Pediculosis - Causes, Symptoms and Treatments:
Pediculosis is caused by parasitic forms of lice: Pediculus humanus var. capitis causes pediculosis capitis (head lice); Pediculus humanus var. corporis causes pediculosis corporis (body lice); and Phthirus pubis causes pediculosis pubis (crab lice). These lice feed on human blood and lay their eggs (nits) in body hairs or clothing fibers.
After the nits hatch, the lice must feed within 24 hours or die; they mature in about 2 to 3 weeks. When a louse bites, it injects a toxin into the skin that produces mild irritation and a purpuric spot. Repeated bites cause sensitization to the toxin, leading to more serious inflammation. Treatment can effectively eliminate lice.
Causes of Pediculosis:
P. humanus var. capitis (most common species) feeds on the scalp and, rarely, in the eyebrows, eyelashes, and beard. This form of pediculosis is caused by overcrowded conditions and poor personal hygiene, and commonly affects children, especially girls. It spreads through shared clothing, hats, combs, and hairbrushes.
P. human us var. corporis lives in the seams of clothing, next to the skin, leaving only to feed on blood. Common causes include prolonged wearing of the same clothing (which might occur in cold climates), overcrowding, and poor personal hygiene. It spreads through shared clothing and bedsheets.
P. pubis is primarily found in pubic hairs, but this species may extend to the eyebrows, eyelashes, and axillary or body hair. Pcdiculosis pubis is transmitted through sexual intercourse or by contact with clothes, bedsheets, or towels harboring lice.
Signs and symptoms of Pediculosis:
Clinical features vary with the cause. Signs and symptoms of pediculosis capitis include itching; excoriation (with severe itching); matted, foul-smelling, lusterless hair (in severe cases); occipital and cervical lymphadenopathy; and a rash on the trunk probably due to sensitization. Adult lice migrate from the scalp and deposit oval gray-white nits on hair shafts.
Pediculosis corporis initially produces small red papules (usually on the shoulders, trunk, or buttocks). Later wheals (probably a sensitivity reaction) may develop. Untreated pediculosis corporis may lead to vertical excoriations and ultimately to dry, discolored, thickly encrusted, scaly skin, with bacterial infection and scarring. In severe cases, headache, fever, and malaise may accompany cutaneous symptoms.
Pediculosis pubis causes skin irritation from scratching, which is usually more obvious than the bites. Small gray-blue spots (maculae caeruleae) may appear on the thighs or upper body.
Diagnosis for Pediculosis:
Pediculosis is visiblc on physical examination as follows:
. in pediculosis capitis there are oval grayish nits that can't be shaken loose like dandruff (the closer the nits are to the end of the hair shaft, the longer the infection has been present, because the ova are laid close to the scalp)
. in pediculosis corporis there are characteristic skin lesions with nits found on clothing
* in pediculosis pubis nits are attached to pubic hairs, which feel coarse and grainy to the touch. Other conditions to consider are dandruff, impetigo, and scabies.
Treatment for Pediculosis:
For pediculosis capitis, treatment consists of permethrin cream rinse rubbed into the hair and rinsed after 10 minutes. A single treatment should be sufficient. Use oflindane has been questioned because of a significant failure rate and concerns regarding neurotoxicity. Removing nits with a fine-tooth comb dipped in vinegar is vital; washing hair with ordinary shampoo removes encrustations.
Pediculosis corporis requires bathing with soap and water to remove lice from the body. Lice may be removed from clothes by washing them in hot water, ironing, or dry-cleaning. Storing clothes for more than 30 days or placing them in dry heat of 140 F (60 C) kills lice. If clothes can't be washed or changed, application of 10% lindane powder is effective.
Treatment of pediculosis pubis includes application of a topical pediculocide. Various agents such as 0.5% malathion emulsion, permethrin cream, and lindane ointment have been used according to the patient's status and health care provider's preference. Clothes and bedsheets must be laundered to prevent reinfestation.
Special considerations of Pediculosis:
. Instruct patients how to use the creams, ointments, powders, and shampoos that can eliminate lice. To prevent self infestation, avoid prolonged contact with the patient's hair, clothing, and bedsheets.
. Ask the patient with pediculosis pubis for a history of recent sexual contacts, so that they can be examined and treated.
. To prevent the spread of pediculosis to other hospitalized persons, examine all high-risk patients on admission, especially the elderly who depend on others for care, those admitted from nursing homes, or persons living in crowded conditions.
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