Why are lice harmful? - briefly
Lice feed on blood, causing itching, skin irritation, and secondary bacterial infections; heavy infestations can lead to anemia, especially in children. Their presence also facilitates the spread of pathogens such as Bartonella and Rickettsia species.
Why are lice harmful? - in detail
Lice infestations create direct physiological problems. Their bites penetrate the skin, causing localized inflammation, itching, and redness. Repeated scratching can break the epidermal barrier, allowing bacterial colonization such as Staphylococcus aureus or Streptococcus pyogenes, which may lead to impetigo or cellulitis.
The insects also serve as mechanical vectors for pathogens. Head lice (Pediculus humanus capitis) can transport viruses like the human papillomavirus and bacteria including Borrelia recurrentis, the agent of relapsing fever. Body lice (Pediculus humanus corporis) are known carriers of Rickettsia prowazekii, Bartonella quintana, and Coxiella burnetii, each responsible for serious systemic illnesses.
Nutritional loss occurs when large numbers of parasites feed on blood, potentially causing anemia, especially in children and individuals with limited iron reserves. Chronic blood loss may result in fatigue, reduced cognitive performance, and impaired growth.
Psychological effects arise from visible infestation and social stigma. Persistent awareness of infestation can increase stress levels, disrupt sleep, and diminish concentration, indirectly affecting academic or occupational productivity.
Summary of harmful consequences:
- Skin irritation, itching, and secondary bacterial infection
- Transmission of vector‑borne diseases (e.g., relapsing fever, trench fever, epidemic typhus)
- Blood loss leading to anemia and related systemic symptoms
- Elevated stress and reduced mental performance due to stigma and discomfort
Effective control measures—prompt removal, appropriate pediculicidal treatments, and hygiene practices—mitigate these risks and prevent outbreak escalation.