The ethnic origin, age, and sex of the 41 patients are shown in Table 1. Thirty-two patients (78.0 percent) were native Canadian Indians. The sex ratio was equal in the native group, although males preponderated among the nonnatives. Seventy-five percent of the native children were between four and 12 months of age, while more than 50 percent of the nonnatives were older than one year of age. All native children in the series lived on federal reserve land in the province of Manitoba, while residences of nonnatives were divided evenly between the city of Winnipeg and rural areas. Nearly one half (46.4 percent) of the infection occurred between November and March, with the remainder distributed throughout the year.
An adenovirus was grown from the tracheal secretions of 26 of the 29 patients in whom isolation was attempted (Table 2). Type 3 was the preponderant ADV, and was grown in 14 cases; types 1 and 2 accounted for three cases each, and types 5 and 6 for one case each. In four instances the virus was not typed. Only 12 of the 26 patients with positive isolates had sera tested for antibody titers, and all of these showed serologic response to ADV infection. Twelve of the 41 patients only had serologic evidence of the infection.
Bronchiolitis in the young pediatric patient is usually self-limited and most frequently due to respiratory syncytial virus (RSV). Although adenovirus (ADV) accounts for less than 5 percent of the admitted patients, it can cause severe disease that ends fatally or leads to serious residual lung damage. These earlier reports have usually been of single cases, nosocomial outbreaks, and isolated epidemics. The present retrospective study was undertaken to further delineate the epidemiologic, clinical, and radiologic features of ADV bronchiolitis seen recently in Manitoba over a 43-year period.