Parasite
Pediculus (lice)
Blood-feeding lice; body louse is a disease vector
peh-DIK-yoo-lus
High-yield clue
Nits (eggs) cemented to hair shafts point to head lice, while the body louse is the classic vector for epidemic typhus and relapsing fever.
Overview
Wingless blood-feeding insect ectoparasites; the head louse (P. h. capitis) and body louse (P. h. corporis) are core exam organisms, with the body louse notable as a disease vector. It matters as the classic louse infestation and vector example.
Classification
- Arthropod ectoparasite
- Insect (louse)
- Obligate blood feeder
- Head vs body forms of P. humanus (the pubic louse is Pthirus pubis, a different genus)
Lab & identification clues
- Nits cemented to hair shaft vocabulary
- Adult louse on visual/microscopic exam
- Body louse lives/lays eggs in clothing seams
- Wet-combing detection concept
Associations
- Direct contact / shared items transmission
- Body louse vector: epidemic typhus, trench fever, relapsing fever
- Crowding/poor-hygiene epidemiology framing
- Pubic louse ('crabs') is Pthirus pubis, a separate genus with a sexual-contact study link
Commonly confused with
- Sarcoptes scabiei
- Hair casts / dandruff
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.