Where do lice appear in general? - briefly
Lice infest the hair, feathers, or fur of warm‑blooded hosts, most commonly humans, other mammals, and birds. They proliferate where close bodily contact and warmth provide suitable conditions for their life cycle.
Where do lice appear in general? - in detail
Lice are obligate ectoparasites that colonize specific host surfaces under conditions that support their life cycle.
The most common species affecting humans include:
- Head‑lice (Pediculus humanus capitis) – inhabit the scalp, attaching to hair shafts near the nape, behind the ears, and at the hairline. Eggs (nits) are cemented to the shaft within a few centimeters of the scalp, where temperature and humidity are optimal for development.
- Body‑lice (Pediculus humanus humanus) – reside in the seams of clothing, particularly in garments that remain close to the skin. Nymphs and adults move to the body to feed, but the primary habitat is the fabric.
- Pubic‑lice (Pthirus pubis) – prefer coarse hair in the genital region, perianal area, and occasionally chest or facial hair. The environment is typically warm and moist, facilitating reproduction.
Beyond humans, several lice species target animals:
- Dog and cat lice (Trichodectes canis, Felicola subrostratus) – occupy the fur, especially around the neck, tail, and ventral surfaces.
- Bird lice (various Mallophaga) – inhabit feathers and skin of wild and domestic birds, concentrating on the wing and tail feathers where grooming is limited.
Environmental reservoirs include:
- Clothing, bedding, and upholstered furniture – provide shelter for body‑lice eggs and nymphs when hosts are absent.
- Nest material of birds and mammals – accumulates lice stages that persist until new hosts occupy the nest.
Transmission occurs through direct contact with infested hair, skin, or clothing, and indirectly via contaminated items that retain viable stages for days to weeks, depending on temperature and humidity. Maintaining low humidity, regular laundering of textiles at high temperatures, and prompt removal of eggs from hair or fur reduce infestation risk.