Percentage of pneumococcal meningitis cases based on studies conducted over 39 years. A representation of nine different studies conducted on patients diagnosed with meningitis due to different etiological agents from 1965-2004. In the study ES1965-1968 on 644 cases of ABM 3% (21 patients) of the cases reported were due to pneumococcal infection . ES1966-1968 conducted on 187 meningitis patients S. pneumoniae was responsible for 29% of 123 culture-positive cases . ES1966-1989 conducted on 7,809 meningitis or encephalitis patients, reported that 7.3% of total cases were due to pneumococcal infection . A retrospective review ES1971-1975 of 1,333 patients with ABM, reported 7.9% of meningitis cases diagnosed with pneumococcal meningitis . ES1977-1978 revealed pneumococci was the prevalent bacteria detected . Surveillance of 2047 patients with meningitis in ES1998-2000 was conducted to determine the etiology of the disease in children less than 6 years. 30% of 228 patients of the cases confirmed by culture were positive for S. pneumoniae. However, in children older than 12 months and less than 6 years, S. pneumoniae was the leading causative agent . ES2000revealed that S. pneumoniae compromised 32% of ABM . ES2002-2003 on 310 children clinically diagnosed with meningitis; 202 patients were diagnosed with ABM; 13.9% of total meningitis cases were infected with S. pneumoniae and 21.3% of ABM . ES1998-2004S. pneumoniae was responsible for 42% culture-positive bacterial meningitis cases . The asterisks represent epidemiological studies reporting an average during the entire period of the study.