Lice belong to the order Phthiraptera. Lice infestation is called pediculosis.
- Lice are wingless, small (0.4-10mm in length), sucking, with claws.
- One pair of five-segmented antennae is present.
- The head, thorax, and abdomen are all distinctly visible.
- Nits are eggs approximately 1mm in length, having operculum; head nits are deposited on hair shafts. Operculum may be present. Be aware that hair casts, dander, hair spray, and fungal infection can mimic nits (McPherson & Pincus, 2011). Body lice nits are deposited on clothing.
- Spread of lice occurs through close contact/shared clothing.
The three types of lice in humans: Head: Pediculus humanus capitis Body: Pediculus humanus corporis Pubic: Phthiris pubis |
- Head and body lice are longer than they are wide, approximately 3mm in length. Head and body are indistinguishable from each other to the nonspecialist.
- Pubic lice may measure up to 2mm in diameter. They are crab-like in appearance.
- "Crabs" may be passed from human to human during sexual or non-sexual transmission. Transmission occurs from close contact or sleeping on an infested bed or using infested towels.
- Note: Pubic lice found on children may be a sign of sexual abuse.
Lice species are animal-specific. Animals do not get lice from humans, nor do they spread lice from humans.
20. CDC. Image# 17328. "This 1975 photomicrograph, originally provided by Reed & Carnrick Pharmaceuticals, depicted an enlarged view of a louse egg, laid upon a hair shaft, by a female Pediculus humanus var. capitis, prior to any pharmaceutical treatment implementation." PHIL public domain. Created 1975. https://phil.cdc.gov/Details.aspx?pid=17328
