What are head lice?
Head lice are small, parasitic insects that live on the human scalp and hair. They are wingless, but have six feet specially evolved to grasp onto the hair shaft. Head lice can be difficult to see in the hair as they vary in colour from skin-tone to brown. Head lice feed on human blood from biting the scalp.

How are eggs (nits) different from head lice?
Eggs (nits) hatch about 7 to 10 days after being laid and can be easier to see than the lice themselves. Eggs are about the size of grains of salt and feel gritty to the touch when fingers are run though the hair. Eggs can be found glued to the hair shaft near the scalp (eggs found further along the hair shaft are probably old, hatched, or dead).

How do you detect head lice?
An itchy scalp is a frequent symptom of head lice – but not all people who have head lice actually feel an itch. The white eggs (nits) are easier to spot than live lice. Eggs are about the size of grains of salt and feel gritty to the touch when fingers are run through the hair.

The lice bite the scalp to suck blood every 4 to 5 hours. The biting is particularly irritating to children, and causes the characteristic scratching which is often the only sign of infestation. Once the lice bite enough to cause noticeable scratching, the infestation is usually well established. Adults are often desensitised and can carry head lice without realising it.

Head lice lifecycle
During their lifetime, head lice can lay up to 200 eggs (nits) which they glue to the hair shaft with a special and very strong ‘cement’. The eggs remain glued to the hair until they hatch and are found further along the hair as the hair grows. The egg will hatch approximately 10 days after it was laid.

The young louse reaches maturity after 7 – 10 days and can then start to lay eggs of its own. Head lice have a life span of around 40 days.

How are head lice transmitted?
Head lice are most commonly transmitted by head to head contact, for example, when children are playing with each other and are ‘sticking their heads’ together. Head lice can also be transmitted if children are sharing combs, brushes, hats, caps or scarves. Head lice live only on human beings. They cannot reproduce on animals or in bedding or carpets. They need a frequent supply of blood and body heat generated from the scalp to survive.

Resistance to chemicals
Recent international research has shown that head lice can rapidly develop a resistance against chemicals in conventional head lice treatments, which means that these insecticides become less effective. Chemical treatments can also lead to skin irritation or allergic reactions, and the side-effects of chemical treatments have not yet been fully explored.

Easy precautionary measures
Do not let kids share brushes, combs, hats or caps! Keep long hair tied back or braided. Check for head lice regularly if there is any head lice alert in the local area. If one family member has head lice, check all other family members for head lice too!