A comprehensive history of why the heck humans get head lice.

Don’t you hate it when someone drops over without warning? That’s how I feel about head lice, who have been constant visitors at our place for more than two decades.

Just ask my five kids, they’ve all been through it (the common factor – their mum being in charge of treatment).

But just why do head lice love human hair so much? The answer lies in a bit of history and science, it would appear. Let’s investigate.

What are head lice?

Head lice go by the official name of Pediculus humanus capitis, and are also known as ‘heirloom parasites’.

They are wingless, six-clawed, white-brown or red-brown insects that spend their entire lives on the human scalp feeding exclusively on human blood. Like vampires, really.

Head lice are extremely fertile and one female can lay up to 120 eggs in her lifetime (and I thought five kids was a handful).

They live for approximately five weeks, so they’re mighty productive during that short time. It’s also difficult to kill all the eggs, and it just takes one to kick off another infestation.

Nits, which are actually the eggs of head lice, hatch just six to 10 days after being laid, and so the infestation continues.

If you think about it, our heads are their version of planet earth. Why, just the other day I saw a kids’ play adapted from Tristan Bancks’ Nit Boy book built exactly on this premise. It was funny, poignant and had me itching five minutes in.

When did humans first get head lice?

Head lice are called heirlooms because, like family treasures themselves, we pass them on. They’re part of our shared human inheritance and they go back as far as the 5th century AD.

Yes, scientists found mummified head lice on an ancient Egyptian nit comb. It's proof that scratching heads and nit denial goes back to The Nile.

But lice were around way before that. They are thought to have separated from body lice, a similar but distinct species around 100,000 years ago. Probably around the same time people began wearing clothing. Clearly some lice evolved to hand onto smoother fibres of fabrics and materials and others decided to remain on the scalp.

Head lice have even been immortalised in poetry tapping into grand themes of equality, like the 1786 poem by Scottish poet Robert Burns, To A Louse, On Seeing One on a Lady's Bonnet at Church.

It's exactly what it says - the narrator notices a lady in church with louse on her bonnet. The narrator scolds the louse for not realising how important the host is, then reflects on how we are all equal prey to lice.

Or perhaps he's just making fun of her. Either way, there's a lesson to be learned.

Why do we get head lice?

The weird thing about head lice is that as mundane as an infestation is (research suggests one-third of Australian primary school-aged children could currently have head lice), it carries the stigma of an STI. Although this is a HTI – a Hair Transmitted Insect.

The misconception is that head lice is a result of poor hygiene and is more prevalent in lower socio-economic groups. This isn’t true. Even The Queen can get head lice. And Princess Kate and dear little Prince George and Princess Charlotte.

If you’re ever feeling a bit average treating your kids’ hair for head lice, then just imagine the Palace dealing with the parasites! I’d love to see Kate in a plastic shower cap. Prince William doesn’t have to worry though, having hair is an infestation criteria.

Head lice are spread from head-to-head contact with infested persons and while they have been vectors for other disease transmission in Africa they don’t appear to do so in Europe, North America or here. Head lice grow to 2-3mm long and if they’re not attached to a human then they can’t live beyond three days. They literally die from homesickness.

They especially seem to love kids' hair. Kids put their heads together a lot more than adults do, so things like sharing hats, playing sport or taking selfies make them more susceptible. Selfie-born head lice – it's a thing.

How do we prevent head lice?

In our house, we don’t share hats. We have separate brushes and we colour code our towels in the bathroom so you know whose towel is whose.

Of course, if you do have lice make sure to wash your pillow cases in hot water because they can live up to three days without you, remember.

My family's favourite mode of protection is MOOV Head Lice Defence Spray. This Australian-made leave-in defence spray offers a simple family solution if you want to help prevent the infestation from spreading: if one person has lice, then it's best to use on EVERYONE in the family. Just find it in your local pharmacy.

So how does it actually work? Well, because we know that lice need to grip onto the hair shaft so they can lay eggs and move around the scalp, the spray coats the hair in a thin film that can deter lice over an eight-hour period. That's your day sorted.

It basically makes your head a very difficult place to navigate, and considering the life cycle lasts around 35 days, vigilant usage will have maximum benefit.

My 10-year-old daughter has hair down to her waist, and I'm happy to say nits haven't visited us since using MOOV Head Lice Defence Spray. Wham, bam, thank you m'am.

And finally, another way to get on top of unwelcome cranial visitors is to spread the word. That's right - don't be ashamed. Tell your school and your child’s friends if you find head lice.

There’s nothing to be embarrassed about and good communication is the key. Knowledge is power, and if you know there's an outbreak, you can do more things to prevent the spread.

We're all in this together - just as the ancient Egyptians were.

Have you had a head lice drama? Share below - it's OK, no shame.

*Always read the label. Follow the directions for use.