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Every parent's guide to good and bad germs

Children need to play in the dirt to develop healthy immune systems. You just need to time it right. 

3 May 2018
5 minute read

mother washing daughters hands in sink

We’re frequently told that the best way to stay healthy is to wash our hands, to prevent the spread of germs. At the same time, we hear about “good dirt” and how early exposure to common microorganisms reduces allergies and other illnesses later in life. Since these two types of information seem to conflict with each other, we tried to get to the bottom of the matter. We spoke to Dr Deon Smith, a Cape Town paediatrician, about when children should be exposed to dirt and germs and when they should be protected from them – and when adults should wash their own hands.

A baby’s developing immune system Deon explains that from a practical point of view, it all depends on the age of the child. “Babies under six months of age have immature immune systems, and parents must be vigilant. If the baby is preterm, then they should be even more vigilant as the baby didn’t have the opportunity to acquire its mom’s antibodies in the last month of pregnancy.


“Vigilance” he says, involves careful handwashing, controlling visits from sick people, and sterilising any bottles or dummies that the baby might use. 

After six months, he says, “it’s fine to give a bottle a good clean, but not worry too much about steam sterilisation or disinfectant. “By then, babies are starting to sit or crawl on the floor and put all sorts of things in their mouths. You don’t have to pull those things out of their hands and disinfect everything. If you’re worried about an item, just run it under cold water. It doesn’t need to spend hours in Milton.”

He says that by this age, children end up putting their parents’ shoes in their mouths or getting licked by the dog, and this kind of exposure is good for developing immunity. “Children this age also sometimes end up touching dog poo in the garden or eating cat food from the bowl. While I wouldn’t actively recommend doing this, there’s certainly no need to panic if it happens.”

He does recommend deworming all household pets and doing the same for your children when they are older. And if other children come to visit who are visibly ill, then it’s worth disinfecting the toys that they played with.

The hygiene hypothesis Doctors and scientists believe that this kind of exposure to dirt is actually very healthy for your child. Research has shown that children who live in environments that are too clean end up with higher rates of asthma, hay fever, autoimmune diseases and other illnesses later in life. Other studies show that kids who grow up on farms have fewer allergies. The idea is that exposure to contaminants found in their natural surroundings gives children’s immune systems a workout, and in the absence of this workout, the immune system turns on non-pathogenic matter (matter that doesn’t cause disease), like pollen or the body’s own tissue, resulting in allergies and autoimmune diseases.

Simply put, for a healthy immune system, and for better overall health, children need to play in the dirt, without worrying too much about what kind of dirt it is.

But what about washing your hands? Hand-washing has been described as the single most important step you can take to prevent disease. This is because bodily fluids and germs are commonly passed from person to person via the hands. You touch a sick person’s hand, or a doorknob, or a shopping trolley where germs have been distributed from a sick person’s hand. Then you touch your own mouth, eyes and nose, and are infected by the fluid found there.

It is the potential for contact with other sick human beings, rather than the dirt found in your home or garden, that you should be worrying about.
Deon says that if someone is known to be ill in a house, particularly a house with a small baby, then of course their hands should be washed thoroughly and exposure to the baby should be limited.

Under normal circumstances, just do the appropriate hygienic washing of hands.

“If you have a pathogenic viral or bacterial infection, then of course you must be strict with handwashing and so on,” he says. “But under normal circumstances, just do the appropriate hygienic washing of hands after visiting the bathroom, before meals and when you return home.”

If your child is in a creche or preschool, try to instil good handwashing practices with the support of their teachers, as they are likely to be exposed to numerous infections in this environment. And of course, adults should also avoid coming into direct contact with sick people so that they don’t contract viral infections themselves.

When to worry As Deon explained, babies have immature immune systems, so we need to be careful about exposure to germs. Children are most at risk of contracting illness between the ages of six months and two years old. After that, the immune system steadily develops until reaching full maturity between ten and twenty years of age. During adult life, it dips during pregnancy or other immune-related disorder like HIV, or cancer treatment like chemotherapy, and then begins to taper off again at around 60. If you are taking care of a baby or an immunocompromised patient, you should be more vigilant about hand washing and exposure to sick people.

The best way to wash your hands In a normal household, a wash with soap and water for 20 seconds is fine to deal with most of the pathogens that may lurk there. If you need to use a hand rub rather than running water or are looking after a person whose immunity is compromised, Deon recommends an alcohol rub over an antibacterial hand wash, as it has been found to be the most effective method of removing the greatest number of germs from your hands.

Avoid using antibacterial hand sanitisers because it is contributing to the growing problem of antibiotic resistant bacteria.

A healthy compromise It’s good to know that you don’t have to worry too much about your baby’s exposure to the outside world. Be sensible about hand washing, but don’t sterilise everything your baby may come into contact with. As your baby grows up and for your own health, hand washing remains your best weapon against viral infection, so make regular washes a part of your family’s daily routine.

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