About the louse itself

The scientific name of the head louse is Pediculus humanus capitis Ibarra J et al 1993.
Head lice belong together with the body lice and pubic lice to the sucking lice (order Anoplura).

This is how they look like:

Louse another louse

And to see them moving click HERE.

Head lice are elongated grey to grey-brownisch sometimes black in colour insects with six inwardly curved legs, each ending in a small strong single hook-like claw, and opposing "thumb" for hair grasping.
With this legs, they reach out and snatch a hair strand a couple of millimetres away. The claws open and the leg whips round to catch any nearby hair. The claws close like a pincer, and the louse holds on tightly. A louse can scurry from hair to hair with surprising speed, though it is unable to move effectively on a smooth surface. So, on a piece of tissue, a louse cannot move far. If it is hot and there is combing too, lice crawl around on the scalp with a top speed of 30 cm per minute. This is 0.5 cm per second.

The head is narrow. Lice have one pair of eyes. Eyes are present in all species within Pediculidae (the family which the head louse is a member of), but are reduced or absent in most other members of the Anoplura suborder. They have short antennae and the mouthparts are highly modified for piercing and blood-sucking, and retracted into the head when not in use. The body is flattened.

Adult lice can become up to 3 à 4 mm long. Males are a little bit smaller, nymphs (baby lice) are much smaller. On first sight they look somewhat like mouse shit. Eh … . Look HERE.
Head lice are not designed to fly or hop!!!!! So lice have no wings and no strong hind legs!!!

A fresh louse-egg (nit) is yellowish-white in colour, a bit transparent. Later on the an alive embryo containing nit, looks brownish to black, glances, is oval-shaped and about 0.8 mm in length. The hatched empty white eggshells (nits) remain on the hair but are not a source of reinfestation. Other bugs, dandruff, scabs, or dirt are often mistaken for nits or lice, which causes false alarm. The use of a magnifying glass could prevent misdiagnosis.

Nits

Nits

Life-cycle

Let´s start with day one on which an egg (nit) is laid and cemented at an angle to the side of a hair shaft.

The nit contains an embryo
The embryo changes into a nymph who crawls out of the nit (egg)
The nymph grows and after three mouldings the final molt gives rise to
An adult louse
After at least 12 but definitely after 24 hours the louse (well eh females) are capable of laying eggs

The eggs need at least 14 days to grow into adult lice. This depends on for instance temperature, moisture, food. In less favourable circumstances it takes up to 22 days.

A louse lays about 4-8 eggs a day. The nicest temperature to lay eggs is 32 °C. Beneath 10 °C and above 32°C it is no fun anymore Bos A F et al 2003. The eggs are attached near the base of the side of a hair shaft, generally within 1 cm of the scalp, with a very chemical-resistant waterproof glue. Preferable behind the ears and in the neck, because the embryo in the nit, just like lice, loves warmth, shelter and moisture.
Lice feed five to six times a day, by piercing the skin and sucking blood. Without food they survive for up to 55 hours.

Time table Life-cycle
After day.....	Egg	Nymph	Nymph grows	Adult louse	Egg laying louse	Louse dies
1	Egg
7,8		Nymph
9		Nymph	grows
10		Nymph	grows
11, 12			grows
13			grows	Adult
14-18			grows	Adult	Egg
19-22				Adult	Egg
23					Egg
24-30						†

Infestation

Head lice are common everywhere in the world, whether you are rich, poor, clean, smart, stupid, strong, weak, healthy, sick, black, white, yellow, pink, lice simply don´t bother.
The only thing they are interested in is, warm, moist, and dark (under the bangs, behind the ears, in the nape of the neck) and everywhere thin skin, well fed with blood is available and a bit rather scaly too, jummie.
Nevertheless it is striking that lice are more common than let´s say 40 year ago. Especially right after the summer holidays it′s party time!!!!
They say that girls with long hair hanging lose, are more often the fall guy and cutting hair should help. Unfortunately short hair facilitates lice in walking to another head. Of course those lice are more visible.
Head lice can only survive on human. Pets have the wrong blood and the wrong coat!!!! Bos A F et al 2003.

Head lice in Africa have different shaped claws compared to those living in for instance European countries. This has to do with the fact that frizzy hair has a oval-shaped cross section, and strait hair, a round cross section. So does an ‘European louse’ have a hard time in frizzy hair and an ‘African louse’ could forget it in strait hair Bos A F et al 2003.

Lice are mainly transmitted from person to person, and seldom by Orkin M et al 1985, Burgess IF 1995 Canyon DV 2002, Burkhart CN 2003 caps, hats, scarves, clothes, sheets… . Head-to-head contact is by far the most common route of lice transmission. Lice on clothes and on bedding are mostly weak sick old lice that could not hold on. A real louse would not be such a fool, to just leave a luxury food place.

If lice come into contact with water, for instance during bathing or swimming, they clamp themselves firmly onto the hair shaft and close the spiracles (openings to breath) from their with air filled trachea Downs AMR 1999.
It has been reported that they have the ability to close down their respiratory airways for up to 30 minutes when immersed in water. May be, in rare cases, a single louse can´t hold on anymore, releases the hair shaft, drifts on the water and just lands on another head. A swimming cap could probably be a reassuring idea.

How do you know whether you have lice

Itch

Could be a sign, but very often especially in the beginning there is no itching. Itching may occur if the individual becomes sensitized to antigenic components of louse saliva that is injected as the louse feeds. On the first infestation, sensitization may take four to six weeks Meinking TA, 1999. Some individuals can remain asymptomatic and never itch. Only 1 in 5 people is plagued by itch. It is even possible that after a few months the body gets used to all this, and the itch disappears mysteriously. The lice will definitely laugh up their sleeve.

In rare cases, the itch scratch cycle can lead to secondary infection with impetigo and pyoderma. Swelling of the local lymph nodes and fever are rare. Head lice are not known to transmit any pathogenic microorganisms. In extreme heavy cases there could be listlessness, paleness, light fever and anaemia too Orkin M et al 1985, Burgess IF 1995 Mumcuoglu KY 1991.

Visual inspection

Visual inspection underestimates the true prevalence of active infestation. In a normal healthy child, an infestation usually involves less than 10 live lice Meinking TA, 1999. Moreover, lice flee very quickly and disappear (they have special sensors to detect ‘rumbling’). Dark lice are also almost invisible in dark hair. Here is one running away: CLICK

(wet)Combing with a louse-comb

reveals the true prevalence of active infestation. About 3.5 times more lice are detected, compared to visual inspection Jahnke C et al 2009.

When wetting the hair, treating it with a hair detangler spray or other hair conditioner, not only facilitates combing but also facilitates finding lice and nits. The lice are unable to move, may be too by these ‘harmless’ so called ‘Inerts’ added to each conditioner Schettler 1996.

Then divide the hair into sections and fasten off the hair that is not being worked on.
Go thoroughly through hair sections from the scalp to the end of the hair. Nits are usually found close to the scalp. Sift through the same sections more than once.
Move on to the next section until the entire scalp and all hair has been checked.
When wiping the comb onto a white tissue after each stroke, louses are more easy to detect.
Dip the comb in a cup of hot, soapy water or use tape to remove lice, nits or debris from the comb.

If you stick a piece of gauze on the comb everything will be stuck on the gauze (the lice too) and this will prevent a lot of fuss.
An other nice hint is to heat up the comb for a short time (by dipping into hot water). Lice which usually are located on the scalp, will become more active and climb up onto the hair shaft (if they still can) Nuttal 1917, van Lith 1922.

Attention: Dandruff, scabs, or dirt are often mistaken for nits.

How to get rid of lice

Avoid spread of infestation

If one family member has lice, check all the family members. This means check and not automatic treat!
Warn the school, friends… . When you finally got rid of these lice you don´t want to be reinfested by for instance a less active friend.

To comb or not to comb that´s the question…

If turns out that you have lice, than you will have to comb EVERY DAY, FOR TWO WEEKS very carefully and systematically with a special nit-comb, (says including the British CHC Community Hygiene Concern), in the here already described way. If possible twice a day.
Children with curly/frizzy hair, will need 30 minutes instead of 20.

It is a common believe that combing is less needed when you use a official lice killing shampoo, cream rinse, lotion or spray. Unfortunately they all offer more than they usually can deliver. No remedy kills all nits and there will always be lice left that are resistant to these remedies. These of course start to produce more resistant offspring RIVM, Downs AMR, 1999, Kristensen M et al 2006, Durand R et al 2007, Maunder 1991.
So comb, comb and comb Garfinkel 1997. Combing with and without a insecticidal remedy (proofed) Lewendon G 1999, Bos A F et al 2003 has the same result. British scientists even claim that combing is more effective Hill 2005.

Even all enclosed instructions of Dutch malathion and permethrin containing anti-louse remedies say:

(quote:)
“de natte haren worden gekamd met luizenkam (… .) met een (gewone) crème spoeling erin. Dit is een onmisbaar onderdeel van de behandeling. Dit moet men dagelijks doen tot veertien dagen na de start van de behandeling. (…) minstens dertig slagen nodig, dat kost al gauw meer dan twintig minuten”
(einde quote).

Translation:
(quote:)
Wet hair is combed with a louse-comb(…) with an ordinary cream rinse in it. This is a obligatory part of the treatment. You will have to perform this up to fourteen days after the start of the treatment. (…) at least thirty strokes are necessary, which takes at least twenty minutes
(end quote)

But if intensive combing is an obligatory part of the treatment and with or without an anti head louse topical insecticide does not make a difference, than why bother using this expensive, unnecessary and potentially harmful pesticides… .
And how come, people still are seducible to use such in fact, inefficient dangerous methods… .

An often read hint but not proven, is to mix some vinegar into the water (1 cup vinegar and 4 cups water). This should dehydrate the nits and make them cling less firm to the hair shaft Attention! Never use vinegar right after applying an anti-louse remedy. (it makes the hair and skin less porous and lowers the efficiency).

And of course clean the comb after the job!!!!!

Topical insecticides

In the Netherlands the next topical insecticides are officially registered to treat head lice infestation. And are available at the pharmacist and chemist.

Prioderm® or Noury®:lotion, shampoo
Loxazol®: lotion
Para-Speciaal®: spray

Survey according the enclosed instructions
Trade name	Active ingredient	Min. soaking	Treat again	Instructions anno
Para-Speciaal® (Spray)	The pyrethroïds: bioallethrin and piperonylbutoxid	30 min.	After 8-9 days	14-3-2001
Loxazol®(Cream Rinse)	Permethrin	10 min.		2006 2 9
Noury®	Malathion	12 hours	After one week, if still nits and lice	2004 9 9
Priodermv (Shampoo)	Malathion	2x 5 min.	After one week, if still nits and lice	2005 12 9
Prioderm®(Lotion)	Malathion	12 hours	After one week, if still nits and lice	2006 1 19

Trade name	Auxiliary substances
Para-Speciaal® (Spray)	Butane, Petroleum oil
Loxazol®(Cream Rinse)	stearalkoniumchlorid, cetylalcohol, polyoxyethylene 10 cetylether, hydroxyethylcellulose, hydrolysed proteins, methylhydoxybenzoate, isopropanole 200 mg, Canada balsem, perfume, propylhydroxybenzoate, propyleenglycol, citrate, Sunset yellow (E110)
Noury®	ethanol
Prioderm® (Shampoo)	Cetostearyl alcohol, lauryldiethanolamid, etoxyled lanolin, methyl-hydroxybenzoate, propyl-hydroxybenzoate, sodiumlaurylsulfate, hydrochloric acid, disodiumfosfate, citrate, disodiummedetate (E110) and perfume
Prioderm® (Lotion)	Terpineole, perfume and isopropyl alcohol

Looking at the enclosed instructions may be something already begins to dawn on you. Studying scientific research definitely explains why anti louse remedies are, especially for children, very risky. And too why the National Pediculosis Association (NPA) warns so vigorously against them, and promotes combing wherever and whenever they can.

See for general information about topical insecticides: Topical insecticides

As obviously the public becomes more discriminating but is reluctant let go their former toys, the use of alternative remedies is booming business. What of course is very appealing to money makers. See: Alternative remedies

Success. Or not… .

If after 14 days you cannot find any lice or nits, than all eggs have hatched, no new ones are laid and all lice are dead. Quite often you will still see dead or empty nits. This is OK, they can do no harm.
Do you see alive lice or nits (alive nits are located less than 1 cm from the scalp) than you have no other choice as to start the whole anti-louse circus again.

Itch, without finding something, could indicate lice, but could also be mental.

If you still find lice than this may be one of the causes:

No combing every day
No systematic combing
Not the right comb
Not wetted the hair
Used no hair conditioner (you never know)
Stopped the treatment too soon
The anti lice remedy did not soak long enough
The anti lice remedy was too diluted (may be shampoo´s are less effective because of their dilution and short contact time Burgess IF 1995
VERY ANNOYING: some lice were resistant (very common)
THE MOST OUTRAGEOUS: In the meantime there was a re-infestation Vander Stichele RH 2001, Folia Pharmacotherapeutica 1998

Avoid is better than cure

Repellents

You´d expect that using repellents is a smart thing preventing head lice infestations, but the high toxicity of these repellents make them in fact useless Burgess IF 1995 Vander Stichele RH 2001, Folia Pharmacotherapeutica 1998, Canyon DV et al 2007. No one should be treated ‘just in case’. This leads to potential resistance of head lice to these chemicals. And shampoos containing insecticides can be toxic and so may cause real health problems. Preventive treatment does not make sense. Shampooing the hair with topical insecticides to avoid lice, is a waist of energy. The shampoo could irritate, cause itch and you could wrongly suspect a new lice invasion. From: http://www.gezondheid.be/index.cfm?fuseaction=art&art_id=370.

Plant repellents have hardly been examined. And the effect did not last long. Plants, whose essential oils do repel lice are citronella, cedar, verbena, geranium, lavender, pine, cajeputi, cinnamon, , rosemary, basil, thyme, garlic, peppermint, ginger, tea tree oil Quarles W 1996, Brown M., 1997, Barnard DR 1999, Duke J. 2002 Prajapati V et al 2005, Canyon DV et al 2007.

Tea tree and peppermint proved to be the best. Even better than DEET but still not good enough think Canyon DV et al (2007).
People used to protect their children against head lice infestations with lavender oil Mumcuogli et al 1996. Treating with citronella clearly does have a result but some children had complaints about this remedy Mumcuoglu KY et al 2004.

For fanatics: see the REPELLENT FACTSHEET about DEET (N,N-diethyltoluamide) in the JOURNAL OF PESTICIDE REFORM/ FALL 2005 • VOL. 25, NO. 3 (http://www.pesticide.org/DEET.pdf ) Attention: Combining DEET with permethrin, is ask for trouble. See: Permethrin.

So find another solution like:

Screening

The most important preventive action is inspecting all family members on a regular base, by visual inspection and by combing. Of course especially when head lice infestation is epidemic. And very important: Treat all infected family members at the same time. New infestations from objects (hats, caps, scarves, sheets, especially plush cuddle toys, stuffed animals…) are rare Donaldson 1979, Maunder 1983.
Combing for lice and nits isn't just about removing them. It's also about being able to screen and assure yourself that you are free of them. In fact screening (and so early detection for head lice) belongs to the other basic and affordable health measures like tooth brushing and hand washing. Early diagnosis makes treatment easier and reduces the possibility of infesting others.

Disinfect

Clean combs, grooming material and hair accessories, soak them eventually for 30 sec. in water of 60°C. Special disinfectant to kill the lice Speare Ret al 2000, 2003 is not necessary.

Who is still worried, could also soak other suspicious objects for 30 sec in water of at least 60°C, or wash at, at least 60°C, or feed the dryer (70°C) during 15 min, or steam, or hang outside for 48 hours, or hide for 24 hours in the freezer (-18°C), or forget during one week it´s in a plastic bag … .
Without food lice can survive one day at 37°C, two days at 25°C to 30°C, 7 days at 10°C to 20°C, and 10 days at 6°C!!! Bos A F et al 2003.
They figured this out for healthy lice, under lab conditions. Lice that dropped from the hair are almost all weak, old lice, with little change to survive Speare Ret al 2003. So there is no need to disinfect the car, the furniture, carpets… . One more time extra vacuuming should do it. An insecticidal treatment of the house and furniture is not necessary.
Fallen out hairs could have nits, that still could hatch after 6 days. But the change that just at this moment a head passes by is probably not big.

Lice capes, lice bags

There is a lot of advertisement about using lice capes/bags. A plain big plastic bag, which you can tie up and hang it with the handles on the coat rack, to put in the coat and cap, is fine too.

The comb

The right comb is obligatory for a successful treatment. In Vlaanderen the ideal louse comb is described as follows: The teeth

are spaced 0.2 - 0.3 mm
are angular-shaped, which means diamond-shaped or rectangular, to make lice stick between the teeth
are strong and a bit flexible

In the Netherlands next combs are available:

	The lice-comb is a plastic comb with on both sides short closely spaced teeth. With this one you can´t remove nits.
	The Nisska-comb is advised by the RIVM and is a steel comb with long more closely spaced teeth. With this one you can remove nits. The nits are striped from the hair or squashed van Lith 1922.
	The LiceMeister Comb. has long taper teeth that slides easy through the hair. Newton, Pray & Popovich 1999. This comb was developed by the National Pediculosis Association (NPA). This non-commercial American organisation promotes fighting lice without using chemical pesticides. She also informs about methods to control and get rid of lice and is doing research. Look at their very informative site: http://www.headlice.org .
	The electric louse comb should find and destroy lice by a light electrical shock. Despite the nice story, not everybody is as much delighted. If you understand Dutch read this: http://www.kidstoday.nl/wbs/projecten/News_CategoryView.aspx?id=%2Fwbs%2FProjecten%2F28%2F.

Bug Busting Programme

In the UK runs since 1995, a large scaled project: Bug Busting Programme against head lice. They have big publicity campaigns and give extensive information at schools. Above that, families get a Bug Busting kit with 4 different special combs, a 28 pages long manual and a waterproof cape. Also is there a Bug Buster video available. They claim their combs are the best. Including Denmark, Canada, Belgium participated in this project. The Deutschen Pediculosis Gesellschaft e.V. is very impressed by their approach. It proves that this approach (including combing in the right way) definitely pays off Dawes M et al 2006, Ibarra J et al 2007.
The project is executed by the Community Hygiene Concern (http://www.chc.org), which is supported by the Department of Health. See for a demonstration HERE.

School and day-care head lice and nit policies

Quote:
“Although lice and their eggs may be seen without the help of magnifying devices, the viability of the eggs cannot be judged without magnification and a degree of training.
Of more than six hundred samples of presumed lice and nits submitted to us for examination, fewer than two-thirds contained evidence of any infestation. The remainder of the samples were composed of miscellaneous insects or of artifacts that resembled eggs. Of those samples that did contain bona-fide louse eggs, many were comprised solely of hatched or dead eggs; thus, no treatment would be warranted.

We noted that:

health care professionals as well as non-specialists frequently over-diagnose this infestation
non-infested children are quarantined as often as infested children
traditional pediculicides and ‘alternative’ formulations are frequently over-applied…

(Pollack RJ, Kiszewski A, Spielman A. Overdiagnosis and consequent mismanagement of head louse infestations in North America. Pediatric Infectious Disease Journal. 2000; 19:689-693)

In Holland each school has its own policy. Schools decide themselves how to treat lice. Sometimes there are lice brigades, lice coordinators, lice inspectors, lice parents, lice groups. But not all parents agree their children to be screened at school.

Sometimes there is a official/modest rule: Child diagnosed with lice or nits, will have to be picked up immediately. In the meantime the child is separated from its classmates. Sometimes children are for several days excluded from school. There are childcare settings where children are dismissed immediately, when they have lice or nits. These forms of quarantine can be very upsetting and extremely harsh for these children and it is questionable whether this is sensible from a pedagogic point of view.

Other schools inform the caretakers of the invested child by a letter and tell how to deal with the lice.

Fortunately there are schools too, where the most appropriate anti lice measurements together with the parents, caretakers and kids are considered. This open, multidisciplinary approach of shared responsibility is preventing that children who have a hard time, will get an unnecessary still tougher time. It also prevents that children who never have been bullied suddenly don´t fit into the group anymore. This approach is preventing too that children who are more susceptible to lice, become victim, in more than one way.

Myths

Quite a lot, sometimes very persistent, dispelling, myths about lice themselves and how to get rid of them are circulating.
See: MYTHS.

References

See: Literature.
See: Internet sources.