Invasive infections caused by haemophilus influenzae serotypes in twelve Canadian IMPACT centers, 1996-2001.
BACKGROUND
Haemophilus influenzae type b (Hib) immunization has changed the epidemiology of pediatric bacterial invasive disease. We describe the epidemiology of H. influenzae invasive infections in 12 Canadian pediatric tertiary care [Immunization Monitoring Program, ACTive (IMPACT)] centers during the era of universal immunization against this pathogen.


METHODS
Children with positive cultures for H. influenzae serotypes a to f (Hia to Hif) and nontypable H. influenzae from sterile sites were identified from the laboratory records at 12 IMPACT centers from January 1, 1996 to December 31, 2001. Hospital records were retrospectively reviewed for demographic and clinical information.


RESULTS
Of 166 H. influenzae cases, 58 (35%) were caused by Hib, 89 (54%) by non-b serotypes, and 19 (11%) were not serotyped. The non-b serotypes included: 25 Hia (28%), 4 Hid (4%), 2 Hie (2%), 11 Hif (12%), and 47 were nontypable isolates (53%). For patients with Hib and Hia infection, meningitis was the most common presentation, accounting for 40% and 52% respectively, whereas the most common presentation for nontypable serotypes was pneumonia, seen in 43% of cases. Epiglottitis was associated mainly with Hib. Aboriginal ethnicity was an important risk factor for Hia cases, accounting for 76% of patients with infections caused by this serotype. Mean duration of hospitalization, need for admission to a pediatric intensive care unit, and case fatality rates were similar for the cases because of Hib, Hia, Hif, and nontypable serotypes.


CONCLUSIONS
In 1996-2001, two-thirds of H. influenzae invasive disease in the 12 IMPACT centers was caused by non-b serotypes, which were associated with significant morbidity and mortality.
McConnell
Athena
A
Division of Pediatric Infectious Diseases, University of Saskatchewan, Saskatoon, SK, Canada. athena.mcconnell@usask.ca
Tan
Ben
B
Scheifele
David
D
Halperin
Scott
S
Vaudry
Wendy
W
Law
Barbara
B
Embree
Joanne
J
D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D018073:Haemophilus Vaccines / Q000008:administration & dosage* / Q000276:immunology; D006193:Haemophilus influenzae / Q000145:classification* / Q000276:immunology / Q000302:isolation & purification; D019741:Haemophilus influenzae type b / Q000276:immunology; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D009313:National Health Programs; D011159:Population Surveillance; D012703:Serotyping
D018073:Haemophilus Vaccines