Haemophilus influenzae Disease

Confirmed Case
Clinical evidence of disease with laboratory confirmation of infection:

• Isolation of H. influenzae (serotypes a, b, c, d, e, f and non-typeable isolates) from a normally sterile site  OR
• Isolation of H. influenzae (serotypes a, b, c, d, e, f and non-typeable isolates) from the epiglottis in a person with epiglottitis  

Clinical / Probable Case
Clinical evidence of invasive disease¹ with laboratory evidence of infection:

• Demonstration of H. influenzae type b antigen in cerebrospinal fluid OR
• Demonstration of H. influenzae DNA in a normally sterile site OR
• Buccal cellulitis or epiglottitis in a child < 5 years of age with no other causative organisms isolated  

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¹ Clinical evidence of invasive disease due to H. influenzae includes meningitis, bacteremia, epiglottitis, pneumonia, pericarditis, septic arthritis, or empyema.

Notes: Current vaccination programs only provide coverage for H. influenzae serotype B.  However, all H. influenzae isolates that cause invasive disease are considered to meet the case definition for the following three reasons:

1) Most invasive H. influenzae disease is now caused by non-serotype B isolates.

2) Inclusion of all isolates will not change the laboratory diagnosis in any way, as all isolates already require rigorous biochemical tests and serotyping.

3) Data captured on incidence of diseases due to non-type b isolates may have an impact on public health policy and vaccine development in the future.