Ectoparasitoses

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I- Definition :

Les ectoparasitoses, scabies and pediculosis, are communicable diseases interpersonal.

II- Gale :

GALE, parasitic skin disease, is due to a mite, Sarcoptes scabiei Man, mandatory human parasite.

Photo : female mite (Sarcoptic mange scabieu agent), mandatory human parasite. (M.P. B renier Pinchart)

A- Pathogen :

The female mite (0,4 mm de long) is responsible for this disease. It burrows into the stratum corneum of the skin and deposits eggs in the bottom of it (Lien 1). The adult lives 4 at 6 weeks, but only 24 at 36 hours outside of its host. On the other hand, eggs are in a dozen days in the environment.

B- Epidemiology :

Scabies is transmitted primarily by direct human contact, it is also sexually transmitted. Scabiei mite parasite millions of people worldwide on all continents, of all social levels and all ages. Scabies occurs by cyclic epidemics, especially in elderly homes. Since 1999, this infection is on the list of occupational diseases contracted in the middle of hospitalization.

Photo : skin : scabiose ( gale) Typical lesions intergdigitales (Anofel)

C- Clinique : common scab adult

The incubation period is 2 at 3 weeks, and intense pruritus, widespread and night upsurge appears, it is the major sign of scab. Specific lesions of scabies – scabious burrows and vesicles beaded- must be sought in the interdigital spaces of the hands, the front face of the wrists, elbow, the anterior face of axillae, the umbilical region, buttocks, the inner thighs and nipples in women.

Photo : scabiose (gale) penile chancre (Anofel)

nodules, the scabious nodules, can be observed at the rod and the front face of the axillae. These lesions can be missed and replaced by secondary lesions, scraping ridges, papules excoriées, eczematisation and superinfection (impetigo). The face, scalp, neck and upper back are rarely achieved in common form.

D- Other clinical forms and complications :

Photo : scabiose ( gale) Reaching the foot in & rsquo; child (Senegal) (Anofel)

Semiotics can vary depending on terrain.

In infants, location type vesicular-bullous lesions can be palmoplantar, and spread to the whole body.

In the elderly, the lesions are often atypical. papular eruption is observed, vesicular, disseminated on the trunk, members and back, without furrow.

In immunocompromised patients (corticosteroids, HIV, HTLV…), a heavy infestation, highly contagious can be observed, it is the crusted scabies or Norwegian scabies. Erythematous papules are scattered all over the body, scabs and hyperkeratotic ("Mealy"). One can find lesions on the scalp and face.

E- The diagnosis :

The diagnosis is sometimes difficult. The detection of the parasite in the dander remains the reference. It requires the completion of scraping with a curette or lancet on more sites for the collection of serum and dander. Microscopic examination between blade slide for the presence of adult mites, larvae, eggs or droppings. The negativity of this review does not formally exclude the diagnosis. However, performing a systematic test treatment, by a topical ascaricide, is also a source of error. Scabies must be among the differential diagnosis of any persistent or unusual pruritic condition.

F- Treatment :

The treatment concerns the patient himself, her entourage, his clothes and bedding.
Treatment is to scabicides topically or more recently an oral drug.

Active ingredient Specialty Form
galenic
Dosage / method of administration Effects
secondary
Benzoate de benzyle Ascabiol lotion 10% A : the evening , during 24 h, avoid scalp, face
E < 2 years : 12 h max : prudence (dilute x 2 the product)
irritation

eczematisation

Synthetic pyrethroids Sprégal Aerosol A and : body except face and scalp, 12 h (night) irritation

Asthma (aerosol)

organochlorine,
lindane
Scabécide cream 1% A: 12 h
E > 2 years : 6 h
YOU : < 2 years, pregnancy
Eczema risk of toxicity
neurological, haematological and hepatic

After treatment with one of these scabicides, itching may persist for ten days, this postscabieux pruritus should not lead to repeated applications. These products are not reimbursed by Social Security. These drugs should not be applied to mucous membranes and be used with caution in children. The use of products containing lindane is questioned because of their toxicity.

ivermectin Stromectol tablets 200g / kg enprise single IC or precautions < 15 kg , pregnancy Exacerbation of pruritus at the start of treatment

Healing will be estimated as final as 4 weeks after treatment. This drug has a special place in the event of community outbreak due to its ease of use. In case of crusted scabies, dermatology is essential hospitalization.

It is necessary in association with the treatment to disinfect linens and bedding contaminated by washing more than 60 ° C or if the- is not washable by a spray insecticide or powdered (higher toxicity)(Aphtiria®).

The contact persons should be treated simultaneously.

III- pediculosis :

Lice are bloodsucking insects, parasite strict man. There are three species of lice owned 2 genres : Human head and body lice, and Phtirus pubis. The transmission is direct person-and in the vast majority of cases. These measure of ectoparasites 1 at 4 mm, dorsoventrally are flattened and provided with 3 pairs of legs ending in claws. The female lays eggs : slow.

Characteristics Pediculus humanus capitis (lien 5) The human body louse Phtirus pubis (lien 6)
Dimensions (L) The most common 3,5 mm Utmost 4,5 mm thickset 1-2 mm
Location Scalp, hair Clothing Pubic hair or eyelashes
Characteristics Frequency, child, benign Poverty, disease vector MST
Photo : Pthirus pubis adult (MEBx33) (Anofel)
Photo : outbreak & rsquo; slow (Anofel)

A- Head lice :

Photo : head lice (Anofel)

Pediculosis of the scalp is the most common pediculosis. It exists primarily among children in schools, all social backgrounds and adults with poor hygiene. Transmission is usually through direct contact ; flanking (bonnet, hat, comb…) is much rarer.

Yeah manifest by a pruritus located au début in the occipital region. Then, the prédomine dans les régions et temporales occipitales et peut être à l'origine de grattage lesions of inflation if surinfecter. The slate stains are sometimes observed. Slow living is dark (lien 4) and close to the scalp and difficult to see lice (mobile and small : 10 /head).

B- Body louse :

Body lice mainly affects individuals in precarious situations (SDF). Lice, Pediculus humanus corporis are found in clothing, they come to feed on the body. The bites can cause local allergic reactions and are responsible for pruritus. This is accompanied by an eruption roughly Urticarial, with lesions from scratching and eczematisation. The lesions predominate in areas covered (armholes, scapular and lumbar region). In chronic infestation, there is often a leucomélanodermie "vagrants".

Body lice are potential vectors of serious diseases : trench fever (Bartonella Quintana), the typhus typhus (Rickettsia prowasekii) and cosmopolitan relapsing fever (Borrelia recurrentis).

C- Phtiriase :

Photo : pthirus pubis (morpion) adult (Anofel)

Phtirius pubis or inguinalis is usually attached to pubic hair, but can affect other hair whose eyelashes (blepharitis phtiriasique infant or child- physical examination in search of sexual abuse is essential). These bites cause small bluish lesions and sometimes quite significant allergic reactions. The transmission of pubic lice is especially sexual (MST), non-sexual transmission is rare. Screening for other STIs can be proposed.

D- Treatment of pediculosis :

Several insecticides are used in anti-lice preparation : pyrethrins, natural or synthetic, organophosphorus (malathion), organochlorine (lindane). Dosage forms and business presentations are numerous, as these are hardly considered drugs, therefore not marketing authorization and are not reimbursed by social security. They must have a pediculicide and lenticide activity. The lotion is the most appropriate pharmaceutical form (prevent flow to the mucous membranes).

Example products, we seemed particularly interesting (not exhaustive) :

Active ingredient Specialty galenic Efficiency Side effects
Pyrethrins synthetic d-phenothrin 0.3% Item Lotion pediculicide,
Lenticide
neurological irritation (low)
Organophosphoré
Malathion
Prioderm Lotion pediculicide,
Lenticide
Irritation, pulmonary, digestive, neurological
Synthetic pyrethrin + butoxide pypéronyle Tax malation

Parasidose

Lotion pediculicide,
Lenticide
As above

Recurrence after treatment is, Can i have several origins) recontamination, ii) treatment misbehaving (Moreover, the application time recommended by the manufacturers is sometimes insufficient), iii) authentic resistance.

In practice, when properly performed treatment is failing, you have to change pharmacological class, for example, move from pyrethrum malathion, or vice versa.

If head lice, it is not necessary to treat the whole family but to monitor any siblings.

In case of body lice, disinfecting clothing and bedding is systematic, enough for some authors. It can be associated to treatment with pyrethrin or malathion.

The treatment of pediculosis pubis uses the same terms as the pediculosis of the scalp, but one of the drugs is more (pyrethrum, piperonyl butoxide en®spécifique : Spray spray-Pax). Pediculosis pubis requires the treatment of sexual partners. It's better to

treat all hairy areas of the thighs and trunk and sanitize the clothes. Shaving pubic hair may be needed if heavy slow.

E- Prevention :

Prophylaxis is based on good information and early detection of infected individuals. The preventive role of lice shampoos has never been demonstrated.

References :

  • skin ectoparasitosis. The review of the practitioner 2002,52,79-84.
  • Gale. In Parasitology-Mycology, ANOFEL, 6th edition, useful format, pages410-412.
  • Recognize mange and treat scabies 2002. The prescribing magazine 2002,22,450-455.
  • Treatment of Scabies. The review of the practitioner 2001,51,1281-1282.
  • ivermectin, new indication : against scabies, oral treatment, effective and easy to use. The prescribing magazine 2002,22,405- 409.
  • Support for scabies in health care facilities for the elderly. The letter from the infectious disease 2000, 8,351-357.
  • Lice and Crabs. In Parasitology-Mycology, ANOFEL, 6th editions, useful format, pages 415-418.
  • Head lice and head lice. The prescribing magazine 2000,21,761-770.
  • Lice are resisting. The letter from the infectious disease 2000, 8, 323-324.

Glossary :

  • mites : arthropods part of chelicerates (mouth provided with chelicera). They are equipped with 4 pairs of legs in the adult state, have a globular body without visible segmentation.
  • Insects : arthropods part of Mandibulata (mouth provided with mandibles), provided with 3 pairs of legs in the adult state, their bodies are segmented : head, thorax, abdomen. In general, their mobility is higher than that of mites.
  • ivermectin (Stromectol) : is the first oral drug marketed in France for treating scabies (Marketing authorization for this indication in 2001). Its effectiveness seems close to that topical scabicides. It could be particularly useful for the treatment of community outbreak of scabies. For several years, this drug is used as an anthelmintic

Courses of Dr. Bariout – Faculty of Constantine