Influence of maternal asthma on the cause and severity of infant acute respiratory tract infections

BACKGROUND: Respiratory syncytial virus (RSV) and rhinovirus infections are the most common significant infant respiratory tract illnesses and are associated with increased but differential risks of childhood asthma. OBJECTIVE: We sought to determine whether maternal asthma is associated with higher odds of infant respiratory tract infection with rhinovirus versus RSV and increased infection severity. METHODS: Mother-infant dyads were enrolled from 2004-2008 during an infant respiratory tract infection (104 with rhinovirus and 279 with RSV). Mothers were classified into mutually exclusive groups (atopic asthma, nonatopic asthma, and no asthma). We determined viral cause using PCR and the severity of the infant’s respiratory tract infection using the bronchiolitis severity score. Adjusted relative odds of maternal asthma with viral cause were calculated by using logistic regression. Proportional odds models assessed the association of maternal asthma and infant infection severity. RESULTS: Infants with a mother with atopic asthma compared with infants whose mothers did not have asthma were more likely to have rhinovirus versus RSV infection (adjusted odds ratio, 2.42; 95% CI, 1.19-4.90). Similarly, among infants with rhinovirus, having a mother with atopic asthma was associated with increased infection severity (adjusted odds ratio, 3.10; 95% CI, 1.21-7.98). This relationship was not seen among infants with RSV. CONCLUSIONS: Clinically significant rhinovirus infection during infancy was more strongly associated with having a mother with atopic asthma than clinically significant RSV infection. Having a mother with atopic asthma was associated with increased severity of infant rhinovirus but not RSV infections. Infants with rhinovirus were more likely to have a familial atopic predisposition, which might partly explain the subsequent increased asthma risk.