Lower respiratory tract infections in Inuit infants on Baffin Island

Background: It: has long been suspected that Canadian Inuit children suffer from frequent severe lower respiratory tract infections (LRTIs), but the c auses and risk factors have not been documented. This study assessed the in fectious causes and other epidemiologic factors that may contribute to the severity of LRTI in young Inuit children on Baffin Island. Methods: A prospective case study was carried out at the Baffin Regional Ho spital in Iqaluit, Nunavut, of infants less than 6 months of age, who were admitted to hospital between October 1997 and lune 1998 with a diagnosis of LRTI. Immunofluorescent antibody testing was used to identify respiratory viruses, and enzyme immunoassay (EIA) and polymerase chain reaction (PCR) w ere used to test for Chlamydia trachomatis. Demographic and risk factor dat a were obtained through a questionnaire. Results: The annualized incidence rate of admission to hospital for bronchi olitis at Baffin Regional Hospital was 484 per 1000 infants who were less t han 6 months of age; 12% of the infants were intubated. Probable pathogens were identified for 18 of the 27 cases considered in our study. A single ag ent was identified for 14 infants: 8 had respiratory syncytial virus, 2 ade novirus, 1 rhinovirus, 1 influenza A, 1 parainfluenza 3 and 1 had cytomegal ovirus. For 4 infants, 2 infectious agents were identified: these were ente rovirus and Bordetella pertussis, adenovirus and enterovirus, cytomegalovir us and respiratory syncytial virus, and respiratory syncytial virus and ade novirus. C. trachomatis was not identified by either EIA or PCR. All infant s were exposed to maternal smoking in utero, second-hand smoke at home and generally lived in crowded conditions. Interpretation: Inuit infants in the Baffin Region suffer from an extremely high rate of hospital admissions for LRTI. The high frequency and severity of these infections calls for serious public health attention.