Nobody knows exactly why kids get asthma but approximately 6.8 million kids in the United States suffer from it. As the search for a cause and cure continues, new clues are uncovered. A recently conducted study finds a link between antibiotic use in infancy and development of asthma by age 6. There’s also evidence of a gene variant but the research is still unclear as to which came first, the gene variant or the antibiotics.

Kids in the United Kingdom get asthma, too. That’s where this latest study took place. Professor Adnan Custovic, of the University of Manchester in England, enlisted the families of 916 children for the study. Antibiotic use and asthmatic symptoms of each child were documented from birth until age 11.

The research team noted every occurrence of prescribed antibiotics, wheezing, and asthma attacks throughout the study period. At intervals, when each child was 3, 5, 8, and 11 years old, a skin reaction test was administered to determine what, if anything, the child was allergic to. At age 11, blood samples taken from each child were assessed for immune system response to:

  • Rhinovirus (common cold)
  • Respiratory syncytial virus (RSV), a respiratory tract infection
  • Haemophilus influenzae (bacterium once mistakenly thought to cause the flu but causes other infections throughout the body, including sinusitis, conjunctivitis, pneumonia, and meningitis)
  • Streptococcus pneumoniae (causes bacterial pneumonia and other infections throughout the body)

The research team “noted a significantly higher risk of physician-confirmed” wheezing, severe wheeze, or asthma exacerbation (attack) after antibiotic prescriptions. In the first two years after a course of prescribed antibiotics, the child faced “significantly increased” bouts of asthma and wheezing severe enough to require hospitalization.

The skin reaction tests for allergies indicated the children who got antibiotics during the first year of life “had significantly lower induction of cytokines,” substances secreted by the immune system to fend off infection. These children showed reduced cytokine counts for defense against viral attack (rhinovirus and RSV) compared to children who did not get antibiotics during their first year. The cytokine response to bacteria was about the same regardless of early antibiotic use.

Children who got antibiotics early in life were more likely to have a specific gene variation in chromosome 17. It is unknown at this time if the variant — 17q21 — was there before the antibiotic use, perhaps making the child more susceptible to infection that required antibiotic treatment, or if antibiotics caused the gene to mutate.

Source: Custovic, Adnan, et al. “Assessing the association of early life antibiotic prescription with asthma exacerbations, impaired antiviral immunity, and genetic variants in 17q21; a population-based birth cohort study.” THE LANCET Respiratory Medicine. Elsevier Limited. May 15, 2014. Web. Jun 9, 2014.

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