As many as 450 million people are at risk from meningococcal A disease, the primary cause of epidemic meningitis across Africa. The disease kills thousands every year. Major group A epidemics occur every 7-14 years and are particularly devastating to children and young adults. The sickest patients typically die within 24 to 48 hours of the onset of symptoms. Of those who survive, 10 to 20 percent suffer brain damage, hearing loss or a learning disability.