As the school year resumes, be on the lookout for head lice

Learn how to treat head lice and take preventative steps to help prevent future infestations.

Your child may bring home unwanted guests from school this fall. Head lice, or Pediculus humanus capitis, are parasitic insects that are found worldwide and have been around since pre-historic times. Wingless, they can move only by crawling and feed on human blood several times a day. Though most head lice live very close to the human scalp, occasionally they can be found in a person’s eyebrows or eye lashes.

What do head lice look like? There are three stages to the life cycle of head lice. First, lice eggs or nits are laid by an adult female at the base of a hair shaft very close to the scalp. The nits, which are very small and hard to see, hatch in 8-9 days into a nymph or immature louse. They look much like adult lice only smaller and must feed on blood to survive for 9-12 days before they fully mature into the adult stage. Even as an adult, the louse is only about the size of a sesame seed. Females are generally larger than males and are able to lay about six eggs daily. Adult lice can live about 30 days on a person’s head as long as they continue to feed several times a day on blood.

Head lice are spread primarily by direct head-to-head (hair-to-hair) contact with an infested person. The Centers for Disease Control and Prevention (CDC) estimate that every year in the United States alone, 6 million to 12 million children ages 3-11 experience an infestation of head lice. Children tend to make head-to-head contact in a variety of situations including school, day care, during sports activities, at playgrounds, during slumber parties, and at summer camps.

In a very few instances, head lice can be spread by coming in contact with clothing or personal item used by an infested person or by lying on a bed, couch, pillow, carpet or stuffed animal that was very recently in contact with an infested person. Nymphs can only live a few hours and adult lice a day or two without feeding on blood so it is not very likely that contact with these items will result in your contracting head lice. Nits, too, have a limited life span of less than a week if away from a human host and are not able to hatch if the temperature is lower than that of a human scalp.

How can you tell if you or a family member have head lice? Adult and nymph lice are very small, move quickly, and avoid light so they are often hard to find. You may wish to purchase and use a fine-toothed louse comb to find and dislodge nits from hair shafts. Nits are most often found in hair around the ears and near the back of the neck. Itching is the most common symptom occurring as an allergic reaction to head lice biting to feed on blood. Be aware that it may take 4-6 weeks for itching to appear if this is the first time a person has head lice or when the infestation is light. Other signs to look for include:

  • A tickling feeling or sensation of something moving in the hair
  • Irritability and sleeplessness as head lice are most active during the dark
  • Sores on the head caused by scratching…bacteria present on a person’s skin can cause some of these sores to become infected

What can you do to prevent and control the spread of head lice? It goes without saying that avoiding head-to-head (hair-to-hair) contact is highly recommended. As mentioned previously, do not share hats, scarves, coats, sports uniforms, hair ribbons, barrettes, combs, brushes, or towels. Combs and brushes can be disinfected by soaking in hot water (130 degrees Fahrenheit (F) or higher) for 5-10 minutes if you suspect they have been used by an infested person. Use hot water (130 degrees F or higher) to machine wash any clothing, bedding, and other items worn or used by an infested person, then dry them on high heat. Items that cannot be washed should be sealed in a plastic bag for two weeks or sent out for dry cleaning. You may wish to vacuum floors and furniture with which the infested person had contact although the chances of lice surviving for any length of time on these surfaces is not likely.

There are a variety of over-the-counter and prescription products that can be purchased to treat a person with an active infestation. As a precaution, you may wish to treat all household members and others who have been in close contact with that person. At a minimum, all these individuals should be checked for signs of head lice. In some instances a repeat treatment is needed. Read and follow directions carefully as some of these products are not recommended for use on very young children. If unsure whether the product is suitable for your child, or treatment is not effective, consult your health care provider.

Michigan State University Extension is another resource you may wish to consult to learn more about treating clothing and other items in your home should a family member experience an infestation of head lice. Their website contains articles on a wide variety of topics, contact information for local Extension offices, and a search feature to find an Extension expert who can assist with answering questions you may have.

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