Pediculosis are parasitic lice infections in humans, extremely widespread and known for thousands of years. Lice are hematophagous insects (which feed on blood), of which only three species out of the more than 4000 recorded, are parasites of man.

Pediculosis means infestation with lice in humans. There are three pediculosis: scalp pediculosis which mainly affects children, bodily pediculosis, a sign of poor health and vector of infectious diseases, and finally pubic pediculosis or “lice”.

The causes of pediculosis

The three exclusive lice of man are called pediculus humanus, we can distinguish:

• pediculus humanus variety capitis, responsible for hair lice or head lice. This scalp attack has experienced an upsurge in recent years.
• pediculus humanus variety corporis giving body lice, which were very common during World War I and are now seen rather in a precarious situation (SDF, migrants…).
• phtirus pubis, responsible for pubic phthiriasis, colonization by “crabs” of pubic hair, which must most often be considered a sexually transmitted disease.

Who is most often affected?

Pediculosis of the scalp mainly affects children when they frequent communities (schools, nurseries, holiday centers, etc.).

Body lice are mainly found in people living in precarious conditions (lice are found in clothes that are rarely washed).

Pubic phthiriasis is mostly seen in people with multiple sexual partners.

Evolution et complications possible

Pediculosis has a tendency to become superinfected due to scratching.

In bodily pediculosis, the body louse can inoculate bacteria (Bartonella quintana causing trench fever, Rickettsia prowazeckii causing exanthemous typhus, and Borrelia recurrentis causing relapsing fever).

In the event of pubic phtiriasis, the often sexual contamination should lead to the search for other sexually transmitted diseases (HIV, herpes, syphilis, chlamydia, etc.).

All pediculosis has itching in common. The site varies depending on the louse involved:

Pediculosis of the scalp causes itching of the scalp and pimples usually located in the back of the neck (the hottest place, where lice sting to suck blood)

Body lice cause itching predominantly in the folds (axillary, inguinal, etc.) and itchy pimples

Pubic phthiriasis causes itching of the pubis, or even pimples.

Risk factors

Pediculosis of the scalp is common in children in communities (schools, nurseries, holiday centers, etc.). The risk factors are long hair that is not tied up, the exchange of hats, caps, scarves, close contact and games between children.

Body lice are found in seldom washed clothes. They are therefore frequent in the event of insecurity, the purchase of second-hand clothes and unwashed clothes.

Pubic phthiriasis is seen mostly in people who have multiple sexual partners, with or without a condom. Hair removal of the pubis is a protective factor against phthiriasis (while it promotes other sexually transmitted diseases such as herpes, molluscum contagiosum, etc.) because the pubic louse needs hair to move and lay eggs.

Our doctor’s opinion

The most commonly encountered pediculosis is that of the scalp. Parents are often confused by recurrences in their children. Here are the causes of treatment failure that should be addressed:

• Lack of treatment for small community comrades (class, nursery, etc.) who are therefore still contaminants and again spread the disease in the community. Sometimes the cause is the cost of treatment.
• Poorly done treatment: no disinfection of textiles, product application time too short, quantity of product applied too small, product imperfectly lenticidal or showing resistance, absence of new treatment 8 days after the first.

It is therefore often necessary to go through the course of the treatment point by point to see what was missing and not to hesitate to change the product because there is often resistance.

Prevention

Pediculosis of the scalp is in part prevented by avoiding the exchange of hats, caps, scarves, helmets, etc. and wearing short or tied hair if they are long: lice do not jump but go from hair to hair during close contact, the longer your hair is, the more likely you are to be contaminated.

Part of the prevention of pediculosis of the body is by washing second-hand clothes before trying them on.

Pubic phthiriasis is partly prevented by full hair removal from the genitals and the pubis (“crabs” cannot cling from one person to another if there is no hair).

Anti-lice treatments

The treatments used must have a pediculicidal and lenticidal activity. They are not reimbursed by Social Security.

Scalp pediculosis

The product can be an insecticide in lotion (malathion, Prioderm * to be avoided before two years, pyrethrins: Para *, Spray Pax * …), often more effective than shampoos, or an asphyxiant product (dimeticone, such as Pouxit * or Apaisyl *).

The lotion should be applied line by line, in sufficient quantity to wet the entire scalp. It stays in place between a few minutes and a few hours depending on the lotion used. It is necessary to follow the instructions for use provided, then the product is most often rinsed with a non-treating shampoo.

The hair is then combed for sharpening.

Combs, brushes, hats, hats, scarves, fluff, bedding must also be decontaminated with a contact insecticide or by simply washing them at 60 ° C in a machine.

Body pediculosis

For pediculosis of the body, disinfection of underwear and bedding is generally sufficient by washing at 60 ° C. Textiles not washable at 60 ° C must be insulated in a plastic bag for at least 3 days. The patient should take a shower with soap to remove any lice present on the skin and hair. Shaving of the hairs is necessary in the event of abundant nits.

Phtiriase

Treat sexual partners and look for a concomitant STI

On the eyelashes, it is possible to apply a cream based on permethrin at 1% or, failing that, pure petroleum jelly.

Pediculosis of the pubis is treated with the same products as that of the scalp, with an insecticide in lotion (malathion, Prioderm * to be avoided before two years, pyrethrins: Para *, Spray Pax *…). It is preferable to treat all the hairy areas of the trunk and thighs, but not the scalp. Shaving the hairs is sometimes necessary in the event of abundant nits and it is necessary to deworm clippers, razors, scissors… by soaking them in water at over 65 ° C for at least 10 minutes. The clothes which have been in contact with the infested area of ​​the person during the 3 days preceding the treatment are disinfected by washing at 60 ° C. Textiles not washable at 60 ° C must be insulated in a plastic bag for at least 3 days

Complementary approaches

Proven: pyrethrins

Pyrethrins are a set of substances with insecticidal properties, derived from the flowers of Dalmatian pyrethrum or certain chrysanthemums, in particular the Persian chrysanthemum (Tanacetum coccineum). They are marketed in pharmacies under the trade names Para *, Spray Pax * …

To prove: coconut oil

Coconut oil would have an asphyxiant effect but only dimeticone has been the subject of scientific studies proving its asphyxiant effect in the management of pediculosis.