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Emergency and Acute Medicine – Pediculosis
Pediculosis is an infestation caused by lice that live in close association with humans. Bites are typically painless, and symptoms arise from the host’s inflammatory response to saliva and anticoagulants injected during feeding. Transmission occurs through direct contact and fomites such as combs, pillows, hats, and clothing. Head lice spread primarily through head-to-head contact and are more common in children and females. Pubic lice are usually transmitted through sexual contact. All lice are obligate human parasites and generally cannot survive away from a host for more than 7–10 days.
The condition is caused by three main species. *Pediculus capitis* (head lice) is the most common and affects all socioeconomic groups. *Pediculus corporis* (body lice) is associated with poor hygiene, poverty, and overcrowding, living primarily in clothing seams and transferring to the skin for feeding. *Phthirus pubis* (pubic or crab lice) typically infests coarse hair in the pubic region and is sexually transmitted. In children, pubic lice should raise concern for possible sexual abuse.
Clinical presentation varies by type. Head lice may cause scalp pruritus or be asymptomatic, often mistaken for dandruff. Body lice present with pruritus and excoriations, especially along clothing seams. Pubic lice cause intense itching, often worse at night. Physical examination focuses on identifying live lice or nits cemented to hair shafts, which cannot be easily brushed off. Empty nits alone do not confirm active infestation. Findings may include erythema, excoriations, secondary bacterial infection, posterior cervical lymphadenopathy, or bluish macules (maculae ceruleae) in pubic lice. Body lice are confirmed by finding nits in clothing seams rather than on the skin.
Diagnosis is clinical, based on careful history and physical examination with universal precautions. Laboratory testing is rarely necessary, although nits may be visualized under low-power microscopy and may fluoresce under a Wood lamp. Imaging has no role. Differential diagnoses include scabies, contact or allergic dermatitis, seborrheic dermatitis, and bed bug bites.
Management is primarily outpatient and supportive. Pruritus may be relieved with oral antihistamines or topical steroids. Head lice are treated with topical pediculicides such as permethrin 1% cream rinse or pyrethrin-based products, with nit removal using a fine-toothed comb. Reapplication in 7–10 days is usually required due to incomplete ovicidal activity. All household contacts should be examined, and infested individuals treated. Clothing, bedding, towels, and headgear should be washed and dried using hot cycles, and personal items such as combs and brushes disinfected.
Body lice management emphasizes hygiene, laundering clothing and bedding at high temperatures, and applying topical pediculicides when needed. Pubic lice are treated with topical pediculicides applied to affected hair-bearing areas, with simultaneous treatment of sexual contacts. Eyelash involvement is managed with petrolatum applied twice daily for several days. Second-line agents such as ivermectin or spinosad may be used for resistant cases.
Admission is rarely required and is reserved for patients with extensive bacterial superinfection or severe hypersensitivity reactions. Most patients can be discharged after treatment with appropriate education. Children may return to school after initial therapy, provided repeat treatment is completed. Follow-up is recommended to ensure eradication and to address social or safeguarding concerns when indicated.
Key points include confirming diagnosis by direct visualization, repeating treatment after 7–10 days, thorough environmental decontamination, and awareness of increasing resistance to first-line agents. Lindane is no longer recommended due to toxicity, and second-line treatments are effective but more costly.
Pediculosis is an infestation caused by lice that live in close association with humans. Bites are typically painless, and symptoms arise from the host’s inflammatory response to saliva and anticoagulants injected during feeding. Transmission occurs through direct contact and fomites such as combs, pillows, hats, and clothing. Head lice spread primarily through head-to-head contact and are more common in children and females. Pubic lice are usually transmitted through sexual contact. All lice are obligate human parasites and generally cannot survive away from a host for more than 7–10 days.
The condition is caused by three main species. *Pediculus capitis* (head lice) is the most common and affects all socioeconomic groups. *Pediculus corporis* (body lice) is associated with poor hygiene, poverty, and overcrowding, living primarily in clothing seams and transferring to the skin for feeding. *Phthirus pubis* (pubic or crab lice) typically infests coarse hair in the pubic region and is sexually transmitted. In children, pubic lice should raise concern for possible sexual abuse.
Clinical presentation varies by type. Head lice may cause scalp pruritus or be asymptomatic, often mistaken for dandruff. Body lice present with pruritus and excoriations, especially along clothing seams. Pubic lice cause intense itching, often worse at night. Physical examination focuses on identifying live lice or nits cemented to hair shafts, which cannot be easily brushed off. Empty nits alone do not confirm active infestation. Findings may include erythema, excoriations, secondary bacterial infection, posterior cervical lymphadenopathy, or bluish macules (maculae ceruleae) in pubic lice. Body lice are confirmed by finding nits in clothing seams rather than on the skin.
Diagnosis is clinical, based on careful history and physical examination with universal precautions. Laboratory testing is rarely necessary, although nits may be visualized under low-power microscopy and may fluoresce under a Wood lamp. Imaging has no role. Differential diagnoses include scabies, contact or allergic dermatitis, seborrheic dermatitis, and bed bug bites.
Management is primarily outpatient and supportive. Pruritus may be relieved with oral antihistamines or topical steroids. Head lice are treated with topical pediculicides such as permethrin 1% cream rinse or pyrethrin-based products, with nit removal using a fine-toothed comb. Reapplication in 7–10 days is usually required due to incomplete ovicidal activity. All household contacts should be examined, and infested individuals treated. Clothing, bedding, towels, and headgear should be washed and dried using hot cycles, and personal items such as combs and brushes disinfected.
Body lice management emphasizes hygiene, laundering clothing and bedding at high temperatures, and applying topical pediculicides when needed. Pubic lice are treated with topical pediculicides applied to affected hair-bearing areas, with simultaneous treatment of sexual contacts. Eyelash involvement is managed with petrolatum applied twice daily for several days. Second-line agents such as ivermectin or spinosad may be used for resistant cases.
Admission is rarely required and is reserved for patients with extensive bacterial superinfection or severe hypersensitivity reactions. Most patients can be discharged after treatment with appropriate education. Children may return to school after initial therapy, provided repeat treatment is completed. Follow-up is recommended to ensure eradication and to address social or safeguarding concerns when indicated.
Key points include confirming diagnosis by direct visualization, repeating treatment after 7–10 days, thorough environmental decontamination, and awareness of increasing resistance to first-line agents. Lindane is no longer recommended due to toxicity, and second-line treatments are effective but more costly.
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