Percentage of Meningitis Cases Caused by Haemophilus influenzae. Eight different studies were conducted on patients diagnosed with meningitis caused by H. influenzae from 1965-2004. ES1966-1989 reported H. influenzae to be the cause of meningitis in 4.1% of 7,809 patients . In ES1966-1968 H. influenzae was responsible for 12% of 123 culture-positive cases . ES1971-1975 study of 1,333 patients with ABM reported only 2.6% of meningitis cases were due to infection with H. influenzae . ES1977-1978 H. influenzae was reported to be responsible for 2.6% of the total 1627 CSF specimens and 12% of the 350 culture-positive isolates . ES1998-2000 on children less than 6 years, 39% of the 228 patients' cultured- confirmed disease 39% showed H. influenzae . ES2000 revealed that H. influenzae was responsible for 14.3% of 223 positive bacterial culture meningitis cases . ES2002-2003 on 310 children clinically diagnosed with meningitis identified 202 cases as ABM where 21% of the ABM cases were caused by H. influenzae . ES1998-2004 H. influenzae was responsible for 20% of the 843 cases of culture-positive patients . The asterisks represent epidemiological studies reporting an average during the entire period of the study.