What you need to know about lice

By October 17, 2016 May 1st, 2020 Health, Hygiene

With the end of summer and the start of the new school year, we usually see a spike in the number of head lice cases, so it’s always a good idea to go over some of the basics to help prevent and treat head lice.

Head lice occurs most commonly in preschool and elementary school-aged children, and recently we’ve seen an increase in the incidence of head lice in teenagers, putting their heads together for “selfies”.  In most cases head lice is transmitted by direct head-to-head contact with someone who has head lice.  Other risk factors may include:

  • Sharing clothing such hats, scarves, coats, sports uniforms or hair ties with someone who has an active infestation.
  • Using the same comb, brush or towels as someone who has an active infestation.
  • Lying down on the same bed, pillow, couch, or stuffed animal recently after someone with an active infestation.

The life cycle of the lice has three stages: egg, nymph and adult.

  • Eggs: These may also be called nits.  They are oval in shape and measure 0.8mm by 0.3mm in size.  They have a yellow or white colour and are often confused for dandruff or hair spray. They are laid by the adult female on the hair shaft closest to the scalp.  It takes between 6 to 9 days for the nits to hatch.
  • Nymphs: Once the nits hatch, they produce nymphs. The nit shell becomes more visible at this time, but remain attached to the hair shaft. The nymph looks like the adult louse, but is much smaller, approximately the size of a pinhead.  The nymph will mature to adult size approximately 7 days after hatching.
  • Adult: The adult louse is about the size of a sesame seed and has six legs, all with claws. They have a tan to gray-white colour, but may appear darker in individuals with darker hair. The female is larger than the male, and can lay upto 8 nits a day.  The adult louse can live 30 days on a person’s head, and about 1 or 2 days without a host.

Treatment of head lice is recommended in all persons with an active infestation.  All household members and close contacts should be checked and treated if an active infestation is suspected.  It is prudent that anybody who shares a bed with someone who has an active infestation is prophylactically treated.  All household members and close contacts who have an active infestation should be treated at the same time.

Treatments are available over-the-counter.  Most treatments will kill the adult lice, but have little effect on the nits.  These treatments will need to be repeated in approximately 7-9 days (this is the time it takes for the nits that were left behind by the first treatment to hatch and mature).  Some treatments have a stronger ability to kill the nits as well as the adult lice.  Retreatment with these options is only recommended if live lice can still be found in the hair several days after the initial treatment.

General Treatment Process:

  • Before applying treatment, remove clothing that may get wet or stained from the treatment.
  • Apply the treatment as per the instructions on the box. For longer hair, it may be necessary to use a second bottle.  Make sure to follow the instructions carefully to know how long the treatment should be left on before it is washed out, as this varies with different treatment options.

*** Warning: DO NOT use hair conditioner or combination shampoo-conditioner before applying treatment.  DO NOT re-wash hair for 1-2 days after treatment is complete***

  • Have the treated person put on fresh, clean clothes after treatment.
  • If after 8-12 hours live lice can still be found but are moving more slowly, retreatment is not required (it may just take the treatment longer to kill off all the lice).
  • If after 8-12 hours live lice can still be found that are as active as on initial finding, this may indicate that the lice is resistant to that specific treatment. Retreatment with a different ingredient is recommended in this case.
  • Nit combs should be used to remove nits and lice from the hair shaft following treatment and for 2-3 days after treatment.

Supplemental Measures:

  • Machine wash and dry clothing, bed linens, and other items that the infested person wore or used during the 2 days before treatment using the hot water and high heat. Clothing and items that are not washable can be dry-cleaned or sealed in a plastic bag and stored for 2 weeks.
  • Soak combs and brushes in hot water for 5–10 minutes.
  • Vacuum the floor and furniture, particularly where the infested person sat or lay. This will get rid of any fallen hair of the infested person that may still carry nits or lice.