Bacterial meningitis in children aged two months to 12 years is usually caused by three different microbes: streptococcus pneumonia, neisseria meningitidis or haemophilus influenzae type B (Hib).
Neisseria meningitidis causes the classical case of meningococcal meningitis in which the child develops a rapidly spreading red rash on its body.
This rash is recognisable by the fact that when it is pressed on with a clear glass, the rash does not disappear.
Meningitis caused by Hib usually presents in a more subtle way. In a child aged two to four years, parents need to watch for listlessness, unusual irritability and a high temperature that does not come down in response to paracetemol. The child may not want to be touched or moved. He may resist efforts to bend forward at the head.
In an infant with the infection, the soft spot on top of the child's skull (the fontanelle) may bulge outwards. Unlike meningococcal meningitis, Hib does not cause the classic skin rash.
The current concern about Hib meningitis does not represent a spreading epidemic of infection. Rather, the concern is that a small number of children aged from one to four years who have been vaccinated against Hib have outgrown their immunity to the bacterium.
Most of these will simply become Hib carriers and will not develop any disease. It is estimated that no more than 12 children will develop invasive Hib infection during the coming winter. And not all of these cases will result in meningitis; some will develop septic arthritis (an infection of the joints) or epiglottitis (an infection of part of the voicebox).
The success of the Hib vaccine is shown in the complete absence of invasive Hib infection in children less than 12 months in the last year in the Republic. Some 95 per cent of all Hib disease occurs before the age of five. Up to 75 per cent of children with haemophilus meningitis die, while others may be left with neurological complications.
A total of 200,000 children require booster Hib vaccinations in the catch-up programme which is now expected to commence in October. The Health Service Executive has decided that when it receives the first batch of booster Hib vaccinations, those children aged 13 to 14 months will be immunised first by family doctors.
When this cohort of children is completed, children aged two to three will be vaccinated.
The final part of the "catch-up" vaccination programme will be aimed at children aged three to four years.