What are head lice?
Head lice, or Pediculus humanus capitis, are tiny crawling insects that live on the human scalp. They are parasites that survive by sucking small amounts of blood from the head. Head lice cannot live more than 24 hours off their human host.
Life-cycle: The louse (singular of lice) attaches its eggs, otherwise known as nits, to the base of a hair shaft. It takes 8-10 days for an egg, from an inseminated female, to hatch and 9-12 days for a nymph to grow to adult size. A female louse may lay up to 3-6 eggs per day.
What do head lice look like?
An adult louse is wingless, has 6 legs, and ranges in color from reddish brown to gray. Lice have claws to grasp the hair and cannot jump, hop or fly. A nit is a small yellowish-white, oval shaped egg that sits to the side of a hair shaft glued at an angle.
Below is a picture of head lice from the CDC (Center for Disease Control) web site. It shows lice in their 3 phases: egg (nit), nymph (young louse) and an adult louse.
What are the symptoms of head lice?
The most common symptom is a persistent itching of the scalp particularly around the ears, back of the neck and crown. However, some people do not experience any itching at all. If you or someone in your household has these symptoms, it is recommended that you do a visual check of the hair to confirm the presence of head lice and nits.
What is the best way to look for them?
Although head lice can be seen with the naked eye it is best to use a bright light and magnifying glass to search for them. Nits, which are very small and almost transparent, can be seen all through the hair.
How are lice transmitted?
Lice are very contagious and are primarily spread by head to head contact.
Are lice dangerous?
Lice are more of a nuisance or annoyance than a public health risk. They are not known to transmit diseases. Excessive scratching may cause irritation which results in an infected scalp. This is why treatment should begin as soon as possible.
Are there any other risks?
Another risk associated with lice is related to their treatment. According to Dr. Richard Pollack of the Harvard Public Health Institute “The greatest harm associated with head lice results from the well-intentioned but misguided use of caustic or toxic substances to eliminate the lice.”
In other words, it’s important to learn as much as you can about treating head lice before you treat your child or other loved one.
Don’t make the cure worse than the disease.
Sources and links for additional information
HeadliceInfo.com – The American Headlice Information Center
Center for Disease Control – Division of Parasite Diseases
Kids Health – Nemours Foundation
Mayo Foundation for Medical Education and Research – Lice Information
National Pediculosis Association®