Invasive disease caused by Haemophilus influenzae type a in Northern Ontario First Nations communities.

Seven epidemiologically unrelated cases of invasive Haemophilus influenzae type a (Hia) disease were identified in First Nations communities of Northwestern Ontario, Canada, in 2004-2008. In all cases, Hia was isolated from blood. The clinical presentation in most of the cases was moderately severe and all patients responded to antibiotic therapy. Laboratory analysis of Hia isolates from Northwestern Ontario indicated striking similarities in their phenotypic and genotypic characteristics. The findings are discussed in the context of current epidemiology of invasive Hia disease. Our data along with some published studies by others suggest an increased susceptibility to this infection among North American indigenous populations.