Haemophilus influenzae (Invasive Disease) (H. influenzae)
The 1997 case definition appearing on this page was previously published in the 1990 MMWR Recommendations and Reports titled Case Definitions for Public Health Surveillance [MMWR 1990;39(RR13)] (available at http://www.cdc.gov/mmwr/preview/mmwrhtml/00025629.htm). Thus, the 1990 and 1997 versions of the case definition are identical.
Invasive disease caused by Haemophilus influenzae may produce any of several clinical syndromes, including meningitis, bacteremia, epiglottitis, or pneumonia.
Isolation of H. influenzae from a normally sterile site (e.g., blood or cerebrospinal fluid [CSF] or, less commonly, joint, pleural, or pericardial fluid)
Probable: a clinically compatible case with detection of H. influenzae type b antigen in CSF
Confirmed: a clinically compatible case that is laboratory confirmed
Positive antigen test results from urine or serum samples are unreliable for diagnosis of H. influenzae disease.