nerve damage, death in 5% despite treatment
  • Severe swelling in the throat (epiglottis)
  • Pneumonia
  • Joint, heart, bone, skin inflammation
  • Long term nerve damage
  • Death in around 1 case out of 20 despite treatment

Responses to vaccine

Common responses

  • Irritability
  • Sleepiness
  • Unusual crying

Rare responses

  • Hives
  • Itching
  • Convulsion

As with any medicine, very rarely, severe allergic reactions occur following immunisation

Last updated: Apr 2017