Pediculosis

Definition

An infestation of lice (Phthiraptera: Anoplura), specifically members of the family Pediculidae, on a host animal. In humans, the condition is anatomically distinguished as pediculosis capitis (head lice), pediculosis corporis (body lice), or pediculosis pubis (pubic lice). The term properly denotes any louse infestation but is often used colloquially to mean head lice specifically. Pediculosis represents a significant ectoparasitic disease in medical and veterinary contexts, with transmission occurring primarily through direct host contact or shared fomites.

Etymology

From New Latin, derived from Latin pediculus 'louse' (diminutive of pedis 'louse') + -osis 'disease condition'

Example

Outbreaks of pediculosis capitis are common in elementary school settings where children engage in close head-to-head contact during play; inspection of the occipital scalp and behind the ears reveals nits cemented to hair shafts near the scalp surface.

Synonyms

• louse infestation
• phthiriasis

Related Terms

• Pediculidae
• Anoplura
• Phthiraptera
• pediculicide
• nit
• vector-borne disease
• Ectoparasite
• pediculosis capitis
• pediculosis corporis

Usage Notes

Specialists distinguish pediculosis by anatomical location (capitis/corporis/pubis) and louse species. The term should not be used for chewing lice (Mallophaga), which infest birds and mammals but belong to a different suborder. 'Pediculosis' without modifier is ambiguous—clinical and entomological writing prefers the specific form. Body lice (Pediculus humanus humanus) are competent vectors of Rickettsia prowazekii (epidemic typhus) and Borrelia recurrentis (louse-borne relapsing fever), making pediculosis corporis historically significant in disease ecology.