Haemophilus influenzae (Invasive Disease) (H. influenzae)

2015 Case Definition

CSTE Position Statement Number: 14-ID-05

Clinical Description

Invasive disease may manifest as pneumonia, bacteremia, meningitis, epiglottitis, septic arthritis, cellulitis, or purulent pericarditis; less common infections include endocarditis and osteomyelitis.

Laboratory Criteria

Confirmatory Lab Evidence:

Isolation of Haemophilus influenzae from a normally sterile body site*; or
Detection of Haemophilus influenzae-specific nucleic acid in a specimen obtained from any normally sterile body site*, using a polymerase chain reaction (PCR) assay

Supportive Lab Evidence:

Detection of Haemophilus influenzae type b antigen in cerebrospinal fluid (CSF)

Case Classification

Confirmed:

Isolation of Haemophilus influenzae from a normally sterile body site* OR
Detection of Haemophilus influenzae-specific nucleic acid in a specimen obtained from a normally sterile body site* by PCR assay

Probable:

Clinical symptom of meningitis with laboratory detection of Haemophilus influenzae type b antigen in CSF

For this disease/condition, Confirmed, Probable, and Unknown case statuses are included in the released case count.

Comment

Positive antigen test results from urine or serum samples are unreliable for diagnosis of Haemophilus influenzae disease and should not be used as a basis for case classification.

Case Classification Table

Criterion for Haemophilus influenzae, Invasive	Probable	Confirmed
Clinical Evidence:
Meningitis	N
Laboratory Evidence:
Isolation of Haemophilus influenzae (any type) from a normally sterile site*		S
Detection of Haemophilus influenzae-specific nucleic acid in a normally sterile body site using a validated polymerase chain reaction (PCR) assay*		S
Detection of Haemophilus influenzae type b (Hib) antigen in CSF	N

Notes:

S = This criterion alone is sufficient to classify a case

N = All "N" criteria in the same column are necessary to classify a case

* Normally sterile body sites include blood, bone, CSF, internal body site�, pericardial fluid, peritoneal fluid, pleural fluid, synovial/joint fluid. An abscess specimen obtained from a normally sterile body sites is also counted as a surveillance case.

� Internal body sites include specimen obtained from surgery or aspirate from one of the following: lymph node, brain, heart, liver, spleen, vitreous fluid, kidney, pancreas, ovary, or vascular tissue.