Haemophilius influenzae type b

Hib

  • Overview
  • In Depth
  • Vaccines
  • Video

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 especially vulnerable to Hib infections.

Despite the similar name, Haemophilus influenzae type b is not the same as influenza/seasonal flu which is caused by viruses.

A brief history

Worldwide, Haemophilius influenzae type b (Hib) was the leading cause of bacterial meningitis for children less than five years of age before a vaccine was introduced in the US in 1987.

NZ Situation

Before the Haemophilus influenzae type b (Hib) vaccine was introduced to the New Zealand childhood immunisation schedule  in 1994, Hib disease was the most common cause of life-threatening bacterial infection in children less than five years of age. Since 1994 the number of New Zealand children less than five years of age being hospitalised for Hib meningitis or epiglottitis (severe swelling in the throat) has decreased by around 90%.

Compared with 1992 when there were 140 cases of Haemophilus influenzae type b disease in children less than five years of age, between 2001-2011 less than 10 cases of disease have occurred each year in this age group.

In 2014, two cases of Hib disease were confirmed. One of these was in a child aged less than five years, this compares with no cases in children under five years in 2013, one in 2012, three in 2011 and five in 2010.

Symptoms

Meningitis (inflammation of the membranes around the brain)

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

Epiglottitis (severe swelling in the throat)

  • Fever, difficulty breathing, noisy breathing, difficulty swallowing and drooling of saliva.
  • A child with epiglottitis may sit with an extended neck and their tongue sticking out to help them breathe.
How do 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 from a person coughing or sneezing, or through direct contact with respiratory secretions.

What are the risks?

If Haemophilus influenzae type b bacteria pass into the blood, it may take 2-10 days to cause disease.4 A person with invasive Hib disease may develop:

  • Meningitis (inflammation of the membranes around the brain).
  • 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.
  • Bacteraemia (blood infection).
  • Epiglottitis (severe swelling in the throat) that can affect breathing.
  • Pneumonia (lung inflammation), pericarditis (inflammation of the layer around the heart), septic arthritis (joint inflammation), osteomyelitis (bone inflammation), and cellulitis (inflammation of the tissues under the skin).
Who is the most at risk?

Infants and children less than five years of age have an increased risk of Hib disease. Those aged 4-18 months and children less than two years who are Māori or Pacific Peoples have the highest risk of Hib meningitis. Children aged 2-4 years have an increased risk of Hib epiglottitis.

Living with pre-school and school-aged siblings, living in a crowded household or having another respiratory infection, e.g. seasonal influenza, can  increase a person’s chances of carrying the bacteria.

Some groups are also at increased risk of infection: household and other close contacts of someone with the disease, e.g. those who have been intimate or shared food and beverages, and infants and children attending day care or an early childhood education centre with a person who has Hib disease.

Some people with medical conditions that affect their immune system have an increased risk of infection, e.g. their spleen has been removed or doesn’t work properly, or those who are immune compromised from a disease or treatment of a disease.

Treating the symptoms
  • Haemophilius influenzae type b (Hib) infection is treated with antibiotics.
  • Hib associated illnesses may require additonal treatment and hospitalisation.
  • Children with signs of meningitis or epiglottitis should seek medical care.
Preventing the disease from spreading
  • An effective vaccine is available and used for all infants and young children, and also for older children and adults  with impaired immune systems.
  • 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.
Risk of disease vs. vaccine side effects
Haemophilius influenzae type b Effects of disease Side effects of vaccine

Haemophilius influenzae type b (Hib) is a bacterial illness that can cause meningitis, epiglottitis and pneumonia. Despite its name Haemophilus influenzae type b is not related to influenza/seasonal flu caused by viruses.

  • Blood infection (septicaemia).
  • Inflammation of the membranes around the brain (meningitis), especially in young children.
  • Severe swelling in the throat (epiglottitis).
  • Pneumonia.
  • Joint, heart, bone, skin inflammation.
  • Long term nerve damage.
  • Death for around 1 person out of 20 cases despite treatment.
Common side effects
  • Mild pain, redness and swelling around injection site.
  • Decreased appetite.
  • Vomiting or diarrhoea.
  • Irritability, restlessness.
  • Sleepiness.
  • Unusual crying.
  • Limb swelling after the 4th or 5th vaccine dose.
Uncommon side effects
Rare/very rare side effects
  • Hives.
  • Itching.
  • Temporary low platelet count.
  • Persistent inconsolable screaming.
  • Hypotonic, hyporesponsive episode (HHE) in infants.
  • Convulsion.
  • Severe allergic reaction (anaphylaxis).

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 especially vulnerable to Hib infections.

Despite the similar name, Haemophilus influenzae type b is not the same as influenza/seasonal flu which is caused by viruses.

Causative organism

Haemophilius influenzae is a pleomorphic gram-negative coccobacillus. Of the encapsulated strains, there are six antigenically distinct polysaccharide types (a-f); type b is the most virulent. Non-encapsulated or non-typeable strains do not react with typing antisera.

Humans are the only natural host.

Clinical signs, symptoms and complications

Meningitis (inflammation of the membranes around the brain)

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

Epiglottitis (severe swelling in the throat)

  • Fever, difficulty breathing, noisy breathing, difficulty swallowing and drooling of saliva.
  • A child with epiglottitis may sit with an extended neck and their tongue sticking out to help them breathe.
  • Nontypable and non-type b capsular type strain infections can be asymptomatic.
Method of transmission

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 from a person coughing or sneezing, or through direct contact with respiratory secretions on fomites.

Neonates can acquire infection intrapartum by aspiration of amniotic fluid or contact with infected genital tract secretions.

Public health significance

Haemophilius influenzae type b (Hib) is a notifiable disease in New Zealand.

Hib disease is a major cause of morbidity and mortality in children less than five years of age worldwide.

  • Hib meningitis is more common in infants and children less than two years of age.
  • Survivors of Hib meningitis have a 20-40% risk of long-term neurodevelopmental impairment.
  • Hib epiglottitis is more common in children 2-4 years old.
  • The case fatality rate for invasive Hib disease is 5% in countries with developed economies.

In New Zealand, overcrowded housing is a significant risk factor.

New Zealand epidemiology

Before the Haemophilus influenzae type b (Hib) vaccine was introduced to the New Zealand childhood immunisation schedule  in 1994, Hib disease was the most common cause of life-threatening bacterial infection in children less than five years of age. Since 1994 the number of New Zealand children less than five years of age being hospitalised for Hib meningitis or epiglottitis (severe swelling in the throat) has decreased by around 90%.

Prevention
  • An effective vaccine is available and used for all infants and young children, and also for older children and adults  with impaired immune systems.
  • 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.

Hib vaccine is recommended and funded for:

  • Children under 5 years of age (in Infanrix®-hexa for infants and as Act-Hib™ from 15 months of age).
  • Children aged 5 years and older and adults who are post-haematopoietic stem cell transplantation; post-chemotherapy; pre- or post-splenectomy; pre- or post-solid organ transplantation; pre- or post-cochlear implant; on renal dialysis; a severely immunosuppressive regimen; or who have functional asplenia.

 

Treatment
  • Hib infection is treated with antibiotics.
  • The recommended antibotics are rifampicin, ceftriaxone and ciprofloxacin.
  • Invasive Hib disease usually requires hospitalisation and further treatment.

Infanrix®-hexa

DTaP-IPV-HepB/Hib

Infanrix®-hexa is used for primary and booster vaccination of infants and children to protect against diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis and disease caused by Haemophilus influenzae type b. Infanrix®-hexa can also be used for catch-up immunisation for children up to their 10th birthday.

Act-HIB®

Haemophillus influenzae type b (Hib)

Act-HIB® is used for a booster vaccination at 15 months of age to protect against disease caused by Haemophilus influenzae type b. The vaccine is also used for vaccination of children aged 5 years of age and over and adults with some chronic medical conditions.

Listed below are the available videos for this disease