How are lice transferred? - briefly
Lice spread mainly through direct head‑to‑head contact, which transfers live insects and their eggs. Secondary transmission occurs when contaminated items such as hats, combs, or hair accessories are shared.
How are lice transferred? - in detail
Lice spread primarily through physical contact and, to a lesser extent, via contaminated objects. Head‑to‑head interaction provides the most efficient route because adult females and nymphs cling to hair shafts and move readily when two persons touch heads. Even brief contact, such as hugging, sharing a pillow, or leaning together, can transfer several insects.
Secondary pathways involve personal items that come into direct contact with hair. Items include:
- Combs, brushes, hats, scarves, and hair accessories.
- Bedding, pillowcases, and towels that have been used within a few days.
- Clothing with attached hair, such as caps or uniforms.
Lice survive off the host for limited periods, typically 24–48 hours, depending on temperature and humidity. Warm, moist environments prolong viability, allowing insects to remain infectious on fabrics or surfaces for up to two days. Dry, cool conditions reduce survival time to less than twelve hours.
Transmission is most common among children in close‑quarter settings such as schools, daycare centers, and camps. High density of hair contact and shared belongings increase risk. Adults experience lower rates, primarily through contact with infested children or through occupational exposure in healthcare or childcare environments.
Preventive actions focus on minimizing direct contact and controlling shared items. Regular inspection of hair, especially after outbreaks, helps early detection. Washing potentially contaminated objects in hot water (≥ 50 °C) or using a dryer on high heat eliminates residual insects. Isolating personal items for at least 48 hours, when washing is impractical, reduces the chance of re‑infestation.