Haemophilus influenzae Invasive Disease

Reportable by Laboratories and Providers

About this Reportable Disease

Infectious agent:  Haemphilus influenzae

Description of illness:Haemphilus influenzae is a pleomorphic gram-negative coccobacillus and is isolated in 2 major forms: unencapsulated and encapsulated.  Unencapsulated strains are termed nontypable and are rare causes of serious infection but are a common cause of ear infections in children and bronchitis in adults; they are a rare cause of chorioamnionitis and neonatal sepsis.  Encapsulated form has six generally recognized types: a, b, c, d, e, and f. Only type B (“Hib”) is vaccine-preventable; all invasive disease isolates are serotyped at the state public health laboratory.H. influenzae type b (Hib) colonizes nasopharynx, in some persons the organism enters the bloodstream and causes invasive disease.  Before the introduction of vaccines, Hib was the leading cause of bacterial meningitis and other invasive disease among children <5 years of age; it is now rare due to effective routine immunization. The most common types of invasive disease are meningitis, epiglottitis, pneumonia, arthritis, and cellulitis.. Hearing impairment or other neurologic sequelae occur in 15%–30% of survivors. The case-fatality rate is 2%–5%, despite appropriate antimicrobial therapy.   

Interactive Disease Data


Laboratory Reporting for this Disease

Haemophilus influenzae

TEST NAME Haemophilus influenzae
DISEASE/DISORDER Influenza, bacteremia
ALTERNATE NAME(S) None
METHODOLOGY Culture
SPECIAL INSTRUCTIONS

Isolate submission is REQUIRED for laboratories.
ORDERING INFORMATION Lab Web Portal

Specimen Requirements

Patient Preparation
  • None
Specimen Collection
  • Pure culture from normally sterile sites and/or clinical specimens such as CSF, whole blood, and serum

Isolates: Chocolate agar plate/slant

Clinical specimen: Sterile screw-cap container
Specimen Labeling
  • Specimen should be labeled with at least two unique patient identifiers along with specimen source and match accompanying test order.
Specimen Processing
  • None
Specimen Storage and Preservation
  • Isolates should be stored at ambient temperature.
  • Clinical specimens (CSF, whole blood and serum) should be refrigerated (2-8°C) after collection. If transport/testing cannot be perfomed within 96 hours of collection specimens should be frozen  at (-15°)C or lower.
Specimen Transport
  • Ship clinical specimens (CSF, whole blood and serum) refrigerated (2-8°C). If specimen cannot be transported/tested within 96 hours of collection, ship frozen (-15°C or lower) on Dry Ice.
  • Ship isolates at ambient temperature. Do not send isolates refrigerated or frozen.
  • All infectious substance shipments must conform to U.S. Department of Transportation (DOT) Hazardous Materials Regulations (HMR 49 C.F.R. Parts 171-180). 
Specimen Acceptability and Rejection
  • Specimens that do not meet all specimen requirements will be rejected.
Testing Location
  • Nashville

Laboratory Reporting

Reporting requirements apply to all laboratories located within Tennessee, as well as laboratories outside of Tennessee that test residents of Tennessee, including laboratories located within healthcare facilities. Healthcare providers and laboratories in the same healthcare facility both have a duty to report. The type of organisms and analytes laboratories must report to TDH for 2026 are indicated, and there are several ways laboratories can report results to TDH.

 

Information about this Reportable Disease for Healthcare Providers

Clinical Summary

  • Invasive Haemophilus influenzae (Hi) disease occurs when Hi is isolated/detected from a normally sterile site (e.g., blood, CSF, pleural fluid, joint fluid) and can present as meningitis, bacteremia/sepsis, epiglottitis, pneumonia, septic arthritis, or cellulitis; Hib is vaccine-preventable, and other Hi types (including nontypeable) have been increasing in recent years.
  • Diagnosis relies on clinical suspicion plus laboratory confirmation, with culture and/or nucleic acid amplification testing (PCR/NAAT) supporting diagnosis and public health response; coordination with public health laboratories may be needed for species confirmation and serotyping (e.g., Hib).
  • Management is time-sensitive for suspected invasive disease: initiate appropriate empiric therapy per syndrome (e.g., meningitis/sepsis pathways) and tailor to susceptibilities/serotype as results return; ensure appropriate supportive care and source control when indicated.
  • Public health actions may include case reporting, serotyping, and (for Hib) consideration of chemoprophylaxis and vaccination recommendations for close contacts based on CDC guidance; in Tennessee, invasive H. influenzae is a reportable condition.

Healthcare Provider Reporting

Healthcare reporting requirements apply to all providers located within Tennessee, as well as providers whose patients reside in Tennessee.

Providers must report cases of all diseases and conditions listed through one of these methods:

• Mail or fax a completed PH-1600 form to your local health department or fax to the state health office at (615) 741-3857

• Send automatically via electronic case reporting (eCR). See this TDH webpage for more information on eCR, register at the Trader Partner Registration website, or contact MU.Health@tn.gov for assistance.

• Submit online via NBS. NBS is TDH's reportable disease system. To request an NBS account for reporting Complete this user survey to request an NBS account for reporting. 

• Blood lead levels can be sent via fax ( (615) 741-3857), entered online, or reported using the instructions at this link. 

Information about this Reportable Disease for the Public

What It Is

Invasive Haemophilus influenzae disease is a serious infection caused by the bacterium Haemophilus influenzae when it spreads into normally sterile parts of the body (such as blood, cerebrospinal fluid, or joints). Despite the name, H. influenzae does not cause influenza (the flu).

Who Is At Higher Risk

Severe disease can occur at any age, but the risk is higher for certain groups. One preventable form—Haemophilus influenzae type b (Hib)—is best prevented by routine childhood vaccination, and invasive disease can also be caused by other H. influenzae types, including nontypeable strains.

Signs and Symptoms

Invasive H. influenzae can cause different serious illnesses depending on where the infection occurs, including meningitis, bloodstream infection (sepsis), pneumonia, epiglottitis (a throat infection that can block the airway), skin/soft tissue infection, and joint infection. Because these conditions can worsen quickly, prompt medical evaluation is important

How It Spreads

H. influenzae can live in the nose and throat and spread between people through respiratory droplets/secretions during close contact. In some people, the bacteria invade into the bloodstream or other normally sterile sites, causing invasive disease.

Prevention

Routine childhood vaccination helps prevent Hib, one important cause of invasive disease in children. Keeping recommended vaccines up to date reduces risk and helps protect infants and others at higher risk for severe outcomes.

This Page Last Updated: March 25, 2026 at 8:53 PM