Which age groups have the highest prevalence of Haemophilus influenzae infections?

Updated: Jun 11, 2021
  • Author: Joseph Adrian L Buensalido, MD; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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In general, Hib infections are rare in patients older than 6 years because of the acquisition of secondary immunity; however, immunocompromised individuals remain susceptible.

Hib meningitis primarily affects children younger than 2 years, with a peak frequency in infants aged 6-9 months. Epiglottitis is most common in children aged 2-7 years but can also occur in adults. Hib pneumonia typically occurs in children aged 4 months to 4 years. Hib causes septic arthritis and cellulitis in children younger than 2 years; before the conjugate vaccine became available, Hib was the leading cause of arthritis in this age group. Hib septic arthritis also occurs in adults. Prior to introduction of the Hib vaccine, Hib was the leading cause of occult bacteremia after Streptococcus pneumoniae in children aged 6-36 months. In the vaccine era, Hib occult bacteremia is rare. H influenzae otitis media can occur at any age but is most common in children aged 6 months to 6 years.

NTHi causes neonatal sepsis through vertical transmission via the female genital tract, maternal sepsis, and, infrequently, other invasive diseases. It also causes otitis media, sinusitis, bronchitis, and pneumonia in all age groups.

In 2006, the Active Bacterial Core Surveillance Report found that NTHi infection was most common among persons younger than one year and those aged 65 years or older, accounting for 6.5 and 4.3 cases per 100,000 general population, respectively. [11] By 2015, NTHi rates were 4.88 and 2.72 per 100,000 in the same age groups, respectively, although rates were highest in individuals aged 85 years and older, at 11.37 per 100,000. [12]

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