INTRODUCTION — Pediculosis corporis, pediculosis pubis, and pediculosis capitis are disorders caused by infestation by one of three varieties of lice that specifically infest humans (figure 1). The organisms causing pediculosis corporis (Pediculus humanus humanus, also known as Pediculosis humanus corporis) and pediculosis capitis (Pediculus humanus capitis) are closely related variants of the same species. While pediculosis capitis is typically restricted to the scalp, patients with pediculosis corporis present with widespread symptoms, frequently involving the truncal areas.
The clinical findings, diagnosis, and treatment of pediculosis corporis will be discussed here. Pediculosis capitis and pediculosis pubis are reviewed separately. (See "Pediculosis capitis" and "Pediculosis pubis and pediculosis ciliaris".)
EPIDEMIOLOGY — Pediculosis corporis is a significant problem in countries where poverty, crowding, and a low level of personal hygiene favor spread and multiplication of the parasite. The communal bed is a major factor in the perpetuation of infestation. In Europe and North America, pediculosis corporis largely affects people who are homeless (particularly individuals not residing in shelters and without access to bathing facilities) [1].
PEDICULUS HUMANUS HUMANUS — The body louse (2 to 4 mm in length) is a little larger, but similar in morphology, to the head louse (figure 1 and picture 1A-B). Unlike the head louse, the body louse lives in clothing and lays eggs along the seams, rather than residing on the human host. The louse visits the host's skin to feed, and can survive for up to three days without a blood meal [2].
DISEASE TRANSMISSION — Pediculus humanus humanus serves as a vector for diseases such as epidemic typhus, trench fever, and relapsing fever [3-5]. Bartonella quintana transmission via louse infestation has also been linked to endocarditis [2]. (See "Endocarditis caused by Bartonella".)
CLINICAL MANIFESTATIONS AND DIAGNOSIS — Itching is the chief complaint, although some individuals do not seem to be troubled by the infestation. Signs may be limited to linear excoriations on the trunk and neck along with postinflammatory hyperpigmentation, sometimes with thickening or lichenification along areas of the involved trunk (picture 2A-B). Close inspection will sometimes reveal hemorrhagic puncta or wheals from fresh bites. Skin changes tend to be concentrated around the waist and in the axillary folds, areas where clothing seams contact the integument. The honey-like crusting and redness characteristic of secondary staphylococcal infection may also be present.
The diagnosis is made by identification of the louse or its nits (louse eggs) in clothing, especially in the seams. Less often, lice are seen crawling or feeding on skin (picture 3A-B). Lice may be visible with the naked eye, but a magnifying lens is helpful for finding lice and eggs [5].
The differential diagnosis often includes scabies, which can present with widespread pruritus and excoriations. Simultaneous infestation with body lice and scabies also may occur [2]. The identification of scabietic burrows and erythematous papules in classic areas of involvement (eg, web spaces of the fingers, wrists, and male genitalia) suggest the possibility of this diagnosis (picture 4A-B). Scabies mites are much smaller than lice, and are undetectable on examination with the naked eye. A skin scraping or dermoscopy may be used to assist in the diagnosis. (See "Scabies: Epidemiology, clinical features, and diagnosis".)
Atopic or contact dermatitis, pruritus secondary to systemic disease, and neurodermatitis may present with similar symptoms, and should also be considered in the differential diagnosis.
TREATMENT — The patient should be bathed thoroughly. Infested clothing and bed linen should be heat washed (temperature should reach at least 149°F), dry cleaned, or discarded [6,7]. Ironing clothing with particular attention to the seams will also kill lice on fabrics.
In most cases, the above methods are sufficient for the management of pediculosis corporis. Occasionally, a few nits will be found on body hair. For these patients, some authors recommend treatment with a topical pediculicide [2,7]. We suggest a single 8 to 10 hour application of permethrin 5% cream to the entire body [7]. Lindane lotion should not be used as a first-line therapy due to the potential for severe adverse events with this drug.
A low- to medium-potency topical corticosteroid cream applied to pruritic and irritated areas twice daily for a few days after elimination of lice provides symptomatic relief (table 1).
Although oral ivermectin therapy was associated with a dramatic reduction in the prevalence of body louse infestation in a cohort of men experiencing homelessness (28 of 33 men infested at day 0 versus 5 of 27 men at day 14), the effect was transient. Further studies are necessary to determine whether treatment with oral ivermectin should be recommended [8].
A randomized 45-day trial in which the effect of wearing permethrin-impregnated underwear was compared with placebo in 73 individuals with pediculosis corporis found only transient benefit from the treated underwear [9]. Although the intent-to-treat analysis revealed a greater likelihood of louse eradication at day 14 in the permethrin group (28 versus 9 percent), the difference between the two groups was no longer statistically significant at day 45 (28 versus 27 percent). In addition, an increase in permethrin-resistant body lice was detected in the permethrin group at the end of the study. The results of this study do not support the use of permethrin-treated underwear for body louse infestations.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Pediculosis".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topics (see "Patient education: Lice (The Basics)")
●Beyond the Basics topics (see "Patient education: Head lice (Beyond the Basics)" and "Patient education: Pubic lice (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Etiology – Pediculosis corporis is caused by infestation by the body louse. Unlike pediculosis capitis and pediculosis pubis, the organism lives on the clothing, rather than on the skin of infested individuals. The body louse can serve as a vector for epidemic typhus, trench fever, and relapsing fever. (See 'Pediculus humanus humanus' above.)
●Diagnosis – Patients with pediculosis corporis often complain of pruritus. Excoriations and postinflammatory hyperpigmentation are typical signs of infestation. The diagnosis is made through the visualization of lice or nits on clothing or skin. (See 'Clinical manifestations and diagnosis' above.)
●Treatment – Treatment of pediculosis corporis involves discarding, laundering (in hot water), or ironing infested clothing and bedding. These methods are often sufficient for eradication of the infestation. For patients who present with a few nits on body hair, we suggest the addition of treatment with permethrin 5% cream, rather than management of bedding and clothing alone (Grade 2C). (See 'Treatment' above.)
