Haemophilus influenza type a (Hia)

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Background:

  • Gram-negative bacteria that most commonly causes meningitis, pneumonia with bacteremia, septic arthritis, and cellulitis (often rapidly progressing) with bacteremia.
  • First case of invasive Hia identified in Alaska in 2003

Epidemiology:

  • from 2014-2018, 107 cases were reported with 91% of the reported cases in the state of Alaska in Alaska Natives and 69% from the YK Delta region
  • median age: 1.1 yrs
  • incidence for Alaska Native children <2y/o living in the YK Delta region: 781/100,000 (similar to Hib prior to introduction of the vaccine in 1991)

Individual Risk Factors for Hia Carriage:

  • Crowded house (>1.5 people per room)
  • age of individual (<10 y/o higher risk)
  • 3 or more smokers in house
  • Contacts

Diagnosis:

  • must have high clinical suspicion
    • with high fevers (>104) without a source
    • rapidly progressing cellulitis and/or ill appearing (give Ceftriaxone empirically in addition to staph coverage with Vancomycin)
  • obtain blood, wound, and/or CSF cultures
    • YKHC lab can culture H. flu, but does not report serotype (A through F)
    • (all invasive H. flu isolates are sent to AIP (Alaska Investigations Program, a branch of the CDC, (907 729-3400) for serotyping)
  • Can send culture fluids to the state for PCR testing (this is usually done if the culture is positive for H. flu OR negative due to pretreatment OR negative and highly suspicious for Hia)

Management:

  • all cases from 2014-2018 were susceptible to Amoxicillin
  • Patients are often given Ceftriaxone empirically until cultures return, then narrow as appropriate.
  • If susceptible to Amoxicillin and not meningitis, one dose of Ceftriaxone is sufficient to clear the infection (no need for chemoprophylaxis at end of therapy) followed by Amoxicillin oral therapy
  • consider Dexamethasone in the setting of clinical meningitis
  • All children with meningitis should be referred to audiology and have an hearing evaluation one month after hospital discharge.

Critical Times for Affected Patients:

  • from 2014-2018, 25% of children <10y/o died or had severe neurologic outcomes
  • if high suspicion for meningitis, do not delay antibiotics for lumbar puncture
  • if high suspicion for Hia with cellulitis, add Ceftriaxone

Chemoprophylaxis Recommended:

  • Public Health nurses will perform contact investigation and dispense medication
  • similar to recommendations for Hib cases
    • household contacts of a person with invasive Hia when at least one household member is <4y/o or an immuno-compromised child
    • preschool and child care center contacts when 2 or more cases of Hia have occurred within 60 days
    • index pt is <2y/o or has susceptible household member and not treated with cefotaxime or ceftriaxone
  • NOT recommended for pregnant women
  • rifampin 20mg/kg (max dose 600mg) po daily x4 days
    • for infants <1 month old, some recommend lowering to 10 mg/kg
    • start as soon as possible, but benefit shown if started 7 or more days after index patient hospitalization
  • NOTE to Pediatricians: see the HIA folder in the Peds folder for a sample Hia prophylaxis letter to families (HiA PPX letter)

Resources/References


Common/Unique Medical Diagnoses