Recently, H. influenzae serotype A (Hia) infections have been reported more frequently globally and in indigenous populations. We reviewed case characteristics and sequelae of invasive Hia cases to describe these infections in Alaska where rates of Hia infection are elevated.
A case was defined as first isolation of Hia from an otherwise sterile site, between January 2002 and July 2014, in a child aged less than 10 years who was a resident of Alaska. Cases were identified from statewide bacterial disease surveillance. Information was abstracted from medical records to determine clinical characteristics at presentation and outcomes within 1 year.
Cases occurred in 36 children of median age 7 months (interquartile range, 5–11 months); 24 (67%) were male, 34 (94%) resided in a remote village, and 34 (94%) were of Alaska Native race. Developmental, metabolic or chronic cardiopulmonary conditions were reported in 13 (36%) children; of whom 1 had known immune deficiency. Clinical presentations included 15 (42%) with meningitis; 9 (25%) with only bone, joint, or soft tissue infection; 7 (19%) with bacteremic pneumonia; and 5 (14%) with bacteremia of unknown focus. Overall, 7 children (19%) required ventilation, 7 (19%) required surgical debridement and 3 (8%) required neurosurgery; 32 (90%) required transfer by air travel and 10 (28%) were admitted to a pediatric intensive care unit. Four children (11%) died. At 1 year, 4 more children (11%) had ongoing neurologic sequelae.
Hia caused meningitis, bone and joint infection, sepsis, and pneumonia, similar to H. influenzae serotype B. Invasive Hia infections in Alaska have occurred predominantly in Alaska Native infants in rural communities. Although one-third of cases had pre-existing conditions, most occurred without known comorbidity. Clinical syndromes were frequently severe, requiring surgical debridement, mechanical ventilation, or neurosurgery. One in five children either died or had chronic sequelae after 1 year. An effective vaccine would prevent significant morbidity and mortality in affected populations.
R. Singleton, None
M. C. Engel, None
M. Hirschfeld, None
J. Klejka, None
K. Rudolph, None
T. Hennessy, None
M. Bruce, None