infestation with lice (see louse
). Lice live on the host's blood, obtained by piercing the skin and sucking the blood through the mouth part. The area bitten itches and may become sore and infected from scratching. Not only are lice an annoyance, but they also transmit some diseases, such as typhus.
Treatment. Head lice hatch eggs in silvery oval-shaped envelopes that attach to the shafts of the hairs. The eggs, called nits, can be removed with some difficulty by combing with a very fine-toothed comb. The lice and nits are effectively killed by applications of 1 per cent gamma benzene hexachloride (Kwell) in a cream or shampoo, lindane, permethrin cream or rinse, or pyrethrins and piperonyl butoxide liquid, gel, or shampoo.
infestation with lice of the species Phthirus pubis,
the crab louse, usually limited to the pubic hairs but sometimes involving other hairy areas such as the eyelashes, eyebrows, or axillae. It is usually transmitted sexually but may be contracted from bedding and clothing. On the body, it can be treated with a special cream, lotion, or shampoo, such as Kwell, twice daily for two weeks. If the eyelashes are involved, a thick layer of petrolatum should be applied. Called also crabs
pediculosis (pe-dik?u-lo'sis) [? + Gr. osis, condition]
A scalp infection caused by head lice, Pediculus humanus capitis
, a common parasite in children. Outbreaks are common in schools, esp. among children between the ages of 5 and 11. The infection is transmitted through use of personal items such as hair ornaments, combs, hairbrushes, hats, scarves, or coats or through direct contact between the heads of two children. Lice, which feed on blood obtained by biting the skin, cause itching, esp. around the ears, in the occipital area, and at the nape of the neck. Long-standing infestations may produce chronic inflammation. The adult louse is seen rarely; diagnosis usually is made through the presence of eggs (nits), which appear as whitish sacs attached to the hair. See: illustration
Itching and eczematous dermatitis. In long-standing, neglected cases, scratching may result in marked inflammation. Secondary infection by bacteria may occur, with formation of pustules, crusts, and suppuration. Hair may become matted and malodorous.
Therapies for lice infestations are modified frequently, to match the resistance of lice to current therapies and to minimize the toxicities of medications. Manual removal of lice always is appropriate and is strongly recommended by lice specialists. Others recommend the use of insecticides (pediculocides).
The patient and family are taught how to apply medication (lindane, permethrin, pyrethrins, piperonyl butoxide, malathion) to dry hair for lice and are warned that the eyes should be immediately flushed with copious amounts of water if the medication accidentally contacts them. They are informed about minimizing the spread of infection by washing or dry cleaning all clothing and linen used in the home, delousing of rugs and upholstered furniture with sprays or vacuuming, keeping combs and brushes separate, and using medicinal shampoos if there has been contact with the patient.
Pediculosis caused by the body louse, Pediculus humanus
. It is transmitted by direct contact or by wearing infested clothing and is often transmitted in crowded or unhygienic conditions. The body louse occasionally is the vector for several important transmissible illnesses, including epidemic typhus, trench fever, and relapsing fever.
Infestation with body lice is marked by intense itching, esp. on the neck, trunk, and thighs. Tiny hemorrhagic points identify the bites. Generalized excoriation, mild fever, and fatigue characterize heavy infestations. In severe cases, pustules may develop.
The patient first bathes with hot soap and water and then applies prescribed creams containing approved pesticides to affected areas.
The patient should be assessed for diseases that body lice may transmit. If the patient is homeless or impoverished, social services agencies should be contacted to assist him or her to find shelter and clean clothing. If the patient lives with others, close personal contacts or family members should be screened for lice. All clothing, furniture, rugs, and bedding must be washed with hot water or dry cleaned. To prevent transmission of pediculosis among hospitalized patients, all high-risk patients should be examined for evidence of hair or body lice infestation on admission. Health care professionals should be careful to include older adults who are dependent on others for care, those coming from nursing homes or other assisted living facilities, and people living in crowded conditions.
Infestation by lice of the eyebrows and eyelashes.
Pediculosis caused by Phthirus pubis, also known as crab lice. It is transmitted by direct contact and through bedding or shared towels. The pubic louse can also infest the axillae, eyelashes, and head hair. The patient can present with pruritus. On occasion visual identification of the lice may be seen in pubic hair as oval attachments on pubic hair shafts, black dots (feces) on skin and underwear, or crusts or scabs in pubic area from scratching. Treatment is the same as for other ectoparasitic (skin parasite) infestations.