Lice are six-legged parasites that are becoming increasingly resistant to shampoos and over the counter treatments. Spread from student to student as they huddle over their phones and iPads, lice are resurgent as a major American health problem.
Chances are that "nitpicker" isn't a career possibility you explored with your high school guidance counselor. Removing lice the old-fashioned way, by combing them out of the hair, has nonetheless become a growth industry in the United States as a problem that used to be short-term and rare has become chronic and common.
As shampoos stop working and schools allow lice-infested students to attend classes rather than requiring them to stay at home, more and more children and teens--the American Pediculosis Association estimates 12 million children every year--are coming down with infestations of the creepy crawly insects. One famous nitpicker, Lauren Salzberg, also known as The Potomac Lice Lady, sees clients in her office in her stately suburban Washington, D.C., from as far away as Atlanta, and professionals like her are popping up all over the United States. When some people come in to see professional nitpickers, they are panicked. Most of them are itchy.
What Are Lice, and What Is Lice Infestation?
Lice are one of the oldest human health problems. Archaeologists have found fossilized louse eggs that are 10,000 years old. Humans have been dealing with lice for so long that references to lice are even part of the language in words and terms such as "lousy," "nitpicking," and "going over things with a fine-toothed comb."
A louse (plural, lice) is a tiny parasite that lives on human skin, especially in hairy areas. Lice do not infest any organisms other than humans, and you can't catch lice from or give lice to your pets, although chimpanzees are susceptible to a closely related species. This wingless insect is no more than about 2 to 3 mm long even as an adult, unable to fly or hop, forced to crawl from one place to another. There are several species of lice, Pediculus capitis (lice on the head, common among children), Pediculus corporis (body lice, especially on arm pits), and Pthirus pubis (pubic lice, often called “crabs”).
Body lice can lay their eggs in the seams of clothing, but head and pubic lice lay their eggs at the bases of hair shafts. A female louse lays about 10 eggs a day, gluing them in place on clothing or on the skin. The baby lice called nits hatch in 8 or 9 days and mature in another 10 to 12 days. Adult lice live about 30 days if they are able to stay on the human body, but they die in just 1 or 2 days if they are deprived of contact with their human hosts.
Lice feed on human blood. Approximately five times a day they attach themselves to the skin with hooklets on their six legs. Their mouth parts retract into their bodies when they are not drinking blood. Lice digest blood slowly enough that lice have been used to identify victims and assailants in crime scene investigations.
Lice infestations usually consist of just 10 adult female lice, although up to 1000 of the insects have been removed from heavily infested people. The presence of these tiny insects is not benign. Their bites trigger itchy, sometimes painful allergic reactions. Head lice do not carry other infectious diseases, but body lice can spread R. prowazeki, which causes typhus; B. quintana, which causes trench fever; and B. recurrentis, which causes relapsing fever.
About 30 percent of people who have pubic lice also have a sexually transmitted disease such as gonorrhea, chlamydia, syphilis, or HIV.
How Common are Head Lice? And Who Gets Them?
Just how common are lice infestations? School surveys have found head lice infestations in:
- Up to 4 percent of children in schools in Mali.
- Up to 8 percent of children in schools in Saudi Arabia.
- Up to 9 percent of children in schools in Belgium.
- Up to 31 percent of students of schools in the UK.
- Up to 59 percent of students in schools in Turkey, and
- Up to 61 percent of students in schools in the United States, where no-nit policies result in 24,000,000 absences from school every year.
Head lice are more likely to affect girls than boys (since girls have longer hair). They are more likely to affect whites and Asians (due to the shape of the hair shaft).
What You Can Do About Lice
The first thing to do when you hear about lice in your children's school (or someone with whom you are intimate informs you that you have crabs) is to stop their spread. Doing this, of course, requires knowing how these tiny parasites move from person to person.
How Do Lice Spread from Person to Person?
Different species of lice spread in different ways.
- Head lice most often spread by direct contact or by air flow. Among small children (especially in damp, overheated classrooms) they spread from child to child by skin-to-skin contact. They can also be spread by sharing hats, caps, combs, scarves, pullovers, coats, or bedding. Lice can be spread from person to person while blow drying hair. Head lice can also crawl from place to place at a rate of about 2/3 of a foot (22 to 24 cm) a minute, although they have trouble attaching their feet to leather, plastic, or other smooth surfaces. Head lice are most common during warm, humid weather, and among children aged 3 to 13.
- Body lice are spread by direct skin to skin contact or by sharing clothing, towels, or bedding. Body lice are most common during cold weather, and among homeless people.
- Pubic lice are spread during sexual intercourse, and in shared bedding. Children who have pubic lice have not necessarily been sexually molested. They can contract the lice by sleeping in their parents' bed. Pubic lice are most common among adults who have multiple sex partners.
What to Do Next When You Have Head Lice
Once you know where the lice are coming from, and you stop their spread, then you can take concrete steps to get rid of them.
- The first step in controlling head lice is to kill as many as you can. This means putting all recently worn clothes in the washer and then drying them in a clothes dryer for at least 45 minutes. Washing, soaking, or drying items at a temperature greater than 130°F (55°C) can kill both head lice and nits. Items that can't be heated in the drier should be wrapped in plastic for at least 48 hours. This starves the lice in upholstery and non-washable clothing. Dry cleaning also kills lice.
- The second step in controlling head lice is to remove as many as possible from infested skin by combing them out. Manual removal is always necessary to get rid of lice for good. Comb the hair with a fine-toothed comb, emptying the comb after each pass of the hair onto white paper or plastic that you later throw away. Shake the comb clean before making another pass through the hair, removing lice each time. Then discard the paper or plastic and the lice into the trash. Don't leave it out, allowing the lice to escape.
- Repeat the process every day for 7 to 10 days. Use anti-lice shampoos every day, but don't rely on shampoo or ointments to do all the work.
- Be aware that alcohol-based shampoos (Ulesfia) dry out the scalp if they are used every day. If the scalp is not thoroughly rinsed after using the shampoo, itch and irritation can actually get worse. Malathion-based shampoos (Ovide) are inherently toxic to humans as well as to lice, although they do get rid of the infection. A better option is a non-toxic silicone shampoo called dimethicone, available in Europe and Canada but not in the United States.
- Araujo A, Ferreira LF, Guidon N, et al. Ten thousand years of head lice infection. Parasitol Today. 2000 Jul. 16(7):269.
- Walsh J, Nicholson A. Head lice in children--a modern pandemic. Ir Med J. 2005 May. 98(5):156-7.
- Photo courtesy of Gilles San Martin: https://www.flickr.com/photos/sanmartin/4900275659/ and https://www.flickr.com/photos/sanmartin/4900274585/
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