What diseases do lice cause? - briefly
Body lice transmit epidemic typhus, trench fever, and relapsing fever. Head lice are not associated with systemic disease, though they can cause itching and secondary bacterial skin infection.
What diseases do lice cause? - in detail
Lice are vectors for several bacterial infections that affect humans. The most medically significant species is the body louse, which transmits three distinct pathogens.
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Epidemic typhus – caused by Rickettsia prowazekii. Infection follows the bite of an infected louse or contact with contaminated feces. Symptoms include high fever, severe headache, rash that begins on the trunk and spreads outward, and potentially fatal complications such as pneumonia or encephalitis if untreated. Antibiotic therapy with doxycycline is the standard treatment.
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Trench fever – caused by Bartonella quintana. The disease presents with recurrent fevers, severe leg pain, and headache. It is associated with crowded, unhygienic conditions, historically among soldiers in World War I. Doxycycline or azithromycin are effective; the illness is usually self‑limiting but may become chronic.
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Louse‑borne relapsing fever – caused by Borrelia recurrentis. Patients experience alternating episodes of high fever, chills, and malaise, each lasting several days and separated by afebrile intervals. Neurological involvement and severe anemia can occur. Prompt treatment with penicillin or doxycycline reduces mortality.
Head lice (Pediculus humanus capitis) rarely serve as disease carriers. Their primary impact is intense pruritus, which can lead to excoriation and secondary bacterial infection by Staphylococcus or Streptococcus species. Crab lice (Pthirus pubis) produce similar irritation in the pubic region and may also facilitate bacterial superinfection.
Transmission of louse‑borne pathogens requires close contact with infested clothing or skin, especially in situations where hygiene is compromised. Control measures focus on thorough laundering of garments at high temperatures, regular body hygiene, and the use of topical pediculicides (e.g., permethrin 1 % or ivermectin) to eliminate the insects. Early recognition of the associated infections and appropriate antibiotic therapy are essential to prevent severe outcomes.