What do they look like?

Hair lice go through three stages in their short lives.

Eggs (nits): whitish-grey, tan, or yellow ovals the size of a grain of sand. They look like dandruff and stick close to the scalp for nine or 10 days before hatching.

Nymphs (baby lice): smaller versions of adult lice

Adults: the size of a sesame seed, grey-brown in colour, and difficult to spot. They can survive 30 days on someone's head but usually died within three days away from a scalp.

How do they spread?

Direct hair-to-hair contact and shared items that include hats, combs, brushes, and headphones.

They are common on young and school-aged children. Among youngsters, head lice is the second most common communicable ailment next to the common cold.

Head lice feed on blood. They crawl quickly but do not fly or jump. A louse that lives on a person cannot be found on an animal.

What are the symptoms?

An itchy scalp is usually the first sign. But some people have no symptoms.

Concerned parents should immediately check their child's hair for eggs and follow up after one and two weeks. Use good lighting (and a magnifying glass), and part the hair in small sections across their head, looking closely at the scalp.

For lice, look close to the scalp, around the crown, behind the ears, and at the bottom of the neck. Also take note of red scabs caused by lice, eggs, and scratching.

In general, parents should check their children on a weekly basis as a precaution.

What is the treatment?

First, check other family members and contact the child's school and other activities (sports, play groups, etc).

Second, consult your doctor about potential allergic reactions or if the symptoms appear serious.

Three chemicals found in non-prescription shampoos and creams are approved in Canada for head lice treatment: pyrethrin, permethrin, and lindane (which can be toxic and should not be used on children under two). Consult a pharmacist for the best choice.

Rinse the hair with cool water after the treatment, and repeat seven to 10 days later. Call your doctor if live lice are visible 48 hours after the second treatment.

Nit removal is also necessary after each treatment. Use a special fine-toothed comb or fingernails, and pull the nits from the roots right down to the tips.

But some experts do not believe pesticides are a safe or effective option. A non-insecticidal product (Resultz) is also available but is only recommended for children above four.

Are there alternative treatments?

People have also used home remedies: mayonnaise, petroleum jelly, olive oil, vinegar, or margarine. But these are unlikely to actually kill the lice. Experts do not believe wet combing, tea tree oil, hair dye, conditioner, or aromatherapy will provide successful treatment.

The City of Ottawa has posted another treatment developed by a doctor at the Hospital for Sick Children in Toronto:

"Mix a solution of 50% mineral oil (less odour than vegetable oil) and 50% white vinegar.

Test the mixture for skin sensitivity by applying it to a small patch of skin on the arm and observing it for 15 minutes.

Soak the hair with solution and cover it with plastic for approximately one hour. Plastic can cause suffocation. Do not leave your child unattended.

Thoroughly rinse the hair with several applications of regular shampoo. Do not use conditioner or a shampoo that contains conditioner.

Make sure the mixture does not get into the eyes. If it does, wash the eyes with plain water for 2-5 minutes.

Use a comb soaked in vinegar to remove the nits from the hair shafts.

This treatment may be repeated whenever necessary as side effects are unlikely.

The theory is that the vinegar loosens the nits from the hair shaft, and the oil helps with combing out the nits as well as suffocating any live lice that may be present."

What about hats or pillowcases?

Place dryable items in a hot dryer for 20 to 30 minutes. Vacuum items that can't be dried. Or, set it aside for one to two days. Lice die within 24 to 48 hours without feeding on blood.

Sources: City of Ottawa, Canadian Paediatric Society, The Lice Squad