What is body lice

Body lice are parasitic insects (Pediculus humanus var. corporis also called clothes lice) that live on clothing and bedding used by infested persons. Lice are insects that infest humans, causing a condition called pediculosis. Body lice frequently lay their eggs on or near the seams of clothing. Body lice are ectoparasites whose only host are humans. Body lice must feed on blood several times daily and usually only move to the skin to feed. The body louse resides close to the skin to maintain its body temperature. Body lice exist worldwide and infest people of all races. Infestation with body lice is uncommon in comparison to head lice. Body lice infestations can spread rapidly under crowded living conditions where hygiene is poor (the homeless, refugees, victims of war or natural disasters).

Body lice infestations (pediculosis) are spread most commonly by close person-to-person contact but are generally limited to persons who live under conditions of crowding and poor hygiene (for example, the homeless, refugees, etc.). Dogs, cats, and other pets do not play a role in the transmission of human lice. They cannot hop or fly.

In the United States, body lice infestations are found only in homeless transient populations who do not have access to bathing and regular changes of clean clothes. Infestation is unlikely to persist on anyone who bathes regularly and who has at least weekly access to freshly laundered clothing and bedding.

Adult body lice are 2.3–3.6 mm in length. Body lice live and lay eggs on clothing and only move to the skin to feed.

Intense itching (“pruritus”) and rash caused by an allergic reaction to louse bites are common symptoms of body lice infestation. As with other lice infestations, intense itching leads to scratching which can cause sores and secondary bacterial infection of the skin.

When body lice infestation is long lasting, heavily bitten areas of the skin can become thickened and darkened, particularly in the mid-section of the body. This condition is called “vagabond’s disease.”

Body lice are known to spread disease. Body lice can spread epidemic typhus, trench fever, and louse-borne relapsing fever.

Treating the body infested with lice is not usually necessary as the lice live on the clothing. Improved hygiene and access to regular changes of clean clothes is the only treatment needed for body lice infestations.

If the infestation is widespread and covers much of the body, insecticides used in the treatment of head lice may also used in the treatment of body lice.

Environmental measures are the focus of treating body louse infestations. Laundering of clothing and bed linens using hot washes is essential to killing body lice and their eggs on clothing.

Hot washing and hot tumble-drying is effective in killing lice and eggs.
Ironing with a hot iron is effective.
Dry cleaning is also effective.
Sometimes a topical insecticide spray can be applied to clothing, especially the seams.

Regular hot washing of clothes and bathing has led to a decrease in incidence of body lice but during wartime and in some undeveloped countries the condition can still occur. Household contacts and close friends should also be educated about hygiene and how to launder clothing and linen to prevent the spread of body lice and reinfestation.

How long can lice live off the body

Without blood meals, the body louse will die within 1 to 2 days off the host.

Where are body lice found?

Body lice generally are found on clothing and bedding used by infested people. Sometimes body lice are be seen on the body when they feed. Body lice eggs usually are seen in the seams of clothing or on bedding. Occasionally eggs are attached to body hair.

Lice found on the head and scalp are not body lice; they are head lice.

How are body lice spread?

Body lice are spread through direct physical contact with a person who has body lice or through contact with articles such as clothing, beds, bed linens, or towels that have been in contact with an infested person. In the United States, actual infestation with body lice tends to occur only in persons, such as homeless, transient persons, who do not have access to regular (at least weekly) bathing and changes of clean clothes, such as homeless, transient persons.

Can body lice transmit disease?

Yes. Body lice can spread epidemic typhus, trench fever, and louse-borne relapsing fever. Although louse-borne (epidemic) typhus is no longer widespread, outbreaks of this disease still occur during times of war, civil unrest, natural or man-made disasters, and in prisons where people live together in unsanitary conditions. Louse-borne typhus still exists in places where climate, chronic poverty, and social customs or war and social upheaval prevent regular changes and laundering of clothing.

What does body lice look like

Body lice have three forms: the egg (also called a nit), the nymph, and the adult.

Nit: Nits are lice eggs. Nits are laid by the adult female and are cemented at the base of the hair shaft nearest the skin. Viable eggs are usually located within 6 mm of the skin. They are hard to see and are often confused for dandruff. They are generally seen in the seams of an infested person’s clothing, particularly around the waistline and under armpits. Body lice nits occasionally also may be attached to body hair. They are 0.8 mm by 0.3 mm, oval and usually yellow to white in color. Body lice nits may take 1–2 weeks (range 6 to 9 days) to hatch.

Nymph: The egg hatches to release a nymph. The nit shell then becomes a more visible dull yellow and remains attached to the hair shaft. A nymph is an immature louse that hatches from the nit (egg). A nymph looks like an adult body louse, but is smaller, about the size of a pinhead. Nymphs mature into adults after three molts in about 7–12 days after hatching. To live, the nymph must feed on blood.

Adult: The adult body louse is about the size of a sesame seed, has 6 legs (each with claws), and is tan to greyish-white. Females lay eggs. To live, lice must feed on blood. If a louse falls off of a person, it dies within about 5–7 days at room temperature.

In persons with dark hair, the adult louse will appear darker. Females are usually larger than males and can lay up to 8 nits per day. Adult lice can live up to 30 days on a person’s body. To live, adult lice need to feed on blood several times daily. Without blood meals, the louse will die within 1 to 2 days off the host.

Figure 1. Body lice (stages) – Pediculus humanus humanus

body lice

Note: This image depicts five body lice, Pediculus humanus var. corporis, which from left to right, included three nymphal-staged lice, beginning with a stage N1, then N2, and thirdly a N3-staged nymph, followed by an adult male louse, and finally an adult female louse.

Complications of body lice infestation

Body lice infestations usually cause minimal problems. However, a body lice infestation sometimes leads to complications such as:

  • Secondary infections. When body lice scratch and dig to feed on your blood, they may irritate your skin. If you scratch to alleviate itching, this also can irritate your skin. If your skin becomes raw from these irritations, other infections may develop.
  • Skin changes. If you’re infested with body lice for a long time, you may experience skin changes such as thickening and discoloration — particularly around your waist, groin or upper thighs.
  • Spread of disease. Body lice can carry and spread some bacterial diseases, such as typhus, relapsing fever or trench fever.

Risk Factors for body lice

Body lice infestation is found worldwide but generally is limited to persons who live under conditions of crowding and poor hygiene who do not have access to regular bathing and changes of clean clothes, such as:

  • the homeless,
  • refugees and,
  • survivors of war or natural disasters.

Infestations can spread rapidly under such conditions. Body lice infestation can occur in people of all races.

Body lice are spread through direct contact with a person who has body lice or through contact with articles such as clothing, beds, bed linens, or towels that have been in contact with an infested person. However, in the United States, actual infestation with body lice tends to be occur only in homeless, transient persons who do not have access to regular bathing and changes of clean clothes.

Body lice can transmit disease. Epidemics of typhus and louse-borne relapsing fever have been caused by body lice (typically in areas where climate, poverty, and social customs or war and social upheaval prevent regular changes and laundering of clothing).

Prevention & Control of body lice

Body lice are spread most commonly by direct contact with an infested person or an infested person’s clothing or bedding. Body lice usually infest persons who do not launder and change their clothes regularly.

The following are steps that can be taken to help prevent and control the spread of body lice:

  • Bathe regularly and change into properly laundered clothes at least once a week; launder infested clothing at least once a week.
  • Machine wash and dry infested clothing and bedding using the hot water (at least 130°F) laundry cycle and the high heat drying cycle. Clothing and items that are not washable can be dry-cleaned OR sealed in a plastic bag and stored for 2 weeks.
  • Do not share clothing, beds, bedding, and towels used by an infested person.
  • Fumigation or dusting with chemical insecticides sometimes is necessary to control and prevent the spread of body lice for certain diseases (epidemic typhus).

Body lice signs and symptoms

Intense itching (“pruritus”) and rash caused by an allergic reaction to the louse bites are common symptoms of body lice infestation. When body lice infestation has been present for a long time, heavily bitten areas of the skin can become thickened and discolored, particularly around the midsection of the body (waist, groin, upper thighs); this condition is called “vagabond’s disease.”

As with other lice infestations, intense itching can lead to scratching which can cause sores on the body; these sores sometimes can become infected with bacteria or fungi.

How are body lice infestations diagnosed?

Body lice infestation is diagnosed by finding eggs and crawling lice in the seams of clothing. Sometimes a body louse can be seen on the skin crawling or feeding. Although body lice and nits can be large enough to be seen with the naked eye, sometimes a magnifying lens may be necessary to find lice or nits Diagnosis should be made by a health care provider if you are unsure about an infestation.

Body lice treatment

A body lice infestation is treated by improving the personal hygiene of the infested person, including assuring a regular (at least weekly) change of clean clothes. Clothing, bedding, and towels used by the infested person should be laundered using hot water (at least 130°F) and machine dried using the hot cycle.

Sometimes the infested person also is treated with a pediculicide, a medicine that can kill lice; however, a pediculicide generally is not necessary if hygiene is maintained and items are laundered appropriately at least once a week. A pediculicide should be applied exactly as directed on the bottle or by your physician.

Guidelines for the choice of the pediculicide are the same as for head lice.

How to get rid of body lice

Treatment for body lice and head lice is recommended for persons diagnosed with an active infestation. All household members and other close contacts should be checked; those persons with evidence of an active infestation should be treated. Some experts believe prophylactic treatment is prudent for persons who share the same bed with actively-infested individuals. All infested persons (household members and close contacts) and their bedmates should be treated at the same time.

Some pediculicides (medicines that kill lice) have an ovicidal effect (kill eggs). For pediculicides that are only weakly ovicidal or not ovicidal, routine retreatment is recommended. For those that are more strongly ovicidal, retreatment is recommended only if live (crawling) lice are still present several days after treatment (see recommendation for each medication). To be most effective, retreatment should occur after all eggs have hatched but before new eggs are produced.

When treating body lice and head lice, supplemental measures can be combined with recommended medicine (pharmacologic treatment); however, such additional (non-pharmacologic) measures generally are not required to eliminate a body lice and or head lice infestation. For example, hats, scarves, pillow cases, bedding, clothing, and towels worn or used by the infested person in the 2-day period just before treatment is started can be machine washed and dried using the hot water and hot air cycles because lice and eggs are killed by exposure for 5 minutes to temperatures greater than 53.5°C (128.3°F). Items that cannot be laundered may be dry-cleaned or sealed in a plastic bag for two weeks. Items such as hats, grooming aids, and towels that come in contact with the hair of an infested person should not be shared. Vacuuming furniture and floors can remove an infested person’s hairs that might have viable nits attached.

Treat the infested person(s): Requires using an Over-the-counter (OTC) or prescription medication. Follow these treatment steps:

  1. Before applying treatment, it may be helpful to remove clothing that can become wet or stained during treatment.
  2. Apply lice medicine, also called pediculicide, according to the instructions contained in the box or printed on the label. If the infested person has very long hair (longer than shoulder length), it may be necessary to use a second bottle. Pay special attention to instructions on the label or in the box regarding how long the medication should be left on the hair and how it should be washed out.
WARNING:

Do not use a combination shampoo/conditioner, or conditioner before using lice medicine. Do not re–wash the hair for 1–2 days after the lice medicine is removed.

  • Have the infested person put on clean clothing after treatment.
  • If a few live lice are still found 8–12 hours after treatment, but are moving more slowly than before, do not retreat. The medicine may take longer to kill all the lice. Comb dead and any remaining live lice out of the hair using a fine–toothed nit comb.
  • If, after 8–12 hours of treatment, no dead lice are found and lice seem as active as before, the medicine may not be working. Do not retreat until speaking with your health care provider; a different pediculicide may be necessary. If your health care provider recommends a different pediculicide, carefully follow the treatment instructions contained in the box or printed on the label.
  • Nit (head lice egg) combs, often found in lice medicine packages, should be used to comb nits and lice from the hair shaft. Many flea combs made for cats and dogs are also effective.
  • After each treatment, checking the hair and combing with a nit comb to remove nits and lice every 2–3 days may decrease the chance of self–reinfestation.
  • Continue to check for 2–3 weeks to be sure all lice and nits are gone. Nit removal is not needed when treating with spinosad topical suspension.
  • Retreatment is meant to kill any surviving hatched lice before they produce new eggs. For some drugs, retreatment is recommended routinely about a week after the first treatment (7–9 days, depending on the drug) and for others only if crawling lice are seen during this period. Retreatment with lindane shampoo is not recommended.

Supplemental Measures:

Body and head lice do not survive long if they fall off a person and cannot feed. You don’t need to spend a lot of time or money on housecleaning activities. Follow these steps to help avoid re–infestation by lice that have recently fallen off the hair or crawled onto clothing or furniture.

  • Machine wash and dry clothing, bed linens, and other items that the infested person wore or used during the 2 days before treatment using the hot water (130°F) laundry cycle and the high heat drying cycle. Clothing and items that are not washable can be dry–cleaned

OR

  • sealed in a plastic bag and stored for 2 weeks.
  • Soak combs and brushes in hot water (at least 130°F) for 5–10 minutes.
  • Vacuum the floor and furniture, particularly where the infested person sat or lay. However, the risk of getting infested by a louse that has fallen onto a rug or carpet or furniture is very small. Head lice survive less than 1–2 days if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the human scalp. Spending much time and money on housecleaning activities is not necessary to avoid reinfestation by lice or nits that may have fallen off the head or crawled onto furniture or clothing.
  • Do not use fumigant sprays; they can be toxic if inhaled or absorbed through the skin.

Over-the-counter Medications

Many head lice medications are available “Over-the-counter” without a prescription at a local drug store or pharmacy. Each Over-the-counter product approved by the FDA for the treatment of head lice contains one of the following active ingredients. If crawling lice are still seen after a full course of treatment contact your health care provider.

Pyrethrins combined with piperonyl butoxide

Brand name products: A–200*, Pronto*, R&C*, Rid*, Triple X*.

Pyrethrins are naturally occurring pyrethroid extracts from the chrysanthemum flower. Pyrethrins are safe and effective when used as directed. Pyrethrins can only kill live lice, not unhatched eggs (nits). A second treatment is recommended 9 to 10 days after the first treatment to kill any newly hatched lice before they can produce new eggs. Pyrethrins generally should not be used by persons who are allergic to chrysanthemums or ragweed. Pyrethrin is approved for use on children 2 years of age and older.

Permethrin lotion, 1%

Brand name product: Nix*.

Permethrin is a synthetic pyrethroid similar to naturally occurring pyrethrins. Permethrin lotion 1% is approved by the FDA for the treatment of head lice. Permethrin is safe and effective when used as directed. Permethrin kills live lice but not unhatched eggs. Permethrin may continue to kill newly hatched lice for several days after treatment. A second treatment often is necessary on day 9 to kill any newly hatched lice before they can produce new eggs. Permethrin is approved for use on children 2 months of age and older.

Prescription Medications

The following medications, in alphabetical order, approved by the U.S. Food and Drug Administration (FDA) for the treatment of head lice are available only by prescription. If crawling lice are still seen after a full course of treatment, contact your health care provider.

Benzyl alcohol lotion, 5%

Brand name product: Ulesfia lotion*

Benzyl alcohol is an aromatic alcohol. Benzyl alcohol lotion, 5% has been approved by the FDA for the treatment of head lice and is considered safe and effective when used as directed. It kills lice but it is not ovicidal. A second treatment is needed 7 days after the first treatment to kill any newly hatched lice before they can produce new eggs. Benzyl alcohol lotion is intended for use on persons who are 6 months of age and older and its safety in persons aged more 60 years has not been established. It can be irritating to the skin.

Ivermectin lotion, 0.5%

Brand name product: Sklice*

Ivermectin lotion, 0.5% was approved by the FDA in 2012 for treatment of head lice in persons 6 months of age and older. It is not ovicidal, but appears to prevent nymphs (newly hatched lice) from surviving. It is effective in most patients when given as a single application on dry hair without nit combing. It should not be used for retreatment without talking to a healthcare provider.

Given as a tablet in mass drug administrations, oral ivermectin has been used extensively and safely for over two decades in many countries to treat filarial worm infections. Although not FDA-approved for the treatment of lice, ivermectin tablets given in a single oral dose of 200 micrograms/kg or 400 micrograms/kg repeated in 9-10 days has been shown effective against head lice. It should not be used in children weighing less than 15 kg or in pregnant women.

Spinosad 0.9% topical suspension

Brand name product: Natroba*

Spinosad is derived from soil bacteria. Spinosad topical suspension, 0.9%, was approved by the FDA in 2011. Since it kills live lice as well as unhatched eggs, retreatment is usually not needed. Nit combing is not required. Spinosad topical suspension is approved for the treatment of children 6 months of age and older. It is safe and effective when used as directed. Repeat treatment should be given only if live (crawling) lice are seen 7 days after the first treatment.

Malathion lotion, 0.5%

Brand name product: Ovide*

Malathion is an organophosphate. The formulation of malathion approved in the United States for the treatment of head lice is a lotion that is safe and effective when used as directed. Malathion is pediculicidal (kills live lice) and partially ovicidal (kills some lice eggs). A second treatment is recommended if live lice still are present 7–9 days after treatment. Malathion is intended for use on persons 6 years of age and older. Malathion can be irritating to the skin. Malathion lotion is flammable; do not smoke or use electrical heat sources, including hair dryers, curlers, and curling or flat irons, when applying malathion lotion and while the hair is wet.

What steps do I follow to treat with malathion?

Step 1: Treat the person(s) infested with head lice:

  1. Always follow your physician’s and pharmacist’s instructions and those contained inside the package or written on the label.
  2. Carefully apply the malathion lotion to dry hair until the scalp and hair are wet and thoroughly coated, especially behind the ears and on the back of the head and neck.
  3. The manufacturer recommends leaving the medication on the hair, uncovered, for 8–12 hours. Allow the hair to dry naturally; do not use an electrical heat source, including a hair dryer or curling iron while the hair is wet. Have the person being treated put on clean clothing once the medication has been applied. Consider treating just before bedtime. Cover any pillow(s) with a towel to keep the medication from staining the pillow.
  4. After 8–12 hours, thoroughly shampoo the hair; rinse and use a fine-toothed nit comb, usually included in the package, to remove dead lice and nits from the hair.
  5. After treatment, use a fine-toothed nit comb to check the hair for live lice every 2–3 days for 2–3 weeks until sure that all lice are gone.
  6. If live lice are found 7 to 9 days after treatment, retreat with a second application of the same medication.

Warnings and Precautions:

  1. Malathion may cause stinging, especially if the scalp has open sores from scratching.
  2. Keep medication out of the eyes.
  3. Malathion is flammable; keep medication and wet hair away from heat sources such as hair dryers, electric curlers, cigarettes, or open flames.
  4. Pregnant and nursing mothers should use malathion only after consulting their physician.

Step 2: Consider additional household measures:

Body and head lice do not live long (less than 1–2 days) if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the human scalp. You do not need to spend a lot of time or money on housecleaning activities. Follow these steps to help avoid re-infestation by live lice or nits that may have recently fallen off the head or crawled onto clothing or furniture.

  • To kill lice and nits that may have fallen or crawled off the head onto clothing or other articles, machine wash clothing, bed linens, and other items (e.g. towels, stuffed animals, comforters, blankets, etc.) that the infested person wore, slept on, or used during the 2 days before treatment. Use the hot water (at least 130°F) cycle. Dry the laundry using the high heat setting for at least 20 minutes. Items that are not washable can be dry-cleaned.

OR

  • stored in a sealed plastic bag for 2 weeks.
  • Soak combs and brushes in hot water (at least 130°F) for 5–10 minutes.
  • Vacuum the floor and furniture, particularly where the infested person sat or lay. However, the risk of getting infested by a louse or a nit that was attached to a shed hair that has fallen onto a carpet or furniture is very small. Head lice survive less than 1–2 days if they fall off a person and cannot feed; nits cannot hatch and usually die within a week if they are not kept at the same temperature as that found close to the human scalp. Spending much time and money on housecleaning activities is not necessary to avoid reinfestation by lice that have crawled or nits on shed hairs that may have fallen off the head.
  • Do not use fumigant sprays; they can be toxic if inhaled or absorbed through the skin.

Step 3: Prevent Reinfestation:

Lice are spread most commonly by direct head-to-head (hair-to-hair) or for body lice body-to-body contact and much less frequently by sharing clothing, beds, bed linens, towels or belongings onto which lice or nits may have crawled or fallen. Teach children to avoid types of play and other activities that may spread lice.

  • Avoid head-to-head (hair-to-hair) contact during play and other activities at home, school, and elsewhere (slumber parties, sports activities, camp, playground).
  • Do not share clothing such as hats, scarves, coats, sports uniforms, hair ribbons, or barrettes.
  • Do not share combs, brushes, or towels.
  • Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with an infested person.

For second–line treatment only:

Lindane shampoo 1%

Brand name products: None available

Lindane is an organochloride. The American Academy of Pediatrics no longer recommends it as a pediculocide. Although lindane shampoo 1% is approved by the FDA for the treatment of head lice, it is not recommended as a first–line treatment. Overuse, misuse, or accidentally swallowing lindane can be toxic to the brain and other parts of the nervous system; its use should be restricted to patients for whom prior treatments have failed or who cannot tolerate other medications that pose less risk. Lindane should not be used to treat premature infants, persons with HIV, a seizure disorder, women who are pregnant or breast–feeding, persons who have very irritated skin or sores where the lindane will be applied, infants, children, the elderly, and persons who weigh less than 110 pounds. Retreatment should be avoided.

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