Disease caused by Neisseria meningitidis is a worldwide problem (1 ). Epi- demics of meningococcal disease regularly occur in the “meningitis belt” of sub-Saharan Africa and in Asia (2 –5 ) and high or increasing levels of endemic meningococcal disease have been reported recently in the UK (6 ), New Zealand (7 ), Cuba (8 ), Brazil (9 ), Norway (10 ), and the Pacific Northwest of the United States (11 ). Meningococcal disease predominantly affects children and has a high mortality, which has remained unchanged for 30 years, despite advances in antibiotics and intensive care (12 ). Efforts have therefore been made to understand the pathophysiology of the disease and use this knowledge to improve treatment and develop novel therapies.