The epidemiology of invasive disease due toHaemophilus influenzaeserotype a in the Canadian North from 2000 to 2010

Abstract

IntroductionThe International Circumpolar Surveillance (ICS) project is a population-based surveillance network. Since 2000, Canada has participated in the ICS Invasive Bacterial Disease Working Group's surveillance of invasive disease due to Haemophilus influenzae (Hi).MethodsA standardized case report form containing demographic and clinical information was completed for all reported Hi cases in the study regions. Isolates were sent to a reference laboratory for confirmation and serotyping. Analysis was conducted on all Hi serotype a (Hia) cases reported from 2000 to 2010. The northern Canadian population was estimated using Statistics Canada information.ResultsOf the 130 Hi cases reported from 2000 to 2010, 72 (56% of cases with serotype information) were due to Hia. The number of Hia cases reported each year ranged from 2 in 2008 to 13 in 2010. The average Hia incidence over the 11 years was 4.6 cases per 100,000 population per year. The majority of Hia occurred in infants less than 2 years of age (73% of cases). This age group had an average annual incidence of 87.5 cases per 100,000 population. Among cases for which ethnicity was indicated, 91% of Hia cases reported Aboriginal status with the average incidence being 6.9 cases per 100,000 population per year. The most common clinical presentation was meningitis (reported in 37% of cases), followed by bacteraemia (34%) and pneumonia (27%). More than 90% of cases were hospitalized, and there were 4 deaths, resulting in a case fatality ratio of 5.6%.ConclusionIn the last decade, Hia has become an important cause of morbidity and mortality in the Canadian North. More detailed surveillance information from a national perspective is needed. Further work on vaccine development should be encouraged.

Invasive bacterial diseases in Northern Canada, 2006–2013

“…These findings are consistent with previous Canadian and international circumpolar studies (3)(4)(5)(6)(21)(22)(23).…”

“…Some studies suggested that poor health, environmental and housing conditions of Indigenous children may be potential risk factors (28)(29)(30)(31). Hia has been a predominant serotype in Northern Canada since the beginning of ICS (5,22,32), whereas non-typaeble Hi and type f are more common in other circumpolar regions (32). This report also demonstrates the significant increasing trend of Hia.…”

Collaboration on a public health-driven vaccine initiative

“…Similar to Hib, Hia causes severe illness such as meningitis, sepsis and bacteremic pneumonia in young children under the age of five. Since northern Canada has a relatively high indigenous population and Hia, being similar to Hib including its epidemiology, has replaced Hib as a cause of significant burden of invasive diseases in the post-Hib vaccine era (17). This trend has also been observed in Alaska, U.S.A. (18).…”

Maladies bactériennes invasives dans le Nord du Canada de 2006 à 2013

“…Ces résultats sont cohérents avec les résultats des études circumpolaires canadiennes et internationales précédentes (3)(4)(5)(6)(21)(22)(23) …”