This article offers two explanations for the correlation of asthma with early infancy antibiotics: a need for the immune system to be trained by early exposure to microbial toxins and a need for normal intestinal microflora in the development of normal immune response. Another possibility is that the rashes and infections that prompted the use of antibiotics share a common cause with the subsequent asthma.

Matthew H. Fields
Ann Arbor, Mich.

The article reported a correlation but no confident explanation for the relationship between receiving antibiotics and later developing asthma. “Ulcer bug may prevent asthma” ( SN: 10/27/07, p. 270 ), which reports that children with Helicobacter pylori in their stomachs are less likely to get asthma, seems to offer a convincing answer.

Virginia Brock
Rock Island, Ill.