Meningococcal DiseaseMeningococcal disease can be caused by various types of the meningococcal bacterium. These can cause meningitis and blood poisoning; these are serious illnesses that kill 1 in 10 of children who get them, with a further 1 or 2 out of 10 children suffering some form of permanent disability such as brain damage, scarring, hearing loss or even amputation of part of a limb. Over three quarters of cases occur in children under five years of age. Thankfully the disease is relatively uncommon in most parts of the world. Though there are at least 13 types (serogroups) of meningococcus, nearly all disease is caused by one of the 6 groups: A, B, C, W-135, X and Y.
Men A (Serogroup A meningococcus)Men A is the most common cause of meningococcal disease worldwide and is especially common in the 'meningitis belt' of sub-Saharan Africa where it causes large epidemics, sometimes affecting up to 1 in 10 of the affected population. It is advisable to be protected against Men A before travelling to affected areas.
Men B (Serogroup B meningococcus)Before the introduction of the vaccine, Men B caused the majority of meningococcal disease in then UK and also much of the developed world including Western Europe, North America and Australasia. 87% of all meningococcal disease in the UK was caused by the B serogroup.
Men C (Serogroup C meningococcus)Men C is also more common in the developed world where it causes occasional local outbreaks. Men C is seen less in areas where the Men C vaccine has been introduced.
Men W-135 (serogroup W-135 meningococcus)Cases of Men W have been steadily increasing in England and Wales over recent years.Under five-year-olds are most likely to be infected and one in eight who contract the illness will die.
Men X (serogroup X meningococcus)Men X is becoming increasingly common in parts of Africa
Men Y (serogroup Y meningococcus)Men Y is the only group that has been increasing in prevalence over recent years in the UK where there are now around 80 cases a year. It is also on the rise in the USA.
Before immunisation against meningococcus type C started in 1999, about 1300 children under 5 years of age contracted Meningococcal disease every year in the UK. Of these,about half had Meningitis B and a little over a third had Meningitis C, against which a vaccine was introduced in the UK in 1999. The remaining cases were caused by other strains including W135 and Y. Groups C and W135 are particularly dangerous, killing 1 in 7 children who catch these strains.
Meningococcal disease occurs mainly in the first few years of life, though teenagers are also susceptible.
Picture courtesy CDC