How clean should we keep our kids?

Most of us have heard the saying, "cleanliness is next to godliness" — kill those germs and you'll have happy, healthy kids. Melbourne mum, Limor Kain, is a staunch supporter of this theory. She has the cleanest house in the suburb and she's constantly on germ patrol.

"I have a problem with cleaning and I admit it. I clean a lot, especially around the children," she says.

It's anti-bacterial all the way for her children Cory, Taylor and Dillon — they must be Australia's most spotless children!

"I do agree that kids do need to be exposed to some amount of germs to a degree. But I think a lot of the germs that are in the hands are quite dangerous," Limor says.

In comparison is the Retano kids where mum Sarah's philosophy is let them loose in the garden — the more dirt, the better.

"It's a bit like having a vaccination. You're going to put some of the illness or the disease into you in order for you to be able to produce the antibodies and everything else. It's the same with dirt. That's my excuse and I'm sticking to it," says Sarah.

So for dirty faces, it's spit and polish and, yes, it is okay to eat food once it's been on the floor.

"It's just that it's gone that step a little bit too far. That we worry too much," Sarah says.

So who is right? To find out, Brooke visits the Institute of Child Health Research in Perth to ask allergy expert, Professor Peter Sly.

Brooke: So should we let our kids get out there and eat dirt?
Professor Sly: I think having the kids outside playing in the dirt is very good for them. It certainly helps mature their immune systems, they are getting lots of maturational stimuli as opposed to people sitting inside playing on computer games.

Professor Sly bases his research on the "hygiene hypothesis" where the idea is that a baby is born germ-free, but in the first few weeks of life, bacteria colonise the skin and gut, helping the immune system mature. The theory goes that if little ones aren't exposed to enough bacteria and dirt, their immune systems fail to learn and mistakenly attack everyday items like pollen, causing an allergic reaction.

Allergies and asthma are on the rise — could that be because our kids' immune systems simply aren't mature enough?

Take the case of 10-year-old Sateki Avard: "I first noticed Sateki's allergies when he was two and I gave him two cashews and his face blew up," says Feona Weggelaar.

As he grows, Sateki's allergies are getting worse, so Feona has come to Professor Sly to find out what else he is allergic to and whether he's one of those kids with a weakened immune system.

The professor tests for allergens that are common in their environment — things like mould, grasses and dust mites are all put onto Sateki's skin.

The effect is immediate on his arm — poor Sateki is allergic to just about everything tested!

Brooke wonders if she'd be in the same boat: "I developed asthma and allergies when we shifted from NSW to Melbourne."

Two minutes into her allergy test and Brooke's ready to scratch her arm off.

"I'm really itchy, really itchy. I just want to scratch," she says.

But she'll have to endure a full 15 minutes to find out the real cause.

Brooke: So what does this mean for me?
Professor Sly: These reactions say you are very strongly allergic to grass. The other one that's quite strongly positive is the cat.

Brooke: That makes sense. Every time I go near a cat my eyes go crazy. Maybe that's because I didn't have pets when I was a kid, but I did play in dirt.

Sadly, it's not that straightforward, says Professor Sly: "It's not as simple to say that an individual person, if you do live in a clean house you will develop allergies, if you live in a dirty house you won't — it's not that simple on an individual basis. But it's on populations where these risk factors make sense."

Take kids who grow up on farms. Lots of studies show that, as a group, they're less likely to develop problems because of early exposure to dirt and allergens. But is it possible to do a similar thing artificially?

Professor Sly has developed a world first — an allergy vaccine that'll do just that.

"How it works is by stimulating the immune system to recognise these allergens as being harmless and developing what's called immunological tolerance against them," he says.

Two-year-old Ben Rosman is taking part in early clinical trials — he's allergic to milk protein, some vegetables and he has eczema. He's also living proof that there's not much that could have been done to prevent it.

"He was a breastfed baby, he had solids at six months, he lives in a house where I'm not paranoid about dirt, we have a hairy golden retriever that lives in the house and I wouldn't say I'm neurotic about keeping the house clean," says mum Lucy Rosman.

Lucy gives him a daily liquid vaccine containing massive doses of common allergens like grasses, cats and dust mites. His immune system has no choice but to deal with them.

"What we hope with this vaccine is we will be able to prove that this is a way to prevent allergies and asthma," says the professor.

So far Ben is responding well, but it's early days yet. If it works the vaccine won't be available for a few years. So what can you do to protect your kids in the meantime?

"Really the best advice is not to be too fanatical about trying to keep their environment clean," says Professor Sly.

Here are the professor's top tips for allergy-free living:

• Pets are good.
• Playing in the dirt is good too.
• Smoking is bad.
• Keeping a clean house is good, but don't be fanatical!

"Well from what I've seen, I reckon kids that grow up playing in dirt, have a better than even chance of developing a decent immune system. Allergies make our lives miserable, but for some they can be life-threatening, so if you have any concerns, always consult your GP," says Brooke.

Fast facts

• How safe are your kids when it comes to sharing backyards with animals? Can children catch worms from pet dog? Yes. Round worm eggs are passed out in dog poo and can survive in the soil for some time. If your child accidentally eats some, they can get worms. Fortunately, simple remedies are available from your chemist.