What Role Does Bacteria Play in Preventing Childhood Asthma?

Children exposed to bacteria, dirt and animal hair early in life are less likely to develop asthma. German research found that children raised on farms where the environment was likely to contain more microbes and fungi have lower asthma rates than children who grow up in cities.

Medical science has been looking for an explanation as to why asthma rates in the world’s most developed nations have more than doubled in three decades. A polluted environment such as a smoky or dusty one is generally thought to be the cause of asthma, a chronic inflammation of the airways.

Another theory that has attracted a lot of attention centres on the role of better hygiene – the environment in which children in the developed world are being raised is increasingly cleaner than for previous generations with less pollution, more sanitised surroundings and better general cleanliness.

The hygiene hypothesis put forward by researchers proposes that early childhood exposure to bacteria and fungi in the environment from the likes of animal hair and dirt helps a child’s immune system develop fully and so protects against chronic conditions such as asthma or allergies developing.

The German study, published in the New England Journal of Medicine, tested the hygiene hypothesis by looking at the difference in asthma rates among children in Bavaria who lived on farms and those in more urban environments, analysing dust samples from the bedroom of each child.

Their findings showed that the youngsters growing up in what were muckier, dirty and dustier environments, exposed to more bacteria than their counterparts, were 30-50% less likely to develop asthma, with evidence also suggesting that some types of bacteria actually increased the child’s protection against the condition.

The study offers hope of possible breakthroughs in creating a vaccine or other types of protective treatment that will stop children developing asthma. Further research is now needed to isolate exactly which microbial exposures have the key role in protecting the immune system.