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Tuesday, April 5, 2011

Severity of human rhinovirus infection in infants linked to maternal atopy

Human rhinoviruses (HRV) are known to be associated with asthma exacerbations in both children and adults. Additionally, bronchiolitis, which is usually associated with respiratory syncytial virus (RSV), is being associated with HRV as well. Typically, HRV is a viral infection associated with older children and has not been closely examined in infants with low risk for atopy.

Miller and colleagues in this month’s issue (J Allergy Clin Immunol 2011;127:883-891) examine the HRV burden in upper respiratory infections (URI) and bronchiolitis among children that had participated in the Tennessee Children’s Respiratory Initiative. They collected atopy risk information, clinical severity from hospital admission records, and performed type testing on the three HRV strains, A, B, and C.

Miller et al find that both URI and bronchiolitis in healthy infants are commonly caused by HRV. Maternal atopy and asthma were associated significantly with risk of more severe bronchiolitis, with maternal atopy conferring more than double the severity risk. Of the three strains of HRV, the newly described group, HRVC was very common and occurred more often in black infants thnt HRVA and HRVB. Infants infected with HRVB had higher severity scores and were more likely to require oxygen supplementation and have longer hospital stays.

The authors conclude that an infant’s susceptibility to severe HRV illness is significantly correlated to asthma and atopy susceptibility in the mother.

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Developing countries feeling the effects of increased traffic-related pollution

Studies of proximity to major roadways and asthma symptoms in urban environments are demonstrating that there is a significant relationship between the two. There are some reports that traffic pollution also affects FEV1. For the most part, these studies have measured pollution effects from multiple traffic networks, such as mass transit, in developed countries. Few studies in developing countries, with a focus on the impact of individual roadways, have been attempted.

Peru has the highest reported prevalence of childhood asthma symptoms in Latin America, and its capital, Lima, is representative of rapid urban development and expansion. In this month’s issue, Baumann et al. (J Allergy Clin Immunol 2011; 127:875-882) examine the effect of a single, high traffic road in a shanty town outside of Lima, Peru. They evaluate current asthma symptoms, pollution inside and outside the home, and allergen sensitivity as a marker of atopy.

The authors find asthma symptoms and atopy are inversely correlated to proximity to the high traffic road that runs through the shanty town. Airflow limitation was also negatively correlated to roadway proximity, but only in girls. The authors report no increase in airway inflammation or indoor pollution in homes closer to the road. Interestingly, they did find that greater than half the children that participated were atopic, with 23% testing positive to 3 or more allergens. The authors note that theirs is the first epidemiologic report correlating proximity to a roadway and atopy risk.

Tell us what you think. Please feel free to post your own comments below.