SCABIES - PowerPoint Presentation

Slide1

SCABIESSlide2

Causative organism: scabies mite

sarcoptes scabei

var

hominis

.

an obligate human parasite

Animal scabies

mites may result in transient symptoms in humans, but they are not a cause of persistent infestations.

T

ransmission

is via direct and prolonged contact with an infected individual. Slide3

Mites can

survive up to 3 days away from human skin, so fomites such as infested bedding or clothing are an alternate but infrequent source of transmission.

The entire life cycle of the mite lasts 30 days and is spent within the human epidermis. After copulation, the male mite dies and the female mite burrows into the superficial skin layers and lays a total of 60-90 eggs. Slide4

The ova require 10 days to progress through larval and nymph stages to become mature adult mites. Less than 10% of the eggs laid result in mature mites.

Mites move through the top layers of skin by secreting proteases that degrade the stratum

corneum. They feed on dissolved tissue but do not ingest blood. Scybala

(feces) are left behind as they travel through the epidermis.Slide5

Life cycle of sarcoptes

scabeiSlide6

Upon initial infestation, a delayed type IV hypersensitivity reaction

to the mites, eggs, or scybala develops over the ensuing 4-6 weeksPreviously sensitized individuals can develop symptoms within hours of

reexposure. Scabies occur primarily in institutional settings such as prisons and long-term care facilities such as nursing homes and hospitals. Natural disasters, war, and poverty lead to overcrowding and increased rates of transmission.Slide7

Complications

Complications of scabies are rare and generally result from vigorous

rubbing and scratching. Disruption of the skin barrier puts the patient at risk for secondary bacterial invasion, primarily by

Streptococcus

pyogenes

and

Staphylococcus

aureus

.

Superinfection

with

S

pyogenes

can precipitate acute

poststreptococcal

glomerulonephritis

and even

rheumatic fever

.

More common

pyodermas

include

impetigo and

cellulitis

,

which may rarely result in sepsis. Scabies infestations can exacerbate underlying eczema, psoriasis.Slide8

Manifestation

Lesion distribution differs in adults and children.

Adults manifest lesions primarily on the flexor aspects of the wrists,

the

interdigital

web spaces of the hands, the dorsal feet,

axillae

,

elbows, waist, buttocks, and

genitalia.

Pruritic

papules and vesicles on the scrotum and penis in men and

areolae

in women are highly characteristic.Slide9

2.Infants

and small children develop lesions predominantly on the

face, scalp,

neck,

palms, and soles,

although any site may be involved.

All

cutaneous

sites are susceptible in

immunocompromised

and elderly patients, who often have a history of a widespread,

pruritic

eczematous eruption.

Consider the diagnosis of scabies in any patient presenting with a recent onset of intense itching that is accentuated at night.Slide10

Burrows

are a pathognomonic sign and represent the intraepidermal tunnel created by the moving female mite. They appear as

serpiginous, grayish, threadlike elevations ranging from 2-10 millimeters long. They are not readily apparent and must be actively sought. A black dot may be seen at one end of the burrow, indicating the presence of a mite.

Locations for burrows

include the

webbed spaces of the fingers,

flexor surfaces of the wrists, elbows,

axillae

,

belt line, feet,

scrotum in men, and

areolae

in women. In infants, burrows are commonly located on the palms and soles.Slide11

Secondary lesions:

These are the result of scratching, secondary infection, and/or the host immune response against the mites and their products.

Characteristic findings include excoriations, widespread eczema, honey-colored crusting, postinflammatory hyperpigmentation,post

scabietic

nodules.Slide12

Norwegian scabies.

Crusted scabies, previously referred to as Norwegian scabies, manifests with marked thickening and crusting of the skin

. Lesions are often hyperkeratotic, crusted, and cover large areas. Marked scaling is common, and pruritus

may be minimal or absent. Nail dystrophy and scalp lesions may be prominent. Predominantly affected are those with

immunosuppression

, neurological disorders, or institutionalization.Slide13

Investigation

Skin scraping: Place a drop of mineral oil on a glass slide, touch a No. 15 blade or a 7-mm curette to the oil, and scrape infested skin sites, preferably primary lesions such as vesicles, papules, and burrows .The skin scrapings are placed on a glass slide, covered with a

coverslip, and examined under a light microscope Add 10% potassium hydroxide (KOH) to the skin scraping. This dissolves excess keratin and permits adequate microscopic examination.Slide14

Treatment includes administration of a

scabicidal

agent, an antipruritic agent such as a sedating antihistamine, and an appropriate

antimicrobial agent

if secondarily infected.

All family members and close contacts

must be evaluated and treated, even if they do not have symptoms

All carpets and furniture

should be vacuumed and vacuum bags immediately discarded.

Patients with crusted scabies or their caregivers should be instructed to

remove excess scale

to allow penetration of the topical

scabicidal

agent and decrease the burden of infestation. This can be achieved with warm water soaks followed by application of a

keratolytic

agent such as 5% salicylic acid .Slide15

Scabicidal drugs

Gamma benzene hexachloride,1% -1 applicationBenzyl benzoate25%-3 application for 12hrly interval

Lindane Malathion

Permethrin,5%-1 application of 12hr

Technique of application:

Apply the lotion or cream to the affected body surface from the neck down.

Leave the lotion for

12

hours .

And then wash off in shower.

If hands are washed out during this period then reapply the lotion or cream

A repeat of this after 1 week is

someimes

suggested .

Clothing and bedding is laundered.Slide16

Microscopic view of sarcoptes

Burrows over the wristSlide17

Burrow

Norwegian scabiesSlide18
Slide19

Pediculosis

Slide20

Also known as lice infestation.

Lice are flat ,wingless blood sucking insects.They lay eggs on hairs and

clothings .Two types of lice are responsible for the disease in human :pubic louse and body louse(scalp louse is the variant of body louse)Slide21

Infestation with head louse,

Pediculus humanus capitis

, is common and highly contagiousSlide22

Common among school

childrens and more common in those who live in unhygenic and or poor social conditions.

Mode of transmission is by head to head contact .pubic louse are transmitted through sexual contact. Can be transmitted by infested clothings or beddings.Slide23

Clinical presentation

Itching :usually starts from the sides and back of scalp .scrating result in excoriation and secondary bacterial infection

, cervical lymphadenopathyIf chronic infestation then

lichenification

and pigmentation can be seen .Slide24

The diagnosis is confirmed by identifying the living louse or nymph on the scalp or on a black sheet of paper after careful fine-toothed combing of wet hair that has had conditioner applied

. The empty egg cases ('nits') are easily seen along the hair

shaft. These are characteristically difficult to dislodge. Slide25
Slide26
Slide27

Nits Slide28

Treatment

Malathion/permethrin

Carbaryl lotion applied to scalp/whole body for 12 hors and then wash the hair and repeated in 7 days .Nits are removed with combs.

Clothing should be

cleaned with hot water or even insecticides in

s

ome cases

.

Sexual partners should also be treated.