Pubic and Body Lice
Pubic and Body Lice
- 1 Pubic and Body Lice
- 2 Trending Articles
- 3 Pubic lice 
- 4 Body lice
- 5 The Life Cycle Of Head Lice
- 6 Frequently Asked Questions – Head Lice Life Cycle
- 7 2 Comments
- 8 Pediculosis: incubation period of lice and nits
Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Pubic and Body Lice article more useful, or one of our other health articles.
Pubic and Body Lice
In this article
Lice are blood-sucking insects and specific parasites of human beings. Lice are 1-3 mm long and have three pairs of legs that end in powerful claws.
Coronavirus: how quickly do COVID-19 symptoms develop and how long do they last?
Coronavirus: what are asymptomatic and mild COVID-19?
Coronavirus: what are moderate, severe and critical COVID-19?
COVID-19: can I get tested for coronavirus?
COVID-19: how to treat coronavirus at home
Is losing your sense of taste and smell a symptom of coronavirus?
Quiz: Am I pregnant?
Quiz: Am I depressed?
What your swollen glands could mean
COVID-19: how to look after your mental health during coronavirus lockdown
COVID-19 coronavirus: what to do if you need to see a GP or get medication
COVID-19: What is a risk group?
COVID-19 coronavirus: do you need to disinfect your home?
What causes vaginal odour after sex?
COVID-19 coronavirus: what is an underlying health condition?
What your vaginal odour could mean
Gallstones diet sheet
Why you constantly need to pee
COVID-19 coronavirus: what is shielding and who needs it?
Quiz: When will I get my first period?
COVID-19 coronavirus: what can I do under the new rules?
COVID-19: is handwashing still important when you’re self-isolating?
When it feels like something is stuck in your throat
COVID-19 coronavirus: what to do if you’re too ill to care for your children
When to worry about night sweats
COVID-19: how to look after your sexual health during coronavirus lockdown
The best way to treat a herpes outbreak
When to worry about a persistent cough
What your constant yawning could mean
COVID-19: what to do if you feel suicidal during the coronavirus lockdown
- Pubic lice are slightly smaller than head lice and body lice.
- The female lives for 1-3 months but dies when separated from the host. The female louse lays up to 300 eggs, called nits, during her lifetime.
- The nits are less than 1 mm in diameter and, when viable, are opalescent. The nits hatch 6-10 days after they have been laid, giving rise to nymphs that become adults in 10 days.
Three species of lice have adapted to live on humans:
- Head louse (Pediculus humanus capitis) — see separate Head Lice article.
- Crab (or pubic) louse (Pthirus pubis).
- Body louse (Pediculus humanus).
Pubic lice 
The pubic louse (Pthirus pubis) is ‘crab’-shaped, grey-brown in colour,and about 2 mm in length. The female lays eggs (smaller than a pinhead) on the hair shaft, near to the body. The eggs hatch after about 6-10 days. The empty nit eggshells are tightly attached to the hair. The female louse lives for 1-3 months. Eradication of pubic lice from the body is unlikely unless treated.
- They are common among young adults.
- Pubic lice infest 2% to over 10% of human populations  .
- Pubic lice are transmitted by close body contact, which can be from sexual contact or from close family contact (eg, from an infested beard or chest).
- Pubic lice in children may be an indication of sexual abuse but most children with pubic lice infestation have probably acquired this innocently.
- The incubation period is usually between five days and several weeks  .
- The diagnosis is based on finding adult lice or eggs. Pubic lice live on coarse hair, especially in the pubic and perianal areas but also on the eyelashes, abdomen, back, axillae and the head. Therefore, all hairy parts of the body should be examined. A fine-toothed comb may be useful for detection  . Dermatoscopy has also proved a useful diagnostic technique in cases of doubt  .
- Itchy red papules are the most common presentation. Itching takes 1-3 weeks to develop after the first infestation but may occur immediately following re-infestation. Itching tends to be worse at night.
- Blue macules may be visible at feeding sites  .
- Minute dark-brown specks of louse excreta are sometimes seen on the skin and underwear.
Differential diagnosis 
- Nits: seborrhoeic scales, small crusts of scratched dermatitis, hair muffs (secretions from the hair follicle that are wrapped round the hair shaft). These can all be brushed off but nits are firmly attached to the hair.
- Body (clothing) lice (Pediculus humanus), which are slightly larger than pubic lice and found only on clothes; head lice (Pediculus humanus capitis — slightly larger than pubic lice and found only on the scalp).
- Itchy red papules: scabies.
- Consider whether the pubic lice infestation has been acquired via sexual or non-sexual contact.
- If acquired via sexual contact, refer to a genitourinary medicine (GUM) clinic for treatment, screening for other sexually transmitted infections and contact tracing  .
- Treat the individual with a topical insecticide: two applications of malathion 0.5% aqueous lotion or permethrin 5% dermal cream, seven days apart. All surfaces of the body should be treated, including the scalp, neck and face (paying particular attention to the eyebrows and other facial hair)  .
- Advise the individual to avoid close body contact until they and any current sexual partner have been treated.
- Any close contacts over the previous three months should be examined for pubic lice.
- For people with infestation of the eyelashes, treat the eyelashes with an inert occlusive ophthalmic ointment (eg, simple eye ointment BP) or a topical insecticide (a cream rinse or shampoo should be used). An inert occlusive ophthalmic ointment should be used for people under the age of 18 years and for those who are pregnant or breast-feeding  .
- If pubic lice infestation is unresponsive to initial insecticide treatment, repeat the previous treatment with the correct technique (rather than switching to a different treatment).
- If insecticide resistance is suspected, switch to the alternative insecticide (malathion or permethrin).
- When re-infestation occurs, repeat the previous treatment; assess all close contacts for pubic lice and treat all positive cases simultaneously.
- Excoriation and skin infection due to scratching.
- Blepharitis, conjunctivitis, or corneal epithelial keratitis when the eyelashes are affected.
Shaving the infested areas does not provide protection from re-infestation because pubic lice need only a minimal length of hair on which to lay eggs. One study suggests the recent trend towards removal of pubic hair has reduced the incidence of pubic lice in the general population  .
- Pediculosis is usually caused by contact with an infested person.
- The body louse (Pediculus humanus) is most often seen in cold climates, in poor sanitation and with overcrowding  .
- Body lice also occur mainly when clothes are not changed or washed regularly. Therefore, homeless populations are predominantly affected  .
- Pediculosis and scabies may co-exist in the same individual.
- Patients usually present after discovering lice or nits.
- Many lice infestations are asymptomatic.
- Pruritus is accompanied by excoriations that can become infected secondarily and papules linked to bite reactions.
- Diagnosis is based on seeing eggs (nits), nymphs or mature lice. Observing lice is difficult. Nymphs and mature lice, despite being unable to hop or jump, can move rapidly through dry hair. The use of a magnifying glass assists with diagnosis.
- Mature lice are 3-4 mm long. Nits are much smaller (about 1 mm). The pubic louse is about the same length as the head or body louse but has a wider body.
- Body lice can be found in any area of the body, although they tend to avoid the scalp, except at the margins. Nits are laid in the host’s clothing and are not usually found on the hair as with head lice and pubic lice. Body lice and eggs are found in clothing seams  .
- Unlike dandruff and hair root sheath casts, nits are stuck to the hair and are difficult to remove.
- Nits are fluorescent under a Wood’s light.
Treatment includes improved hygiene and laundering in hot water of all the infested clothing, bedding and linens. Drug treatment (eg, malathion or permethrin) is required in large-scale infestations  .
- Bed linens and clothes must be systematically decontaminated.
- Hygiene and washing clothes, bedding and towels are most important and are usually sufficient but application of permethrin or malathion may be required.
- Outbreaks require delousing of people with 1% permethrin dusting powder, basic sanitation and hygiene, changes of clean clothing, and sometimes shaving.
- Antibiotics are needed to treat louse-borne infectious diseases.
- Treating clothing with permethrin may prevent infestation.
The body louse acts as a vector for trench fever, epidemic typhus and relapsing fever  .
The Life Cycle Of Head Lice
There are 3 different stages in the life of head lice:
– head lice eggs, also called nits
– adult head lice
The life cycle of head lice means the period of time between the moment head lice eggs are laid by the female until the moment head lice die. The head lice life cycle lasts about 45 days.
Head lice reproduce very quickly. The male is a tireless lover who can fertilize 18 females in a row without having a rest. The females mate several times during their adult life, which can vary from ten to forty days, usually about 20 days. They lay up to 10 lice eggs or nits daily.
1. From Egg To Nymph: One Week
Head lice incubation period lasts about a week (from 6 to 9 days exactly), which means that head lice eggs or nits hatch occurs about a week after eggs have been laid. Head lice eggs hatch to release a nymph. The latter resembles the adult lice, but of course it is smaller, and it measures about 1 millimeter, the size of a pinhead
2. From Nymph To Adult Louse: Another Week
The adult stage is reached after approximately 7 days after three successive molts. Thus, from the laying of the egg to the emergence of adults are 17 days, and the adult will live for about 30-40 days.
3. Adult Stage: One Month
The lifespan of head lice when adults is about 30 days. This means that head lice, once they have reached the adult stage, will live for about one month. Actually, they can only live about this period of time on a human host, as they need to feed on blood several times every day. Away from a human scalp, they will die within 48 hours.
Eggs: Nits are laid by the adult female and are cemented at the base of the hair shaft nearest the scalp.
Nymphs: The egg hatches to release a nymph.
Nymphs mature after three molts , .
Adults: The adult louse is tan to grayish-white . In persons with dark hair, the adult louse will appear darker. Females are usually larger than males.
Frequently Asked Questions – Head Lice Life Cycle
- How long do head lice live?
On a human head, head lice live up to 30 days.
- How long does head lice live without a host?
Away from someone’s head (on furniture, carpets, clothing, bedding, etc) head lice can live up to 2 days. This is true for nymphs and adult lice. However, nits can live up to 9 days away from a host (until they hatch).
- How long can head lice live in clothing?
Head lice can live up to 48 hours in clothing. After this time, they die because they cannot feed on human blood. As far as nits are concerned, they can live up to 9 days on a hair away from a head.
I read you can tell how long the infestation is by how far down the hair shaft the nit is. We found 9 lice and 16 nits on my daughter and have not found anymore since. Some nits were right at her head and most maybe an inch away from her head. We did not find any hatched nits as we found the lice cleaning out flour from her hair from halloween so it was hard to tell what was what and it took a couple days to wash out the flour!
I found the lice on my daughter because I noticed her scratching her head a lot. When I saw the louse on some hairs, I pinched it between my fingers and slid it down the hair shaft to get it off. At first it looked like a wing from a gnat or something, it was so small! I went out immediately and bought lice shampoo. I only “saw” 3 lice ; the one I described previously, one while putting on the lice shampo, and one while combing through her hair with the nit comb. I found a few hundred nits…I didn’t count, but there weren’t so many that I couldn’t have. It was a long and uncomfortable process, and I’m very glad we did it. I checked her head again the next day and found some nits I missed. I’m going to keep checking daily, and I’ll reapply the shampoo on what will be the 9th day after the first application. I’ve vacuumed my furniture and car as well. Washed and dried all the bedding in HOT. Most importantly … I told everyone of our friends who she may have had head to head contact or who came for a sleepover before we discovered the lice.
Pediculosis: incubation period of lice and nits
Pediculi are ectoparasites, meaning they live on top of their hosts instead of inside of them. They are small, six-legged insects with claws adapted to clinging onto their host’s hairs or clothes. Pediculi mouth-parts are adapted to sucking the host’s blood, and in the case of capitis, they are also adapted to eating dermal parts of the host’s scalp, neck and eyelids. See the picture in general information, above.
The History of Pediculosis
Pediculosis as a human problem dates back to the earliest Homo sapiens. Researchers at the Max Plank Institute for Evolutionary Anthropology used Molecular Clock Analysis (MtDNA) to date the origins of human lice to approximately 72, 000 years ago in Africa. Expansion of lice into other parts of the world follow the expansion of modern man out of Africa approximately 50, 000 years ago.
«Out of Africa» — The orange arrows outline the likely route of modern human beings out of Africa
50,000 years ago.The spread of Pediculosis humanus is believed to have followed this same route.
- Combing or shaving hair (Ancient Egyptians)
- Drinking garlic concoctions (Greece)
- Greek naturalist Pliny the Elder (23-79 CE) recommended destroying nits using dog’s fat or eating cooked serpents.
Clinical Presentation in Humans
Typically asymptomatic. Symptoms that may appear are itchiness of the neck, scalp and ears, pruritis, as well as puss in affected areas (bites). In more severe cases secondary bacterial infections can develop which may lead to febrile episodes as well as enlargement of the cervical and nucal lymph nodes.
Itchiness and visible bite marks on the body and pruritis, especially around the waist and armpits. There may also be crusting and redness due to secondary bacterial infections.
Itchiness in pubic areas and armpits is the most common complaint although not always a complaint. Pale blue spots at the follicular orfices may appear in the case of a prolonged infestation.
Transmission, Reservoir and Vector Information
- Human to human transmission is the only way pediculosis is transmitted. Transmission and infection are usually the results of low levels of personal hygiene
- Tranmission of head and body lice is common where crowds of people are in close contact, such as in schools, prisons and trenches.
- Contact with infected hair (i.e. sharing combs and/or hair brushes) can transfer head lice between individuals
- Contact with clothing and bedding facilitates the transfer of head, body and pubic lice between human hosts
- Sexual contact facilitates the transmission of pubic lice between individuals
Life Cycle and Incubation
Diagnostic Test s
Identification of louse and nits. This can be aided with the use of a fluorescent Underwood light. Careful and thorough combing can also be done to search for nits and lice. Official measure of diagnosis is the presence of nits within 6.5 mm of scalp.
Identification of louse or nits on clothing. The adult louse may hard to identify because they move quickly across the body and clothes.
Identification of louse or nits in the pubic and armpit areas. Identification of the adult may be difficult because of its translucense.
Management and Therapy
|The best preventative measure against all types of lice is to practice constistent and adequate measures of personal hygiene. This includes washing head and body hair in warm water (temperatures of greater than 130 degrees Farenheit may kill adult lice), as well as laudering clothing on a regular basis.
Other means of preventing the spread of pediculosis include not sharing personal hygeine items such as hair brushes and combs, as well as towels and unwashed clothing. One recommendation as a preventative measures for elementary-school aged children is to provide them with individual hooks for caps and coats to prevent the spread of head lice.
What to do when you do have lice:
The best primary treatment for headlice is a topical insecticide although drug resistance and persistent infections may require oral medications.
Over-the-counter lotions such as 1% Permethrin cream rinse (brand name Nix) and Pyrethin (brand names Rid, A-200, Pronto and Clear) are toxic to lice yet have low toxicity and low rates of allergic reaction in mammals. Pyrethrin containing lotions are the recommended first-line treatment against head lice. Insecticide lotion available by prescription within the U.S. is 5% Malathion (Ovide).
Method of administration: Wash hair and towel dry. Cover the scalp with the lotion and let sit for ten minutes, then rinse with water. The CDC recommends repeating the treatment 7-10 days after first treatment. Malathion treatments require that the lotion sit for an 8-10 hour period before rinsing hair.
Lindane shampoo is effective but toxic, so its use is discouraged.
Ivermectin may be prescribed for a persistent and a resistant infection. A single 200 ug/kg dose should be administered, and repeated once, 2 weeks later.
Recommended for children under age two
Have infected individual bathe thoroughly. Be sure to wash clothes and bedding in warm water and dry in heat. Body lice can survive off of the body for 30 days so it is important to prevent re-infection by washing items that may have come in contact with infected person and his/her clothing.
Lindane lotion may be recommened (washed off after 8 hours) . Corticosteroid creams can be used for pruritic and irritated areas, applied twice daily
Remove nits with finger nails, a comb and/or tweezers. Be sure to check for recurrent infection, treat contacts such as sex partners and wash bedding and clothing in warm water.
Permethrin, Lindane and Pyrethrin lotions may be used for treatment (see directions above). Be sure to dry and cool skin before applying lotions.
Iveremectin may be used as a second-line medication if resistance occurs. Typically use in conjunction with 5% permethrin cream. Leave cream on for 8 — 12 hours or give two doses of ivermectin (200 mcg/kg) one week apart.
Do not use ivermectin in children less than 15 kg or in pregnant or breast-feeding women.
About 1/3 of people with pubic lice will have a second venereal disease and they should be screened.
Epidemiology and Public Health Strategies
Lice are found in countries all over the world, not excluding the most developed societies of Western Europe and the North America. Individuals from all socio-economic backgrounds can be affected by lice, although this is more true for head lice than body lice, which typically affect homeless individuals to a greater extent than individuals who have access to washing machines and hot baths. Head lice have infected elementary-aged school children in North America at epidemic proportions, and head lice infect more children than all other communicable diseases combined (6-12 million children infected each year).
Public Health Strategies
CDC recommendations for head lice outbreaks in schools:
Other public health strategies for all types of lice include encouraging proper hygiene practices. Regular laundering of clothing and bedding in hot water for at least 20 minutes can kill lice. Additionally, increasing peoples accessibility to hot water can help slow the spread of Pediculosis.
Useful Web Links
The National Pediculosis Association Inc. website: http://www.headlice.org
UpToDate websource for medical journals and health information: http://www.uptodate.com
GIDEON: Global Infectious Disease and Epidemiology Network: http://www.gideononline.net
Centers for Disease Control — Division of Parasitic Diseases. «Pediculosis.» Accessed on 26 May 2005. http://www.cdc.gov/ncidod/dpd/parasites/lice
Cohen, Bernard. «Pediculosis capitis.» Dermatology Image Atlas. Accessed on 1 June 2005.http://dermatlas.med.jhmi.edu/derm/IndexDisplay.cfm?ImageID=259663642
GIDEON — Epidemiology information, images: «Pediculosis.» 2005. Accessed on 26 May 2005. http://www.gideononline.net
Goldstein, Adam O., Goldstein Beth G. «Pediculosis». UpToDate 13.1. February 24, 2005. Accessed on 26 May 2005. www.uptodate.com
Ha, Chris. «Pediculosis Corporis.» Dermatology Image Atlas. Accessed on 1 June 2005. http://dermatlas.med.jhmi.edu/derm/IndexDisplay.cfm?ImageID=1017889414
Kitter R, Kayser M, Stoneking M. «Molecular evolution of Pediculus humanus and the origin of clothing.» Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany. Curr Biol. 2004 Dec 29;14(24):2309.
Markel, John, Krotoski. Markell and Voge’s Medical Parasitology. 8th ed. Elsevier Science Health Science div, 1998.
Mumcuoglu KY, Zias J, Tarshis M, Lavi M, Stiebel GD. «Body louse remains found in textiles excavated at Masada, Israel.» Department of Parasitology, The S. F. Kuvin Center for the Study of Infectious and Tropical Diseases, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
The National Pediculosis Association. Accessed 22 May 2005. www. Headlice.org.
Shahdi, Majid. «Phthrius pubis.» Dermatology Image Atlas. Accessed on 1 June 2005. http://dermatlas.med.jhmi.edu/derm/IndexDisplay.cfm?ImageID=-1993095391
Smith, Scott. D. «Pediculosis» Lecture, Stanford University. 18 May 2005.
Author: Stacy Zambrano, student at Stanford University