Body Lice

Body lice (pediculosis corporis) is caused by Pediculus humanus corporis (also called Pediculus humanus humanus), a subspecies of the human louse that can interbreed with head lice biologically but is an entirely distinct clinical and epidemiological condition: unlike head lice (Pediculus humanus capitis) and pubic lice (Phthirus pubis), which live directly on the host, body lice live and lay their eggs (nits) in the seams and folds of worn clothing and bedding, leaving that habitat only to take a blood meal from the skin several times a day before returning to the fabric.^[1]

This single fact drives almost everything distinctive about the condition. Body lice infestation occurs specifically where clothing is worn for extended periods without laundering or changing — a marker of limited access to regular bathing and clean clothing rather than a failure of personal hygiene — and is essentially unheard of in people with reliable, regular access to laundry facilities.^[1] It is also the clinically most consequential of the three human lice, because the body louse — and only the body louse — is a proven vector for three serious systemic bacterial diseases: epidemic typhus (Rickettsia prowazekii), trench fever (Bartonella quintana), and louse-borne relapsing fever (Borrelia recurrentis).^[2][3] A 2020-2021 surveillance study of persons experiencing homelessness in inner-city Winnipeg, led by the Public Health Agency of Canada, found body lice positive for B. quintana in 1 of 7 participants sampled — a concrete reminder that these pathogens are a real, current concern in Canadian shelter and street-involved populations, not only a historical or overseas one.^[4]

This chapter covers body lice only. Head lice and pubic lice have different habitats, transmission routes, and management, and are covered in their own separate chapters.

Symptoms

Intense, often relentless pruritus is the dominant and usually the presenting symptom, typically most severe over the trunk, shoulders, waist, and axillae — the areas where clothing seams contact skin most consistently — and commonly precedes any visible skin change.^[1]

Skin findings

Bite reactions appear as erythematous macules, papules, or wheals with a central hemorrhagic punctum, concentrated in the areas above. Scratching commonly produces excoriations, and secondary bacterial infection (impetigo, cellulitis) is a genuine and common complication of chronic scratching, not a rare one.^[1]

Vagabond's disease — the mark of a chronic, longstanding infestation

With prolonged, untreated infestation, repeated bites and scratching over the same clothing-contact areas — waist, groin, axillae, shoulders, upper back — produce a distinctive pattern of thickened, hyperpigmented, lichenified skin historically termed "vagabond's disease" (morbus errorum). Its presence signals a chronic infestation, not a recent or trivial one, and should prompt a direct, practical conversation about the patient's actual ongoing access to clean clothing and bathing rather than being treated as simply a more severe rash.^[1]

Extensive body lice infestation — the excoriations and hyperpigmentation of chronic infestation are visible on the skin, while the "dusty dots" along the clothing seams are adult lice. This is the diagnostic hallmark of body lice: the infestation lives in the clothing, not on the skin or in hair. (Image: DermNet NZ, Pediculosis image library, dermnetnz.org)

Other findings

Cervical or regional lymphadenopathy and mild conjunctivitis are occasionally seen with heavier infestations. Lice or nits are only rarely found directly on body hair, and only with heavy, longstanding infestation — see Assessment & Diagnosis for where to actually look first.^[1]

• Homelessness or unstably housed/unsheltered living — the dominant risk factor, driven by limited access to regular bathing and clean-clothing changes rather than by any personal characteristic of the individual.^[1]
• Crowded congregate settings with shared or infrequently laundered bedding/clothing — homeless shelters, refugee camps, and correctional facilities.^[1]
• Situations of social disruption, displacement, or disaster response that interrupt normal access to laundry and bathing facilities, including historically war and mass population displacement — the setting in which epidemic typhus has caused its largest historical outbreaks.^[5]
• Cold-climate settings where layered clothing is worn for extended periods without changing — a practical Canadian consideration for unsheltered individuals over the winter months.
• Severe poverty limiting access to a change of clothing or to laundry facilities/services.
• Chronic mental illness or substance use disorder, where these compound existing barriers to stable housing, bathing, and clothing access.
• Older age or reduced mobility/functional capacity limiting a person's ability to independently bathe or launder clothing.
• Any circumstance producing prolonged, unchanged use of the same clothing — this is the common final pathway across every risk factor above, not any one of them individually.

History

Ask directly, and without judgment, about the patient's actual current access to regular bathing and to laundering or changing clothing — housing status, shelter stays, and how frequently clothing is realistically changed are the most clinically relevant history here, more so than a general hygiene history.^[1] Characterize the itching (onset, distribution, severity) and ask specifically about fever, rash, or joint pain in the recent past, since these change the encounter from a skin complaint into a possible systemic-infection assessment (see Red Flags & Refer).

Examination — look at the clothing, not just the skin

This is the central diagnostic pearl for body lice and the point most likely to be missed: body lice and their nits are found in the seams and folds of worn clothing, not on the skin or in hair.^[1] With the patient's consent and in a private setting, examine the inner seams of the waistband, underarms, collar, and any other area of prolonged skin contact for live lice, nits glued to the fabric fibres, and small dark fecal specks — a magnifying lens is helpful for a light infestation. Blood staining on the fabric from feeding or scratching may also be visible. Only with heavy, longstanding infestation are lice occasionally also found directly on body hair — check for this specifically, since it changes management (see Choose Initial Treatment).^[1]

On skin examination, look for the bite reactions, excoriations, and — in chronic infestation — the hyperpigmented, thickened skin of vagabond's disease described in Recognize the Condition.

Differential diagnosis

Laboratory testing

No routine laboratory testing is needed to diagnose uncomplicated body lice — diagnosis is clinical, made by direct visualization on the clothing. Reserve testing for a patient with red-flag features suggesting a louse-borne systemic illness: paired acute/convalescent IFA serology or PCR for R. prowazekii; dark-field microscopy, a Giemsa-, Wright-, or acridine-orange-stained blood/bone marrow smear, or EIA serology for B. recurrentis; and blood culture or serology for B. quintana (an IgG titre over 1:800 predicts endocarditis).^[5][7][2]

• Eliminate the louse population by decontaminating the actual clothing and bedding where lice and nits live — this is the primary, essential target of therapy, not an adjunct to a topical medication.
• Relieve pruritus and treat any secondary bacterial skin infection.
• Identify and treat body-hair infestation with a topical pediculicide specifically when lice or nits are actually found there, rather than by default.
• Recognize and urgently treat or refer any suspected louse-borne systemic illness — epidemic typhus, trench fever, or louse-borne relapsing fever — and meet the applicable public health notification requirement.
• Connect the patient with a genuinely sustainable source of clean clothing and bathing/laundering access, since this — not any medication — is what actually prevents recurrence.
• Deliver every part of this care in a respectful, non-stigmatizing way that treats body lice as a treatable medical condition tied to an access barrier, not a personal failing.

When a topical pediculicide is actually needed

Preferred, when lice or nits are found on body hair permethrin 1% creme rinse applied to the affected hair-bearing skin, left in place for 10 minutes, then rinsed off; repeat in 7-9 days if live lice are still seen — the same standard dosing used for head lice. Do not apply a pediculicide to intact, uninvolved skin, and do not use it as a substitute for clothing/bedding decontamination — a pediculicide alone, without laundering, does not clear a body lice infestation, because the louse population lives in the clothing, not on the person.^[1] Alternative malathion 0.5% lotion applied to affected hair-bearing skin for 8-12 hours then washed off, reserved for permethrin-refractory infestation given its odour and flammability (avoid open flame or a hair dryer during use). Special situation oral ivermectin (used off-label; not a Health Canada-approved indication for lice) has been used for outbreak control in shelter settings where topical application to many residents at once is impractical — reserve for this specific situation, generally with specialist or public health input.

Symptomatic care

Pruritus a non-sedating oral antihistamine (cetirizine) for daytime use, or diphenhydramine at bedtime if nocturnal itching is prominent. Inflamed, excoriated skin a short course of low-potency topical hydrocortisone. Secondary bacterial skin infection treat per the usual impetigo/cellulitis pathway if present.

Suspected louse-borne systemic illness — treat urgently and notify public health

Suspected epidemic typhus doxycycline 100 mg PO twice daily until afebrile for 24-48 hours, typically 7-10 days total; chloramphenicol 500 mg PO/IV four times daily for 7-10 days is a documented alternative. Start treatment without waiting for serologic confirmation if the patient is seriously ill — early treatment essentially eliminates the risk of fatal illness.^[5][6]

Suspected louse-borne relapsing fever a single dose of doxycycline 200 mg PO is the standard treatment specifically for louse-transmitted disease — genuinely different from, and much shorter than, the 10-day course used for tick-borne relapsing fever; tetracycline or erythromycin 500 mg PO as a single dose is a documented alternative.^[8] Premedicating with acetaminophen 650 mg PO given 2 hours before and repeated 2 hours after the antibiotic dose has been used to reduce the severity of the Jarisch-Herxheimer reaction, which occurs in over half of patients and can include acute hemodynamic instability — treat in a setting equipped to monitor for and manage this reaction regardless of the specific antibiotic chosen, being prepared to resuscitate through the reaction rather than to withhold treatment.^[8][3]

Suspected trench fever / Bartonella quintana bacteremia doxycycline 200 mg/day PO for 28 days combined with gentamicin 3 mg/kg/day IV for 14 days; for endocarditis, extend doxycycline to 6 weeks (100 mg PO twice daily) with the same 14-day gentamicin course — combination therapy with an aminoglycoside is associated with better clearance of bacteremia and better survival than doxycycline alone. If aminoglycoside toxicity is a specific concern, involve infectious diseases to select an alternative combination rather than simply omitting gentamicin without substitution.^[2]

Clothing and bedding decontamination — the core, non-negotiable intervention

• Hot-water wash plus high-heat dry for all clothing, bedding, and towels the patient has actually been wearing/using — at least 50°C (130°F) wash, followed by a full high-heat dry cycle.^[1]
• Dry cleaning for items that cannot be machine washed.
• Sealed plastic bag for at least 2 weeks for items that can be neither washed nor dry-cleaned — lice die without a blood meal well within this window, and any remaining eggs will have hatched and died as well.^[1]
• A single high-heat dryer cycle (at least 30 minutes) alone is a reasonable rapid option when laundering the item is genuinely not possible in the short term.
• Discard heavily infested items outright when a replacement can realistically be provided — many shelters and outreach programs can supply clean replacement clothing, which is often more practical than asking a patient to manage a multi-step decontamination process with very limited belongings.
• Body lice are not a broad household or furniture infestation the way bed bugs are — decontamination should focus specifically on the person's actual worn clothing and bedding, not on fumigating a living space.

Personal hygiene

Regular bathing or showering, together with a genuine, ongoing change of clean clothing (ideally at least weekly), is on its own sufficient to control body lice, and is the single most important preventer of recurrence.^[1]

Addressing the access barrier — the actual determinant of whether treatment succeeds

Because body lice infestation is fundamentally a marker of limited access to bathing and clean clothing rather than a personal hygiene failure, a course of pediculicide or even a single successful laundering event will not prevent reinfestation if that underlying access barrier remains. Connect the patient with practical resources: shelter or drop-in laundry and shower facilities, clean-clothing exchange or donation programs, and outreach or public health nursing services already working with the local homeless-serving system. In congregate settings (shelters, correctional facilities), work with facility staff on routine screening and laundering protocols for residents, consistent with local public health infection-prevention-and-control guidance for these settings.

A non-stigmatizing approach

Frame body lice explicitly as a treatable medical condition tied to a real, addressable access barrier, not as a reflection of the patient's character or effort. Patients who have previously been shamed for a lice infestation are less likely to seek care early or to disclose ongoing symptoms — a matter-of-fact, practical approach measurably improves both the immediate encounter and the likelihood of a successful, lasting outcome.

Pregnancy

Favor non-pharmacologic management (clothing/bedding decontamination and hygiene access) as the primary approach in pregnancy, since this alone resolves most infestations. If a topical pediculicide is genuinely needed permethrin is generally preferred among pediculicide options in pregnancy, since only minimal systemic absorption occurs with topical use and animal studies at oral doses far higher than typical topical exposure have not shown fetal harm, though adequate controlled human studies are lacking.

Suspected louse-borne systemic illness in pregnancy do not withhold treatment for a genuinely life-threatening maternal infection. Louse-borne relapsing fever in particular carries a very high rate of adverse pregnancy outcomes — miscarriage, stillbirth, preterm delivery, or suspected congenital infection in roughly 3 of 4 reported pregnancies — so treating the maternal infection is itself protective of the pregnancy.^[3] Involve obstetrics and infectious diseases immediately for antibiotic selection and monitoring in this situation.

Breastfeeding

Topical permethrin is considered compatible with breastfeeding given minimal systemic absorption. Short courses of doxycycline for a genuine systemic indication are generally considered compatible with breastfeeding by current expert sources, given limited calcium-mediated transfer into the infant through breast milk, though this should still be confirmed against the current product monograph and guidance at the time of use.

Pediatrics

Children in families experiencing homelessness or housing instability are also at risk and should be screened alongside affected adults. Confirm the age-appropriate minimum for any topical pediculicide against its product monograph before use in a young child. The decontamination approach (hot laundering, dry cleaning, or 2-week bagging) is identical regardless of age.

Older adults

Use diphenhydramine cautiously given its anticholinergic burden; cetirizine is generally the better-tolerated antihistamine choice in this group. Chronic vagabond's-disease skin changes and reduced skin integrity may make this population more prone to secondary bacterial infection from scratching — examine skin carefully.

Immunocompromised patients, including HIV

Maintain a lower threshold to investigate for a louse-borne systemic illness, since presentation can be more severe or atypical, and involve infectious diseases early.

Renal impairment

Adjust the gentamicin dose to renal function and monitor levels closely when it is used for confirmed B. quintana bacteremia or endocarditis — this combination is specifically valuable but carries real nephrotoxicity risk. Doxycycline generally requires no renal dose adjustment.

Arrange follow-up at 1-2 weeks to confirm the infestation has actually resolved and, just as importantly, that clothing/bedding decontamination was genuinely achievable for the patient — ask directly rather than assuming, and offer further practical support (shelter laundry access, replacement clothing) if a barrier remains.

• Re-examine clothing seams for any persistent live lice or new nits.
• Assess skin healing and resolution of pruritus; screen for signs of secondary infection that may have developed after the initial visit.
• If a topical pediculicide was used for body-hair involvement, confirm whether retreatment at day 7-9 is indicated per the product's standard dosing schedule.
• Screen specifically for any interval fever, rash, or other systemic symptom at every follow-up contact — a louse-borne systemic illness can present after the skin infestation has already been treated.
• For any patient treated for epidemic typhus, trench fever, or louse-borne relapsing fever, confirm the full course was completed, that specialist follow-up (infectious diseases, and cardiology if endocarditis was involved) is arranged, and that the applicable public health notification and any required contact follow-up has actually been completed.^[5][7]
• Beyond the immediate episode, the most important ongoing "monitoring" question is whether the patient now has a durable connection to clean clothing and bathing access — reassess and re-engage this at every subsequent contact, since it is what determines whether the infestation recurs.

1. Persistent itching or live lice after an apparent treatment attempt: confirm — directly and specifically — that every worn item of clothing and bedding was actually laundered at an adequate temperature (or dry-cleaned, or sealed for the full 2 weeks) rather than assuming a partial effort was sufficient; most apparent "failures" reflect incomplete decontamination of all the patient's actual belongings, not pediculicide resistance.
2. An ongoing, unresolved access barrier to laundering or bathing: escalate to practical social supports (shelter laundry/shower access, a clean-clothing exchange program, outreach nursing) rather than simply repeating the same advice or a pediculicide course.
3. Lice or nits still present on body hair after one course of permethrin: retreat at day 7-9 per standard dosing, or switch to malathion (or, in an outbreak/shelter setting, consider oral ivermectin) if resistance is suspected.
4. New or persistent fever, rash, or other systemic symptoms despite apparently successful clothing decontamination: reassess for an already-established louse-borne infection (typhus, trench fever, relapsing fever) that predates the treatment episode — treat and notify public health per Red Flags & Refer rather than assuming ongoing skin symptoms explain the systemic findings.
5. Prompt reinfestation shortly after apparently successful treatment: this is almost always re-exposure from an untreated shared living environment or an item that was missed, not a failure of the decontamination method itself — identify and address the actual source.
6. A secondary skin infection not improving on the initial antibiotic choice: reassess for an alternative or resistant organism and escalate per the usual skin and soft tissue infection pathway.

• Treating body lice with a topical pediculicide alone while never addressing clothing and bedding decontamination — since the lice population lives in the fabric, this leaves the actual source of the infestation untouched.
• Examining only the skin and hair, rather than the clothing seams, and missing the diagnosis (or misdiagnosing something else) as a result.
• Applying a pediculicide to intact skin by default rather than confirming lice or nits are genuinely present on body hair first.
• Using stigmatizing or moralizing language when discussing the diagnosis, which reduces the likelihood of early presentation and honest disclosure of ongoing symptoms.
• Attributing fever or a rash in a patient with body lice exposure to the skin infestation itself, rather than screening for epidemic typhus, trench fever, or louse-borne relapsing fever.
• Failing to notify public health when a louse-borne systemic illness is suspected or confirmed, or assuming this reporting requirement does not apply simply because typhus is not nationally notifiable in Canada — check and follow the specific notifiable-disease requirement in your own province or territory.
• Starting antibiotic treatment for suspected louse-borne relapsing fever without preparing to monitor for and manage the Jarisch-Herxheimer reaction, which occurs in over half of patients.
• Confusing body lice with head lice or pubic lice and applying a mismatched treatment (e.g., treating the scalp or pubic hair) when the actual infestation is in worn clothing.
• Recommending broad insecticide fumigation of a patient's living space — the mainstay of treatment is laundering the person's actual worn clothing and bedding, not treating furniture or the wider environment.
• Treating a single successful decontamination episode as the end of the encounter without addressing the patient's ongoing, real-world access to bathing and clean clothing, which is what actually prevents recurrence.

How to use this table: doses are adult doses and require patient-specific confirmation, including renal/hepatic adjustment. Select any drug name to open its complete Pharmasist Drug Database page.

Topical Pediculicides — For Confirmed Lice or Nits on Body Hair Only

Clothing and bedding decontamination is the actual core of treatment for body lice; a pediculicide is an adjunct used only when lice or nits are genuinely found on body hair, never a substitute for it.

Symptomatic Relief

Epidemic Typhus (Rickettsia prowazekii) — Systemic Antibiotic Therapy

Start treatment without waiting for laboratory confirmation if the patient is seriously ill; early treatment essentially eliminates the risk of fatal illness. This is a reportable illness — notify public health.

Trench Fever (Bartonella quintana) — Systemic Antibiotic Therapy

Combination therapy with an aminoglycoside improves bacteremia clearance and survival compared with doxycycline alone, particularly in endocarditis.

Louse-Borne Relapsing Fever (Borrelia recurrentis) — Systemic Antibiotic Therapy

The louse-borne-specific single-dose regimen is genuinely different from, and much shorter than, the multi-day course used for tick-borne relapsing fever. Treat only in a setting equipped to monitor for and manage the Jarisch-Herxheimer reaction, which occurs in over half of patients.