pediculosis

Pediculosis Dr Adeel Mushtaq PGR MD Dermatology Dermatology Department PGMI/LGH Lahore :

Pediculosis Dr Adeel Mushtaq PGR MD Dermatology Dermatology Department PGMI/LGH Lahore

Introduction to Lice:

Introduction to Lice Order ---------- Phtiraptera Suborder ---------- Anoplura Three specie of Anoplura parasatize humans: Pediculosis Capitis (Head Louse) Pediculosis Humanus (Clothing or body Louse) Pthirus Pubis (Pubic or Crab Louse)

Morphology of Lice:

Morphology of Lice

Pediculosis Capitis:

Pediculosis Capitis Female (Adult ) Greyish white (3-4 mm long) 40 days life span Lays about 7 eggs daily can lay 50–150 ova during a 16-day lifetime Male (Adult) Slightly smaller

Slide 7:

Head lice Male (left) Female (right)

Pediculosis Capitis (Cont.):

Pediculosis Capitis ( Cont.) Eggs Oval, Flesh colored (1 mm long) Lid(operculum) capping the free end Empty egg case(nit) appears white Hatch in about 8 days Nymph reaches maturity in about 10 days Cemented to hair shaft of scalp

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Birth of a Head Louse

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Nits (Empty egg cases)

Pediculosis Humanus:

Pediculosis Humanus Similar in appearance and development to head louse Natural habitat ---------- Clothing close to the skin Visit skin to feed Seams are a favoured site for Oviposition Eggs cemented to clothing fibres Do not survive High temprature Washing and ironing of cloths Temperature change in environment

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Pediculus Humanus

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Pediculus Humanus Inhabitate seams of cloths

Pthirus Pubis:

Pthirus Pubis Squat body 2 nd and 3 rd pairs of legs carry heavy, pincer-like claws Light brown eggs cemented to hairs Colonize: Axillary hairs, eyebrows, eyelashes, beared hairs, scalp margins and hairs of trunk and limbs in addition to Pubic hairs. Active at night otherwise sedantary

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Pthirus Pubis (Crab Louse)

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Crab louse eggs attached to abdominal hair Crab louse clinging to hairs on the abdomen

Mechanism of feeding:

Mechanism of feeding Anoplura are Solenophages Haustellum everts Buccal teeth rotate outwards to cut skin Protractors puch stylets out through haustellum Stylets advance in the dermis to probe a vessel

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Scanning electron micrograph of a crab louse showing haustellum with buccal teeth

Slide 21:

Scanning electron micrograph of a crab louse showing (a) everted buccal teeth (b)the protruded stylet bundle (a) (b)

Head lice (Pediculosis capitis):

Head lice ( Pediculosis capitis ) Prevalence and epidemiology Common in children (3-11 years, girls>boys) Quite common in Indian sub-continent Transmission is by direct head-to-head contact Poor hygiene and overcrowding enhance spread Fomites are controversial for transmission

Head lice (Pediculosis capitis):

Head lice ( Pediculosis capitis ) Clinical Features Scalp pruritus Pruritic papular lesion on the nape of neck Secondary bacterial infection More common on the parietal and occipital regions Plica Polonica ; Confluent, purulent mass of matted hair

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Pediculosis capitis live infestation

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Pruritic papular lesion on the nape of neck Pediculosis capitis with Secondary bacterial infection

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Plica Polonica : Elongated broad mass of uncombable matted hair with extensive hair loss due to anagen effluvium.

Head lice (Pediculosis capitis):

Head lice ( Pediculosis capitis ) Examination Direct by naked eye or lens Wood lamp : Live nits fluoresce with a pearly fluorescence; dead nits do not Diagnosis Insect is isolated from comb instead of scalp Diagnosis is confirmed by microscopy

Head lice (Pediculosis capitis):

Head lice ( Pediculosis capitis ) Differential Diagnosis Scalp impetigo Peripilar keratin casts ( Pseudonits ; hair muffs) Dried globules of cheap hair lacquer Seborrhic scales White Piedra ( Trichosporon cutaneum ) Black piedra ( Piedraia hortae )

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White piedra

Treatment:

Treatment Fomite /Environmental Control Avoid contact with possibly contaminated items (hats, headsets, clothing, towels, combs, hair brushes, bedding, upholstery) Bedding, clothing, and head gear should be washed and dried on the hot cycle of a dryer Combs and brushes should be soaked in rubbing alcohol or Lysol 2% solution for 1 h

Treatment (Cont.):

Treatment ( Cont.) Chemical Pediculicides Lindane 1% Organochlorine Neurotoxic to insects (inhibit GABA) Known hypersensitivity Neurotoxic and carcinogen to humans Resistance developed

Treatment (Cont.):

Treatment ( Cont.) Malathion 0.5% Organophosphate Cure rate 33-75% Suitable for all ages and asthmatics Relatively safer in pregnancy and breast feeding Resistance developed Unpleasant smell, highly irritant

Treatment (Cont.):

Treatment ( Cont.) Carbaryl ( Carbaril ) Organophosphate Highly carcinogenic for humans Banned in many countries as a treatment of head lice

Treatment (Cont.):

Treatment ( Cont.) Pyrethrins 0.33% shampoo Naturally occurring organic insecticide In seed cases of perenniel plant Pyrethrum Synergized with Piperonyl Butoxide 4% May enhance symptoms of Asthma Carcinogenic for humans Highly inflammable

Treatment (Cont.):

Treatment ( Cont.) Synthetic Pyretheroids Permethrin 1% Drug of choice Cure rate up to 70%-87% Contact dermatitis and Pruritus (Formaldehyde) Safest for all ages, asthmatics, pregnant and breast feeders Phenothrin Less safer than permethrin Associated with hair loss

Treatment (Cont.):

Treatment ( Cont.) Dimeticone 4% lotion Silicon polymer, antifoaming agent Kills lice by blocking tracheae and disrupting water balance Suitable for all ages and asthmatics Cure rate up to 70% Odorless Mild skin irritation

Treatment (Cont.):

Treatment ( Cont.) Crotamiton 10% Relatively newer Acaricidal and Insecticidal Mechanism of action not known Cause skin irritation Often confused with crotamin Ivermectin 1% Applied for 10 minutes

Treatment (Cont.):

Treatment ( Cont.) General instruction for use of chemical pediculicide Apply topical on scalp over nightly Repeat treatment after 10 days Liquid/Lotion form preferable to shampoos Aqueous base solution is preferable to alcohol base

Treatment (Cont.):

Treatment ( Cont.) Oral Pediculicides Ivermectin 200 µg/kg Two doses at 10 days interval required Not in children weighing less than 15 Kg Co- Trimoxazole Kills symbiotic bacteria living within lice Use in combination for treatment resistant head lice

Treatment (Cont.):

Treatment ( Cont.) Physical Pediculicides Bug Buster wet combing Combing wet hairs with the fine-toothed Bug Buster comb Repeat after every 4days for 2 weeks Robi comb Battery powered device Combing dry hairs with electronic lice comb

Slide 42:

Bug Buster wet combing Licenders Comb

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Robi comb

Treatment (Cont.):

Treatment ( Cont.) Isopropyl myristate and cyclomethicone Remove the wax coating on the louse exoskeleton, leading to dehydration and subsequent death Cure rate 52%-82% Coconut, anise, and ylang ylang spray Block trachea and disrupt water balance Cure rate up to 82% Both physical insecticides should not be used in children less than 2 years, pregnant and breast feeders

Treatment (Cont.):

Treatment ( Cont.) Devices that deliver hot air to hairs and scalp Simple shaving the scalp hairs Plant derived essential oils Anecdotal evidence Lavender oil, tea tree oil and neem Head louse repellents Containing piperonal Plant-derived essential oils (citronella)

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Hairdryer-like device — the LouseBuster

Clothing/body lice (Pediculosis corporis):

Clothing/body lice ( Pediculosis corporis ) Prevalence and epidemiology Uncommon in developed countries Flourishes in overcrowded, unhygienic situations Vector of epidemic typhus ( Rickettsia prowazeki ) , trench fever ( Rochalimaea quintana ) and louse-borne relapsing fever ( Borrellia recurrentis )

Clothing/body lice (Pediculosis corporis):

Clothing/body lice ( Pediculosis corporis ) Clinical Features Pruritus (sensitization to louse salivary antigens) Asymptomatic Excoriations, secondary bacterial infection Hyperpigmentation (‘vagabonds’ disease’; morbus errorum )

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Pediculosis corporis eczematized lesions

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Pediculosis corporis Severely malnourished, ill-kept, homeless male with multiple excoriations, erosions and crusted papules, and nodules and eczematized lesions. Lice and nits are seen in the seams of clothing (inset)

Clothing/body lice (Pediculosis corporis):

Clothing/body lice ( Pediculosis corporis ) Differential Diagnosis Scabies Atopic dermatitis Allergic contact dermatitis Irritant contact dermatitis Drug reaction Viral exanthema Systemic causes of pruritus Renal impairment Hepatic impairment

Clothing/body lice (Pediculosis corporis):

Clothing/body lice ( Pediculosis corporis ) Treatment It is the clothing, not the patient, which needs treatment Tumble-drying High-temperature laundering of undergarments Dry cleaning of outer clothing Cloths treated with insecticides (for epidemics)

Crab lice (Phthiriasis pubis):

Crab lice ( Phthiriasis pubis) Prevalence and epidemiology Transmitted by close physical contact, usually sexual More in sexually active adults Associated with other STDs Only in children of effected parents Decline in females due to waxing of pubic hair

Crab lice (Phthiriasis pubis):

Crab lice ( Phthiriasis pubis) Clinical Features Itching, mainly in the evening and at night Underclothes may be spotted with altered blood Papular urticaria , especially peri -umbilical Maculae caeruleae (Blue–grey macules ) on thighs or trunk In children, only colonize the eyelashes and scalp Eyelash infestation: Serous crusts, edema of eyelids

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Pediculosis pubis : papular urticaria At this magnification only inflammatory papules (sites of crab lice bites), which are extremely pruritic, are seen on the abdomen and the inner aspects of the thighs

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Pediculosis Pubis (Crabs) Nits (on hair shafts) and lice (on the skin and hairs) are present

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Crab louse eggs on the eyelashes Crab lice (arrows) and nits on the upper eyelashes of a child; this was the only site of infestation

Slide 58:

Maculae caeruleae

Crab lice (Phthiriasis pubis):

Crab lice ( Phthiriasis pubis) Differential Diagnosis Scabies Contact dermatits Extensive excoriation White piedra ( Trichosporon cutaneum ) Trichomycosis pubis ( Corynebacterium tenuis ) Hair casts (remnants of the inner root sheath)

Crab lice (Phthiriasis pubis):

Crab lice ( Phthiriasis pubis) Treatment Malathion , pyrethrins with piperonyl butoxide , pyrethroids and carbaryl may be used topically Oral Ivermectin 200 µg/kg All sexual contacts should also be treated Aqueous-based preparations are preferable Treatment should be repeated after 7-10 days

Phthiriasis palpebrarum (Eyelash infection):

Phthiriasis palpebrarum (Eyelash infection) Treatment White soft paraffin twice daily for 2–3 weeks Argon laser phototherapy Cryotherapy Fluorescein in concentrations of 10–20% Yellow mercuric oxide and physostigmine ointment Mechanical removal of lice and eggs with fine forceps Epilation of the lashes with their attached eggs