Risk factors for severe bronchiolitis caused by respiratory virus infections among Mexican children in an emergency department

Robledo-Aceves, Mireya; Moreno-Peregrina, María de Jesús; Velarde-Rivera, Fernando; Ascencio-Esparza, Elba; Preciado-Figueroa, Francisco M.; Caniza, Miguela A.; Escobedo-Melendez, Griselda

Other environmental factors that we found to be associated with severe viral bronchiolitis in our bivariate analysis were living in overcrowded conditions, having a pest (e.g., termite, flea, tick, or rodent) or cockroach infestation in the house, and coexisting with pets. Although previous reports have not shown that overcrowded living conditions is associated with severe viral bronchiolitis in infants, [17, 35] overcrowding is a well-known risk factor for severe bronchiolitis. [1, 8, 25] In addition, these associated environmental factors, that were found in our study, may reflect that our hospital primarily serves a low-income population that lacks health insurance. One earlier study reported that living in low-income conditions influences the severity of viral bronchiolitis, [30] but the presence of pets, pest infestation in the house, or farm animals did not. [17, 35] However, the contribution of these environmental factors to worse outcome of viral bronchiolitis in infants and young children is well studied; thus, studies in similar populations are required to analyze these associations. Family factors that were associated with severe viral bronchiolitis in this study were maternal history of asthma and allergies, as have been previously reported in Mexico. [17] However, risk factors such as exposure to cigarette smoking during pregnancy were not associated with severe bronchiolitis in the children studied, contrasting with findings reported previously in Spain and North American. [2, 26] This could be a secondary effect of campaigns against smoking during pregnancy that have been undertaken in Mexico, but are not related with the lack of association between severity of bronchiolitis and pregnancy smoking in this study. Comparable results have been published in Italy. [14] However, activities that prevent smoking Table 4 Multivariate analysis of risk factors associated with severe viral bronchiolitis.