What can lice transmit? - briefly
Body lice serve as vectors for bacterial illnesses such as epidemic typhus, trench fever, and relapsing fever, while head lice are not recognized as significant disease transmitters. Consequently, the public health risk is confined mainly to infestations of the body‑dwelling species.
What can lice transmit? - in detail
Lice are obligate ectoparasites that can act as vectors for several bacterial agents. Body lice (Pediculus humanus humanus) are the only species with confirmed disease transmission. They acquire pathogens while feeding on infected blood and excrete contaminated feces, which enter the host through skin abrasions.
- Rickettsia prowazekii – causes epidemic (louse‑borne) typhus; incubation 6–14 days; symptoms include fever, rash, and severe headache; mortality rises without treatment.
- Borrelia recurrentis – responsible for louse‑borne relapsing fever; characterized by recurring episodes of high fever, headache, and myalgia; rapid diagnosis and antibiotics are essential.
- Bartonella quintana – agent of trench fever; presents with prolonged fever, severe leg pain, and occasional rash; transmitted when contaminated lice feces are scratched into the skin.
Head lice (Pediculus humanus capitis) have not been linked to systemic infections. Their impact is limited to pruritus, secondary bacterial skin infection (typically Staphylococcus aureus or Streptococcus pyogenes), and psychosocial distress. Pubic lice (Pthirus pubis) can facilitate the spread of sexually transmitted bacteria such as Treponema pallidum (syphilis) and Haemophilus ducreyi (chancroid) through micro‑abrasions, although documented cases are rare.
Transmission dynamics differ among species. Body lice thrive in unhygienic conditions, spreading rapidly in crowded settings like refugee camps, prisons, and homeless shelters. Control relies on regular laundering of clothing at temperatures ≥ 60 °C, use of insecticidal powders, and prompt treatment of infected individuals with oral antibiotics (e.g., doxycycline for typhus).
In summary, only the body form of the human louse is a proven vector for serious bacterial diseases, while the head and pubic varieties pose mainly local irritation and occasional secondary bacterial risk. Effective hygiene and targeted antimicrobial therapy remain the primary preventive measures.