This is a serious illness caused by septicaemia due to Meningococcus (i.e. Neisseria meningitidis). Meningococcus is transmitted from person to person by droplet spread (coughing and sneezing). It often causes asymptomatic colonisation of the upper respiratory tract only. However, some people get a septicaemia, meningitis or both. Meningococcal infection is more common in overcrowded conditions where epidemics may occur.