What is Hib meningitis?
Hib meningitis is caused by bacteria called Haemophilus influenzae type b.
Until the introduction of the Hib conjugate vaccine, this was the main form of meningitis in young children in the UK and Ireland. It affects mainly children under 4 years of age1 . Nowadays, Hib is rare in all age groups. In the UK, cases in adults tend to occur in people at the ages most likely to mix with children, both as parents and grandparents2.
Hib can cause a range of serious illness, most frequently meningitis. Hib meningitis is an inflammation of the lining of the brain and spinal cord. It has the same symptoms as other kinds of bacterial meningitis.
- In the early stages, a person usually feels unwell, with fever, headache and vomiting, just like many mild illnesses.
- Typical meningitis symptoms - stiff neck and dislike of bright light normally happen later.
- As the disease gets worse the person affected may become very sleepy and difficult to wake, confused or delirious, and may have seizures (fits).
Babies and young children do not often get a stiff neck or dislike of bright lights, but
- They may refuse to feed and be irritable with a high-pitched or moaning cry, especially when you pick them up.
- They may have blotchy, pale or bluish skin.
- Their body may be stiff, with jerky movements or go floppy and lifeless.
- The soft spot on a baby's head may be tense or bulging.
People with Hib meningitis do not normally get a rash. A rash is typical of meningococcal infection, which is the most frequent cause of meningitis, and usually occurs together with septicaemia (blood-poisoning).
Nowadays in the industrialised world, at least 95% of people with Hib meningitis recover, but it can be fatal, and as many as one survivor in eight may be left with long-term neurological problems such as deafness, brain damage, problems with co-ordination and epilepsy. Studies from the US have found neurological problems in as many as 45%of survivors.
Other severe Hib diseases include pneumonia, epiglottitis (inflammation of the back of the throat), septicaemia (not usually with meningitis), cellulitis (inflammation of tissue), arthritis, and pericarditis (inflammation of the heart lining)3.
Hib can also cause milder ailments like ear infections and minor respiratory illness.
How do you get Hib meningitis?
Hib bacteria are found only in humans, and live temporarily in the back of the nose and throat.
Hib infection is spread through close contact with mucus or droplets from the throat of someone who carries the bacteria. Hib bacteria are too fragile to live outside the human body. Although we don't know exactly how long they can survive outside, we do know that, in general, prolonged close contact is necessary to pick up Hib bacteria. The majority of people who carry Hib do not become ill, which means that we are most likely to meet the bacteria through contact with perfectly healthy carriers. Before Hib vaccine was introduced, young children quite commonly carried Hib bacteria.
The incubation period for Hib is uncertain, however it is generally agreed that when Hib disease occurs, it develops within days of exposure to the bacteria1 .
Who is at risk?
Only a small fraction of the people who acquire Hib bacteria fall ill with the disease and the reasons for this are not entirely understood. People with a deficient immune system, such as those without a spleen, are at higher risk. Although the disease is now rare, doctors report all cases to the Public Health doctor. Depending on their age and whether they have been vaccinated, some household contacts of a case may be more at risk than the general public. The Public Health doctor decides what action to take in the cases when it is needed.
Is there a Hib vaccine?
A conjugate vaccine (made from a tiny fragment of the bacteria's sugar-coat attached to a protein) against Hib was introduced in the UK and Ireland in 1992, and provides long-lasting immunity. Since the introduction of the Hib vaccine, the incidence of meningitis cause by Haemophilus influenzae has been reduced by over 90%, across the UK and Ireland4,5 .
Find out more about the Hib vaccine.
1. Davies EG, Elliman DAC, Hart AC, Nicoll A, Rudd P for the RCPCH. Manual of Childhood Infections. 2nd Edition, 2001; WB Saunders, London.
2. McVernon J, Trotter CL, Slack MPE, Ramsay ME. Trends in Haemophilus influenzae type b infections in adults in England and Wales: surveillance study. 2004. BMJ 329: 655-658
3. Department of Health. Immunisation against infectious diseases. Chapter 16: Haemophilus influenzae type B (Hib) pages 127-135. Ed Salisbury D, Ramsay M and Noakes K. 2006. Third edition. TSO. http://www.dh.gov.uk/en/Policyandguidance/Healthandsocialcaretopics/Greenbook/DH_4097254 (accessed 17 May 2007).
4. JCVI Statement: Haemophilus influenzae type b (Hib) Disease and Hib Vaccine. Executive Summary. http://www.advisorybodies.doh.gov.uk/jcvi/hib.pdf (accessed 17 May 2007).
5. Health Protection Surveillance Centre. Hib FAQs, How safe and effective is the Hib vaccine? http://www.immunisation.ie/en/HealthcareProfessionals/Hib/#howsafe (accessed May 2007).