Incidence of invasive Haemophilus influenzae infections in children with sickle cell disease

Background: Children with sickle cell disease (SCD) are at increased risk for invasive infection with encapsulated bacteria. Antibiotic prophylaxis and immunizations against Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) have decreased the overall incidence of invasive infections and have shifted distribution of serotypes causing disease toward those not covered by immunizations. We sought to determine the current incidence of invasive H. influenzae infections in children with SCD and to describe the clinical features and management of these infections.

Methods: Microbiology reports of a large pediatric tertiary care center were reviewed to identify all isolates of H. influenzae detected in sterile body fluid cultures from January 1, 2010 to December 31, 2017. Results were compared with the center's comprehensive clinical database of all children with SCD to identify all cases of children ages 0 to18 years with SCD with invasive H. influenzae disease for the same time period.

Results: We captured 2444 patients with SCD, with 14,336 person-years. There were eight episodes of H. influenzae bacteremia in seven children with SCD (five type f, two non-typable, one type a). Most episodes (7 of 8) were in children < 5 years. The incidence rate of invasive H. influenzae in SCD was 0.58/1000 person-years for ages 0 to 18 years and 1.60/1000 person-years for children age < 5 years. There were no deaths from H. influenzae infection.

Conclusions: In the era of universal antibiotic prophylaxis and immunization against Hib, invasive H. influenzae disease due to nonvaccine serotypes remains a risk for children with SCD, particularly those under five years of age.