Exposing children to pets and germs reduces asthma risk

Exposing your child early on to pets and germs reduces their risk of developing asthma, according to a study.

Previous studies have shown that reducing allergen exposure in the home helps control the chronic disease when it is already established. 

Now the new findings suggest that exposure to allergens early in life, before asthma develops, has a preventive effect.

Contact with cats, dogs, mice and cockroaches by age three months was linked to a lower chance of having asthma by age seven, found researchers funded by the National Institutes of Health (NIH), an agency of the US Department of Health.

Exposure to certain bacteria in house dust during infancy was also associated with a reduce risk.

‘We are learning more and more about how the early-life environment can influence the development of certain health conditions,’ said NIAID director Anthony Fauci.

‘If we can develop strategies to prevent asthma before it develops, we will help alleviate the burden this disease places on millions of people, as well as on their families and communities.’

Asthma is a chronic disease that intermittently inflames and narrows the airways, causing wheezing, coughing, breathlessness and a tight chest.

In children, it sometimes disappears or improves during the teenage years, although it can return later in life. 

More than 8 percent of children in the US currently have asthma according to the Centers for Disease Control and Prevention. More than one million children in the UK (that’s one in 11) suffer with it, according to Asthma UK.

Key findings 

The ongoing Urban Environment and Childhood Asthma (URECA) study, which is funded by NIH, enrolled 560 newborns at high risk for developing asthma because at least one parent has asthma or allergies who have been followed since birth.

Researchers found higher concentrations of cockroach, mouse and cat allergens present in dust samples collected from the children’s homes during the first three years of life – at age three months, two years and three years – were linked to a lower risk of asthma by age seven.

A similar association was found for dog allergen, although it was not ‘statistically significant’, meaning it could be due to chance.

However, additional analysis showed that exposure to higher levels of all of these four allergens at age three months was associated with a lower risk of developing asthma. 

The team also found evidence that certain bacteria in house dust, which was collected in the first year of life, may protect three-year-olds from recurrent wheezing, a risk factor for developing asthma. 

‘Our observations imply that exposure to a broad variety of indoor allergens, bacteria and bacterial products early in life may reduce the risk of developing asthma,’ said James Gern, the principal investigator of URECA and a professor at the University of Wisconsin-Madison.

‘Additional research may help us identify specific targets for asthma prevention strategies.’

In addition, the results confirm previous research linking development of childhood asthma to prenatal exposure to tobacco smoke, maternal stress and depression. 

The findings were published in the Journal of Allergy and Clinical Immunology.