Invasive disease may be manifest as pneumonia, bacteremia, meningitis, epiglottitis, septic arthritis, cellulitis, or purulent pericarditis; less common infections include endocarditis and osteomyelitis.
Meningitis with detection of Haemophilus influenzae type b antigen in cerebrospinal fluid (CSF)
Isolation of Haemophilus influenzae from a normally sterile body site (e.g., blood or CSF, or, less commonly, joint, pleural, or pericardial fluid)
Positive antigen test results from urine or serum samples are unreliable for diagnosis of H. influenzae disease. The 1997 case definition appearing on this page was originally published in the 1990 MMWR and re-published in the 2009 CSTE position statement 09-ID-33. Thus, the 1990, 1997, and 2010 versions of the case definition are identical.