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University of Nebraska–Lincoln

UNL Extension in Lancaster County

Insects, Spiders, Mice & More

Helping Nebraskans enhance their lives through research-based education.

Head Lice Adults and Nit

Fig 1.

Managing Head Lice Safely

by Barb Ogg, PhD, Extension Educator

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The Problem

There are 6–12 million cases of head lice in the United States each year and are found in children belonging to all socioeconomic levels. Increased recent head lice infestations are probably related to head lice resistance to over-the-counter products, like NIX®, RID®, A-200®, Clear® and store brands with similar active ingredients (pyrethrins, pyrethroids). Pyrethroid products have been used widely for more than 30 years and were initially very effective. In 1999, a Harvard researcher found significant resistance in U.S. head lice. Other research has confirmed resistance in the United States and other countries where pyrethroid products have been used for many years.

The bottom line: these products are not going to work very well and are unlikely to eliminate all head lice, even when used as directed on the label. Despite their lack of effectiveness, pyrethroid products are still being manufactured, sold and used by parents who don't realize these will not solve their child's lice problem.

Head Lice (Louse) Egg (Nit)

Fig. 2

Please read No Nit Policies Discouraged in Schools


Biology:


Head lice are small, tan to brown-colored insects (Figure 1). Lice are found close to the scalp and must feed frequently on blood. Eggs laid by adult female lice are glued to strands of hair about 1/4-inch from the scalp. Eggs hatch in 7–10 days. After hatching, the eggshell (nit) remains firmly attached to the hairshaft. This glue is so strong, nits cannot be easily removed. Researchers have found the glue is chemically similar to components in human hair, which makes it difficult to develop a safe solvent to aid in nit removal.

A viable egg (which will hatch) is brown (Figure 2) because there is a developing louse inside the egg. Once the egg hatches, the eggshell (still attached to the hairshaft) will be white, but at this time, there is no living louse inside the egg (Figure 3).

Nits stay attached to  the hair shaft even after hatching.

Fig. 3

Head lice cannot fly or hop like fleas, but they can crawl quickly through the hair at a rate of 9 inches per minute.

An adult female head louse lays an average of six to seven eggs per day and the average life span is about 32 days. Immature lice pass through three stages before becoming adults, which takes another eight to nine days. One pregnant adult female can produce enough offspring so a significant infestation can occur within a month. A child having a significant infestation has been infested for at least a month or more. People are most contagious when they have adult lice on their head. A newly-hatched nymph rarely leaves the head.

Head lice require warm, humid environment of the human scalp for survival. They feed frequently and quickly become dehydrated if they fall off their host. It is unlikely head lice will survive more than 24-hours after falling off their host.

Only a live louse defines an infestation. No treatments should be done unless live lice have been found.

Inspection:


Look for signs of head lice by examining all areas of the scalp. Look for live lice and/or eggs.

Fig. 4

If a child is scratching his/her head or if there has been a report of head lice in a classroom or play group, look for signs of head lice (Figure 4).

  • Feces — Look for lice feces on the scalp, which are tiny black specks. If you see them, examine the rest of the head for live lice.

  • Eggs — Female lice typically attach eggs 1/4-inch from the scalp. There can be from a few to several hundred nits in a child’s hair. Use a magnifying glass and a good light to help distinguish between nits and dandruff. Eggs are oval-shaped and glued securely to only one side of the hair shaft. The nit stays attached to the hair shaft even after hatching or if it dies. Eggs are often found above the ears or at the nape of the neck, but can be anywhere.

  • Live lice — Part the hair with a rat-tailed comb. Check all areas of your child’s scalp, especially at the nape of the neck and around the ears; these are favorite spots for lice. But, also check the crown and other areas. Studies have shown even trained professionals often miss live lice because immature lice are so small and hard to see. It is important to remove even the tiniest lice.
Robi Comb

Use an Electronic Comb to Detect/Remove Live Lice

There is an electronic comb on the market, called the Robi Comb™ (manufactured by LiceGuard™) which will detect live head lice. It runs on one AA battery. When turned on, it emits a high pitched hum. If lice are caught between the tines of the comb, the humming stops (Figures 5 and 6). We have used this comb and have found it to capture even the tiniest lice. When the humming stops, check the electronic comb for lice and check the hair for live lice. This comb will not detect eggs.

The manufacturer claims lice trapped in the teeth are electrocuted, but we have not always found this to be true. The electronic comb should only be used on dry hair. Avoid direct contact with ears, eyes and mouth. Be sure to read and follow directions for safe use of this comb.

Robi Comb with louse caught

Use an electronic comb every two days. Remove all lice detected by the comb and within two weeks all hatching should be complete. Without adult lice, egg laying cannot take place. This comb can be used as a monitoring tool on dry hair following insecticidal treatments to make sure live lice have been eliminated. The cost of this comb is about $30; it can be found at many pharmacies or over the Internet.

Combing with a Nit Comb

This is the oldest method of lice control; it is inexpensive and completely safe (Figure 7). When done properly, it takes time and requires patience on the part of parent and child. A 2005 study published in the British Medical Journal, showed wet combing; using a fine-toothed nit comb after lubricating hair with conditioner, was more effective than pyrethroid or malathion treatments.

Insecticidal Treatments

To reduce the number of live lice on your child’s head, the following insecticidal treatments are available for treating head lice.

Over-the-Counter Products:

  • Pyrethrins (permethrin): (Products: Nix, Rid, A-200, Pronto and others) When used correctly, these over-the-counter products are pretty safe; only a few children will exhibit minor problems such as itching, a minor rash or an allergic reaction. But, recent studies have shown only 40% of lice will be killed, even when two treatments are used. Some manufacturers provide combs with their product and direct parents to comb to remove nits/lice not killed by the treatment.

  • Sodium Chloride: (Product: LiceFreee®) Researchers who have looked at this product did not find it to be effective. Because this product is considered to be a non-pesticidal product, the manufacturer does not have to provide data to the FDA to show it is effective.

Prescription Medications (In order of when they were approved by FDA):

  • Malathion (0.5%): (Product: Ovide®). Malathion was used in European countries for many years before it became available in the United States in 1999. It should not be used on children under six years of age. Malathion is an organophosphate insecticide. This prescription product has an unpleasant odor and is flammable. But, the biggest drawback to using this product is the way it is to be used. Label directions say to apply the lotion to hair for 8–10 hours before rinsing it out. Some studies have shown there is efficacy for reduced treatment time, but parents are always taking a chance it won’t be 100% effective when they don’t follow treatment directions. So far, head lice have not been shown to be resistant to malathion in the United States.

  • Benzyl alcohol (5%). Product Ulesfia®) was approved by FDA in 2009. It kills lice, but not eggs, so a second treatment may be needed seven days after first treatment to kill hatched nymphs. Ulesfia lotion is to be applied to dry hair, saturating the hair and scalp. Manufacturer guidelines for the amount of Ulesfia needed is based on the child’s hair length. After 10 minutes, the lotion should be rinsed off with water. The hair may be shampooed immediately after the lotion has been rinsed off. Directions recommend use of a nit comb to remove nits. A clinical study showed 76.2% of subjects after treated with the benzyl alcohol lotion were lice-free two weeks after last treatment.

  • Spinosad (0.9%). Product: Natroba®) was approved by FDA for head lice in 2011 for the treatment of children four years of age and older. The active ingredient, spinosad, is a chemical derived from bacteria found in soil collected inside an abandoned rum distillery on the Virgin Island. It is a topical suspension treatment to be applied to the head for 10 minutes and washed out. A second treatment will be necessary if live lice are observed seven days after the first treatment. In two clinical trials, 86% of children were lice free after one or two Natroba treatments.

  • Ivermectin (0.5%): (Product: Sklice®) Sklice was approved for use in 2012 by FDA against head lice. It is a one-time use topical lotion. It is expensive and insurance companies may not cover the cost. Results of a study published in New England Journal of Medicine: on day two after a single application, 94.9% of subjects were lice free, but after 15 days, only 74.8% of them were lice free. This suggests eggs were not controlled by the one-time treatment.

Not Recommended

Lindane: Lindane is an organochlorine insecticide. It has been used in the United States for lice for 60 years or more. Head lice have been shown to be resistant to lindane so its effectiveness is questionable. The American Academy of Pediatrics (AAP) no longer recommends it as a pediculocide. Although lindane shampoo 1% is approved by the FDA, overuse or misuse can cause neurotoxic reactions, so its use has been discouraged. Because of these adverse effects, we don’t recommend lindane.

Alternative Treatments

In an effort to find an easy, safe treatment, many parents seek alternative treatments, like mayonnaise, olive oil, vinegar, essential oils, enzymes and combinations. Anecdotal reports are abundant on the internet and sometimes even medical personnel are persuaded these inexpensive home remedies will be effective. But, studies have shown lice can survive in hair covered with olive oil, mayonnaise and even petroleum jelly — even when it is left on the hair overnight. These alternative treatments have no scientific basis for treatment.

Shampooing with ordinary shampoo won’t kill lice. Lice can survive through two consecutive shampooings, even when the hair is not rinsed for an hour after the second shampooing. Lice don’t drown easily. Research has shown lice can survive when immersed in water for 14 hours at 86–98°F. There are no special shampoos which will prevent lice.

Aerosols and Sprays

Parents who look at head lice products in the drugstore, often see aerosols being sold there. But these products are unnecessary because live head lice are unlikely to survive after 24-hours on environmental surfaces. Likelihood of killing lice with these products is so low it doesn’t justify expense of these pesticides. It also doesn’t make sense in hiring a pest control company in schools, childcare facilities or homes. Environmental treatments are not recommended. Use a vacuum cleaner instead.

Desiccation Device

The LouseBuster® is a custom-made, hot-air blower, designed to maintain a controlled temperature (138°F) and airflow greater than a standard blow dryer. One study showed 94.8% mortality of eggs and lice after one 30-minute treatment of hot air. Head lice and eggs were collected from hair after treatment and evaluated for mortality. Researchers found dead lice on subjects’ smocks and drop clothes, apparently blown out of hair. This research study was peer reviewed but conducted by researchers with a potential conflict of interest as they were the developers of this device. The LouseBuster costs $2,000–$2,500 and requires special training to operate.

About Re-infestations

Sometimes parents have used head lice products and combed, only to find their child has another head lice infestation. Sometimes, their child did not become re-infested from other children; instead, the parents likely did not completely eliminate the lice with the initial treatment. Missing just a few tiny lice will be enough to restart the infestation.

To prevent re-infestation, continue to examine all family members, including parents, and treat only if live lice are found. It may be helpful to use an electronic comb periodically to check for live lice.

Laundering

Because head lice do not survive long off the host, they are not likely to be found on bedding or clothing. But, you can kill lice by laundering washable items in hot, soapy water in a washing machine. They will also die if heated in a hot dryer for 30 minutes. If time is limited, it is more beneficial to spend time removing lice from the child’s head, rather than laundering, vacuuming or other cleaning activities. Items such as stuffed animals and pillows which are not washable can be heated in a dryer.

Combs and Brushes

Some studies have shown lice are not dislodged by the use of regular combs and brushes, but it is good to be cautious when lice are a problem. Instruct children not to share combs, brushes, hats or other articles of clothing at school, play or other activities.

Cutting Hair

Children with long, hanging hair will probably get lice more often than children with short hair because lice have claws which help them grasp and quickly climb up hair from an infested child to another. For children with repeated infestations of head lice, a short, stylish hair style may make inspecting and combing easier. Pulling hair back into a pony tail may be helpful in reducing risk of transfer.

Focus your control efforts on combing to eliminate lice.


When combing, hold the mass of hair with one hand.  With the other hand, hold the lice 
      comb in a slanting position with the teeth toward the head

Fig. 7

Combing: a Safe, Non-toxic Method of Lice Control

1. Getting ready--You Will Need:

  • fine-toothed comb designed for nit removal. A metal comb is less flexible than plastic ones and may be more effective at removing nits.
  • bobby pins or hair clips (for long hair)
  • a large towel to place around the child’s shoulders during combing
  • box of facial tissue
  • wide bowl of water with a squirt of dishwashing liquid

Note: Combing should be done in a well-lighted area. Seat the child so her/his head is just below eye level. It might be a good idea to have something fun to entertain the child that does not require much physical activity. Consider reading, modeling clay, coloring or games/videos/dvd.

2. Preparing the hair--Cover the hair with any type of salad oil or conditioner to keep the hair wet so combing is easier. Remove tangles with a regular hair comb.

3. Combing--Separate a mass of hair about the width of the metal lice comb. It is important to separate the hair into small sections so you can more easily see lice and nits.

Hold the mass of hair with one hand. Insert the lice comb as close to the scalp as possible and gently pull the comb slowly through the hair several times. Check the hair carefully. Comb one section at a time and check each section again (Figure 6). Pin the hair in a curl flat against the head.

Dip the comb in the soapy water and use the tissue to remove lice and debris. Make sure the comb is clean before you use it on the hair again. Continue combing.

4. Cleaning Up--Flush the contents of the bowl down the toilet. Shampoo the hair at least twice to remove the oil. When the hair is dry, check for stray nits and remove those hairs individually with a pair of small, pointed scissors.

It is VERY important to remove all of the eggs (nits). Soak the lice comb for 15 minutes in hot ammonia water (1 tsp ammonia to 2 cups hot water). Or, boil the metal comb in plain water for 15 minutes. Use an old toothbrush to clean the comb. The comb can now be used on another family member.


Focus your control efforts on combing to eliminate lice.


When combing, hold the mass of hair with one hand.  With the other hand, hold the lice 
      comb in a slanting position with the teeth toward the head

Fig. 7

Combing: a Safe, Non-toxic Method of Lice Control

1. Getting ready--You Will Need:

  • fine-toothed comb designed for nit removal. A metal comb is less flexible than plastic ones and may be more effective at removing nits.
  • bobby pins or hair clips (for long hair)
  • a large towel to place around the child’s shoulders during combing
  • box of facial tissue
  • wide bowl of water with a squirt of dishwashing liquid

Note: Combing should be done in a well-lighted area. Seat the child so her/his head is just below eye level. It might be a good idea to have something fun to entertain the child that does not require much physical activity. Consider reading, modeling clay, coloring or games/videos/dvd.

2. Preparing the hair--Cover the hair with any type of salad oil or conditioner to keep the hair wet so combing is easier. Remove tangles with a regular hair comb.

3. Combing--Separate a mass of hair about the width of the metal lice comb. It is important to separate the hair into small sections so you can more easily see lice and nits.

Hold the mass of hair with one hand. Insert the lice comb as close to the scalp as possible and gently pull the comb slowly through the hair several times. Check the hair carefully. Comb one section at a time and check each section again (Figure 6). Pin the hair in a curl flat against the head.

Dip the comb in the soapy water and use the tissue to remove lice and debris. Make sure the comb is clean before you use it on the hair again. Continue combing.

4. Cleaning Up--Flush the contents of the bowl down the toilet. Shampoo the hair at least twice to remove the oil. When the hair is dry, check for stray nits and remove those hairs individually with a pair of small, pointed scissors.

It is VERY important to remove all of the eggs (nits). Soak the lice comb for 15 minutes in hot ammonia water (1 tsp ammonia to 2 cups hot water). Or, boil the metal comb in plain water for 15 minutes. Use an old toothbrush to clean the comb. The comb can now be used on another family member.


Head Lice FAQ's:


Q. Why do I have more lice problems with my daughter who has the longest hair? I have two other daughters and one son.

A. Loose long hair is more likely to come into contact with lice than short hair. It is also more difficult to inspect, treat and comb a person who has long hair, so managing a lice infestation is more difficult. Hanging hair is a liability. Putting your child's hair up in a ponytail or bun will be helpful or work with your daughter to choose a new, shorter hair style. For some inexplicable reason, lice seem to survive or be attracted to some people more than others and some children in the family are more likely to get lice than others.


Q. Can we get head lice from our pets? Do we need to treat our pets?

A. Humans are the only hosts for head lice, body lice and crab lice. Other closely related lice infest monkeys or apes, but not dogs, cats, rodents or birds. Many animal species have their own compliment of lice that cannot infest humans. You don't need to treat your pets for human lice.


Head Lice (Louse) Egg (Nit) with dead Head Louse (Lice) embryo
Figure 8. Head lice egg with dead embryo

Q. I am having a hard time knowing what nits look like. And, how would I know if nits are alive, dead or hatched?

A. Nits are laid on the hair and glued to one side of the hair shaft. They are usually laid on single strands of hair, close to the scalp, but not on it. Nits are not round, but oval. They are light-colored when first laid (yellowish or gray), but darken to a tan or coffee color as the embryo develops. Once the egg hatches, the spent shell (the nit) remains attached to the hair shaft, but it is white. As the hair grows, the nit grows with it and is farther from the scalp. Without the aid of a microscope or magnifying glass, it is hard to tell if the nit is alive, dead or hatched.


Q. My doctor didn't recognize head lice even though my daughter had sores from scratching her head. He said that she had "winter itch" How can doctors miss this?

Q. My school nurse and after school daycare provider say my daughter has head lice nits in her hair. I see small white round things that seem to be attached to the hair shaft. But nobody, including me, can see any live lice at all. What could be going on?

A. The possibility for both of these parents is their children are being incorrectly diagnosed. Studies have shown that some health care workers sometimes misdiagnose head lice infestations, both by declaring lice were present when they weren't (false positive) and by not finding lice when they were there (a false negative). It is difficult for even well-trained individuals to correctly diagnose the difference between dead nits and live nits. Figure 8 shows what an egg with a dead embryo looks like. Compare it with Figure 2.

There are obvious problems when children are not diagnosed properly. When lice are under-diagnosed, contagious children may spread lice to others. When lice are over-diagnosed, children may be over-treated with lice products and parents are frustrated. The message here is that, unless you see live lice (ones that move) or brown nits, the child may not be infested at all. Be cautious before you come to that conclusion though. . .it can be difficult to detect an infestation of only a couple lice and tiny ones are very hard to see.

A very helpful way to check for live lice is an electronic comb, like the Robi Comb™. Although it doesn't detect nits, it can detect even the tiniest lice before they grow to adults and lay eggs. Combing will still be needed to remove nits.


Q. I am pregnant and my child has head lice. I am concerned about exposure to any insecticides. What should I do?

A. If you are pregnant or nursing, contact your physician before using any insecticidal products on yourself or your child. Remember, you can completely avoid insecticide shampoos/rinses if you comb the hair (using oil or conditioner) to remove lice and nits, but you must be diligent.


Q. I carpool and have transported children with head lice. How do I treat the vehicle?

A. It is not likely that lice will end up on car seats and upholstery. Surface sprays are not recommended because insecticidal sprays marketed for treating lice can cause allergic reactions for people who have allergies or respiratory problems. If you want to take some action, vacuuming seats will be as effective as treating with a chemical.


Q. Some of my students have head lice. Should I ask to have my classroom sprayed with insecticides?

A. School classrooms should NEVER be sprayed for lice. An Australian study was conducted in a school where head lice were found on more than 21 percent of the children. Floors were vacuumed with a filter designed to catch lice, but, even with the abundance of infested children in the school, researchers did not find any lice on floors. These results suggest few lice fall off the host and environmental treatments are mostly a waste of time and money.


Additional Resources:

"Removing Head Lice Safely," an eight-minute DVD/video demonstrating head lice management in an easy-to-understand format. The video features highly-magnified live lice, a combing demonstration on a child and actions to help prevent re-infestations. The video and accompanying materials were developed by the University of Nebraska-Lincoln Extension and State of Nebraska Department of Health and Human Services. These videos are available in English, Spanish, Arabic and Russian languages. English, Spanish and Arabic can be viewed on-line FREE.

New ResourceOrdering "Removing Head Lice Safely": English, Spanish, Arabic and Russian language versions of "Removing Head Lice Safely" now all available on one DVD for $10. This Telly Award-winning series also includes the Quick Guide to Removing Head Lice Safely with step-by-step instructions for proper combing". You can still purchase the popular Videotapes for $3 each in a variety of languages and formats. Discounts on orders of 10 or more DVD's and/or videotapes to the same address. Brochure and Details

"Quick Guide for Removing Head Lice Safely," an educational resource guide which provides, practical, simple directions on head lice control for families. Available in English, Spanish, Arabic Languages.

Head Lice Resource You Can Trust Web site - University of Nebraska-Lincoln Extension in Lancaster County. Photos, video, educational resources.

UNL Extensions Integrated Pest Management (IPM) in Schools Web site provides low-toxic methods of controlling pests in schools.

References:

Photo Credits:

  • Figure 1. Adult head lice are 1/10–1/8” long and are tan to grayish-white (highly magnified view). Photo by Barb Ogg
  • Figure 2. Eggs are glued to hair strands about 1/2-inch from the scalp (highly magnified view). Photo by Jim Kalisch, UNL Department of Entomology
  • Figure 3. Nits stay attached to the hair shaft even after hatching (highly magnified view). Photo by Barb Ogg
  • Figure 4. Look for signs of head lice by examining all areas of the scalp. Look for live lice and/or eggs. Photo by Barb Ogg
  • Figure 5. An electronic comb can be used for detecting and removing live lice. Photo by Vicki Jedlicka, UNL Extension in Lancaster County
  • Figure 6. An adult louse caught in an electronic comb. Photo by Barb Ogg
  • Figure 7. When combing, hold the mass of hair with one hand. With the other hand, hold the lice comb in a slanting position with the teeth toward the head. Photo by Barb Ogg
  • Figure 8. Nit with Dead Embryo: Credit. James Kalisch, UNL Department of Entomology

Educational ResourcesReturn for More Head Lice Educational Resource

The information on this Web site was updated April 2014 and is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office

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