Pediculus humanus capitis ( head lice)

Pediculus humanus corporis (body

lice)

Phthirus pubis (pubic lice)

PEDICULOSIS AND PHTHIRIASIS

• Head lice are most commonly found in school children, with the most vulnerable age being 4-11 years old

• No significant sex differences• Do not discriminate rich or poor • Do not have any preference towards dirty

or clean

PEDICULOSIS

Pediculosis has a worldwide distributionIn epidemiologic school surveys in

different countries found to be :

15% in France (Combescot, 1990),

33.7% in Australia (Speare and Buettner, 1999),

40% in Taiwan (Fan et al., 1991)

28.3% in the U.K. (Downs et al., 2000)

USA : has risen steadily over the last 3 decades (Guenther, L, Medscape)

PREVALENCE

• Fam : Pediculidae,

ordo : Anoplura

Class : Insecta•Consist of head, thorax and abdomen•3 pair of legs, with claw (to cling to and crawl through human hair) •wingless

MORPHOLOGY

• A permanent ecto- parasite• blood-sucking insects • Die after 10 days starvation• Incomplete meta morphosis

LIFE CYCLE

Source : www.antiv.org

MORPHOLOGY AND HABITAT

P.humanus P.humanus capitiscapitis

P.humanus P.humanus corporiscorporis

Phthirus pubisPhthirus pubis

Live on Live on human hairhuman hair

clothing and clothing and beddingbedding

Pubic hair, eye Pubic hair, eye lash, moustache lash, moustache and beard and and beard and armpitarmpit

Difficult to differentiate: Difficult to differentiate: muscle of the thorax of muscle of the thorax of P. P. humanus corporishumanus corporis clearly clearly seenseen

Rounded body Rounded body (crab louse)(crab louse)

Phthirus pubis ( crab louse)

• Eggs : laid at the base of hairs, about ½ -inch from the scalp

• A female louse can lay as many as 5 - 6 eggs each day (50-100 eggs in its lifetime)

• Eggs hatch after 7-10 days. 

PATHOGENESIS & SYMPTOMS

SYMPTOMS

P.humanus P.humanus capitiscapitis

P.humanus P.humanus corporiscorporis

Phthirus Phthirus pubispubis

Asimptomatic, Asimptomatic, itching, itching, papules. papules. Scratching : Scratching : secondary secondary infectioninfection

- plica - plica palonicapalonica

Itching/ Itching/ pruritus pruritus

(play role as (play role as vector of vector of epidemic epidemic typhustyphus, trench fevertrench fever, louse borne louse borne relapsing relapsing fever)fever)

• Itching/ Itching/ pruritus pruritus

at pubic areaat pubic area• eggs on eye eggs on eye lash can disturb lash can disturb eye visioneye vision

Source: Logical Image (Skin sight)

PEDICULOSIS CORPORIS

Phthiriasis

•Evidence of eggs/nits, nymph or adults

•Favourite places : behind the ears / at the

nape of neck

•‘Detection combing’

DIAGNOSIS

Source: DermAtlas (www.stanford.edu)

Head lice :Combing and manual

TREATMENT

Insecticide :• Shampoo/ lotion / mousse of

permetrin 1%, benzen hexachloride, pyrethrioid based

•Can be repeated after 10-14 days•Cutting hair if needed

TREATMENT

• Pediculosis humanus corporis: change and wash clothing frequently

• Body lice : bedding should be fumigated• Pubic lice : as recommended for head lice

TREATMENT (CONT’D)

• Transferred from person to person through comb, mats, bedding

• Phthirus pubis : sexual activity• P.humanus corporis : mostly in cool

climate; poor personal hygiene

EPIDEMIOLOGY