My grandfather said to me when I was a boy, “if a child hasn’t eaten a bucket of dirt by age 5, it is not healthy”. My grandfather had absolutely no medical or scientific background but it appears his comments may have been physiologically sound.

Researchers in the past have suggested there is a bacteria in dirt that blocks an abnormal immune response leading to higher rate of allergies such as asthma, hayfever, urticaria and possibly even the most serious form of type 1 allergy, anaphylaxis.

The “hygiene hypothesis” has been around for a number of years and this latest study from the UK Institute of Cancer Research is yet another piece of evidence to support this way of thinking. Prof Mel Greaves, who headed the study, is suggesting that with the much cleaner environment of smaller families and better hygiene, young children are being exposed to less infections and thus their immune system is not being challenged properly. This is potentially predisposing them to more serious issues such as leukaemia. He is suggesting that the rising rates of acute lymphoblastic leukaemia may parallel the increasing “sterility of the modern world”.

We see everywhere now hand wipes and antiseptic lotions to ensure our hands and environments are germ free. When I was a child, we had sandpits and playgrounds created in a natural environment but these days everything is synthetic.

Acute lymphoblastic leukaemia is the commonest form of childhood leukaemia. It is estimated that 5% of children have the mutation which predisposes them to leukaemia and of these 5%, 1% will go on to develop leukaemia. Around 180 children per year are diagnosed with this condition in Australia alone. The highest incidence is in children between the ages of 2 to 4, with no obvious cause known to date.

It appears that acute lymphoblastic leukaemia is triggered by certain types of viruses, especially in children who have not suffered the common colds and flu typically seen in preschool age children.

I see the analogy here with exercise. If you do not have a regular exercise habit, when your body is called upon to perform some form of acute exercise it is much more difficult and causes significant fatigue in the attempt. In the same vein, if you have been exposed to a number of minor viruses throughout your life, it keeps your immune system active and more able to respond to more serious challenges.

The research was also supplemented by examining mice genetically engineered to develop acute lymphoblastic leukaemia. When they moved these mice from a germfree environment to a normal situation, the mice developed acute lymphoblastic leukaemia.

There have been a number of studies over the past decade suggesting the same is true for allergies and autoimmune disease. Again, when I was a child, we never heard of peanut allergies and now it appears that around 10% of children have some type of food allergy, the most common being allergy to peanuts.

Regardless, the next time your young child becomes ill with a virus, see it as a benefit to their immune system. If your child falls over and scratches their knee in the dirt by all means wash the knee but don’t be too concerned, it means their immune system is being activated.

I find it interesting that my wise grandfather who had a number of these quirky aphorisms is now being proven correct by modern science.