HEAD lice - or nits, as every schoolchild refers to them - are more common than ever, despite all the advances in modern medicine.

Experts says there are even more of the tiny creatures around, and a recent survey revealed one primary school child in five was a sufferer last year.

But what exactly are head lice?

Firstly, they are irritating, but they are not a health hazard - they don't spread disease

Contrary to popular myth, head lice don't differentiate between dirty and clean hair

Age-old remedies range from Vaseline to meths

The fashion for using soft, spongy hairbrushes rather than traditional combs may be a factor in their proliferation

People spend nearly £200million a year on trying to find an effective treatment

A victim can be affected more than once, particularly if a particularly virulent strain spreads through a school

Head lice can't survive without a supply of blood - so there is no need to treat clothing or bedding

Children cannot catch them from family pets.