Fever, headache, confusion, seizures, amputations or death. Meningitis is a very serious brain infection that can affect the body in many ways and needs to be treated within 24 hours of contracting the disease. The World Health Organization estimates that there are close to three million cases per year. Between the four main causes of meningitis, the WHO is particularly concerned about bacterial meningitis, which is caused by the infectious bacteria Streptococcus pneumoniae.