Meningococcal infection is a serious illness caused by a bacterium known as meningococcus.
Many adults and children carry these germs without ill effects. Many of the meningococci seem to be harmless and may prevent more dangerous meningococci getting into the body. Only rarely do meningococci overcome the body's defences and cause illness. There are a number of different groups of meningococci. There were over 2000 cases reported in the UK in 1998 and numbers have risen in the first few weeks of 1999.