Pediculosis Corporis

Etiology

Body lice are ectoparasites that must feed on human blood to survive and have a global distribution. They assume 3 forms across their life cycle, starting with the egg or nit, progressing to the nymph, and finally, the adult stage. As with head lice, nits are oval and appear yellow or white. However, body lice attach their eggs to the proximal hair shafts, unlike head lice, which lay their eggs in clothing seams. A nymph is an immature louse, which, except for its smaller size, has the same appearance as an adult louse. Adult lice have 6 legs, are tan to grayish-white in color and 2.5 to 3.5 cm in length, have no wings, and are flat in shape (see Image. Body Lice).

Body lice feed 1 to 5 times daily and can live up to 60 days. Body lice will die within a week after being separated from a human host. Recently, it has been established that severe iron deficiency anemia is linked with the development of pediculosis corporis.[3]

Epidemiology

As body lice cannot jump or fly, they spread primarily by direct contact, though transmission can also occur through clothing, bed linens, and towels. Infestations are strongly correlated with poor body hygiene, lack of access to clean clothing, and crowded conditions, facilitating lice spread through direct physical contact. Outbreaks most commonly occur in situations where large groups of people live in unsanitary conditions such as prisons or camps of large groups of refugees from war, famine, or natural disasters. In the United States and other developed countries, body lice infestations most commonly occur in homeless populations because of the lack of access to clean clothes or showers. Outbreaks of body lice infestations and louse-borne diseases continue to occur globally and have been documented in jails and refugee camps in central and eastern Africa, rural areas in the Peruvian Andes, and amongst rural populations in Russia.[2][4][5]

Pathophysiology

Body lice infestations can involve thousands of mites, each biting an average of 5 times daily. During feeding, body lice pierce the skin, inject a salivary anticoagulant, and then suck the blood meal into their digestive tract. Bites of the body louse can produce a variety of skin lesions, and severe pruritus is thought to be due to an allergic or inflammatory reaction to the louse's saliva.[6] Intense scratching of pruritic bites can result in skin excoriation, potentially leading to significant secondary bacterial infections.

The most significant medical impact of body lice is their ability to transmit bacterial diseases, most notably trench fever caused by Bartonella quintana, relapsing fever caused by Borrelia recurrentis, and epidemic (louse-borne) typhus caused by Rickettsia prowazekii.[7] Trench fever and epidemic typhus are transmitted not by louse bites but through infected feces. When feeding, the body louse often excretes feces onto the skin, which can be inadvertently rubbed into the bite site, eyes, or mucous membranes. Rickettsia prowazekii can also be transmitted through inhalation of aerosolized fecal dust, which has been documented as a potential source of infection for clinicians. Unlike trench fever and epidemic typhus, the transmission of relapsing fever, caused by Borrelia recurrentis, does not occur through contaminated feces. Infection occurs when a person crushes an infected louse, and the bacteria invade the bite site or the skin of the fingers or hand that crushed the louse.[7] In addition, a person can acquire the infection if they rub their eye or put their fingers in their mouth after crushing the louse.

Additional pathogenic bacteria in body lice include Salmonella typhi, Serratia marcescens, and Acinetobacter baumannii. The DNA of Yersinia pestis, which causes bubonic plague, has been identified in body lice, and it is believed they may serve as supplementary vectors for the organism.[1]

History and Physical

Historical clues such as poor body hygiene, lack of access to clean clothing, homelessness, and residing in crowded, unsanitary conditions should prompt consideration for body louse infestation and louse-borne infections. The primary symptom of body lice infestations is severe pruritus.

The dermatologic findings in body lice infestation vary but include pyoderma, erythematous macules, wheals, and hemorrhagic puncta. The severe pruritus of bites can cause intense scratching, leading to excoriations and secondary infections.[8] In chronic body lice infestation, frequently bitten areas of the skin can develop notable thickening and discoloration, a condition known as “vagabond’s disease.”[9] Dermatologic findings tend to be most prominent in areas where clothing seams are in contact with the skin, such as the waist, groin, thighs, and axillary folds.[6] Additional physical exam findings including cervical lymphadenopathy and conjunctivitis, are often present.

Unlike head and pubic lice, infestation with body lice is typically diagnosed by finding eggs and lice in seams of clothing rather than on the skin.[2] Therefore, an important exam component in patients suspected of having body lice includes careful inspection of their clothing. In addition to lice, indirect findings such as blood stains or louse feces may be discovered.[10]

Evaluation

While body lice may occasionally be found crawling on the patient’s skin, an infestation is typically diagnosed by finding eggs and lice in clothing seams. A PCR assay has been developed to differentiate between head and body lice but is primarily used for research purposes rather than to support clinical decision-making.

Treatment / Management

Treatment of body lice does not usually require the use of a pediculicide because improvements in hygiene, including showering and laundering clothing in hot water at least 50 °C, will most often eradicate the infestation.[2] All clothing, bed linens, and towels should be washed in hot water and machine-dried on the hot cycle.

Itching can be treated with topical corticosteroids and systemic antihistamines. Secondary skin infections are managed with appropriate systemic antibiotics. While pediculicides are not required to eradicate body lice infections, they are often used if body lice or nits are found on body hair or if there is a co-infection with head lice, pubic lice, or scabies.[6] In these cases, pharmacologic treatment employs the same agents for pubic and head lice, most commonly permethrin cream applied to the entire body for 8 to 10 hours. Additional treatments include 5% benzyl alcohol lotion, 0.5% ivermectin lotion, 0.5% malathion lotion, 0.9% spinosad topical suspension, and 1% lindane shampoo.[2][11] (B2)

Lindane is not recommended for first-line treatment due to some potentially serious reactions including neurotoxicity and seizures. In some settings, such as refugee camps with large numbers of people, environmental application of chemical insecticides may be needed to prevent the spread of body lice and louse-borne infections.[12][13][14](B3)

Differential Diagnosis

The differential diagnosis of dermatologic findings in body lice infestation includes scabies, contact dermatitis, atopic dermatitis, drug reaction, and viral exanthem. Co-infection with head lice, pubic lice, scabies, and fleas may be found, especially in refugee populations.[6]

A high index of suspicion should be maintained for trench fever, relapsing fever, and epidemic typhus in patients with body lice infestation presenting with signs or symptoms of systemic infections. Other infectious diseases with similar manifestations include babesiosis, brucellosis, Q fever, typhoid fever, leptospirosis, ehrlichiosis, and tularemia.

Prognosis

The prognosis for eradicating body lice infestation is excellent if patients shower regularly and have weekly access to laundered clothing and bedding. Significant morbidity and mortality are associated with louse-borne diseases but can be reduced substantially with early recognition and appropriate antibiotic therapy.

Epidemic typhus can cause vasculitis, leading to limb ischemia, gangrene, central nervous system (CNS) dysfunction, and multiorgan failure. Mortality ranges from 20% to 40% in untreated patients but decreases to 3% to 4% with appropriate antibiotic therapy.

Louse-borne, relapsing fever mortality rate is approximately 40% if untreated, while the mortality rate with treatment drops to around 4%.

Trench fever, caused by B. quintana, tends to be self-limited in immunocompetent people but can result in the development of endocarditis, which can lead to increased morbidity and mortality.

Complications

While body lice infestation does not usually lead to severe complications, there can be associated issues and secondary problems. Here are some potential complications of pediculosis corporis:

• Secondary Bacterial Infections: Constant scratching of the affected areas can lead to breaks in the skin, creating entry points for bacteria. This may result in secondary bacterial infections, such as impetigo or cellulitis. These infections can cause redness, swelling, and pus-filled lesions on the skin.

• Prurigo Nodularis: Chronic scratching can lead to the development of prurigo nodularis, a skin condition characterized by itchy nodules or papules. These nodules can be persistent and may require medical attention.

• Excoriations and Dermatitis: Scratching due to itching can cause excoriations (superficial wounds) and dermatitis. Persistent scratching can exacerbate inflammation and lead to more significant skin problems.

• Psychological Distress: Chronic infestations and the associated itching can cause significant psychological distress, leading to stress, anxiety, or depression in affected individuals. Social stigma and embarrassment may further contribute to psychological complications.

• Complications in Vulnerable Populations: Individuals who are already vulnerable, such as those with weakened immune systems, older adults, or those living in crowded or unsanitary conditions, may be more prone to complications. In such cases, the impact of body lice infestation can be more severe.

• Transmission of Pathogens: While body lice do not transmit diseases directly, their presence can indirectly contribute to transmitting specific bacterial pathogens. Body lice have been associated with transmitting diseases like trench fever, typhus, and relapsing fever. These diseases are more likely in conditions of poor hygiene and overcrowding.

• Anemia: In extreme cases of long-term and severe body lice infestation, blood loss due to repeated lice feedings could lead to anemia. However, this is a rare complication.