5. Ectoparasites

7/27/2019 5. Ectoparasites

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ECTOPARASITESParasitology Department

Medical Faculty of USU



Ectoparasites

General

Definition:

parasites which live on the surface of a

host and are dependent on at least one

gene or its product from that host to

complete their own life cycle

(Dr.Clive Bennet 1998)

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Ectoparasites

General

Ectoparasite infestations are often seen in

pediatric patients

Typical infestations result from arthropods

such as: Mites, Lice, Bugs, and Flea

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Mites

There are some arthropoda belonging to

order Arcarina such as, Itch mites(Sarcoptes scabies), and harvest mites/ red

bug mites (Trombiculidae).

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Itch Mites(Sarcoptes Scabies)

features

Adult female: ± 0.4mm long

It burrows into stratum corneum layer of skin

Eggs: laid in burrows, glossy, white andsmooth, lays2-3 eggs/day; hatch in 3-4 days

Larvae grise to skin surface and mature in14 to 17 days.

Adult females: life span 30 days

Adult male: dies shortly after mating

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Scabies

life cycle6



Scabies

features

Gravid female scabies mite

Burrow of Sarcoptes

consisting adult female

and eggs

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Scabies

Epidemiology

Transmissions:

Close contact such

as; holding hands,

sharing towel, clothingor bedding

Personal contact:

sleeping together,sexual

Breeding environments:

In overcrowded living

conditions

Elderly nursing homes

In school children

playing together

Roommates Sexual patrners

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Human scabies

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Scabies

Prevention

Avoid sharing personal stuff

Check family members

Clothing and underwear should changed

regularly

Have regular bathing

Keep all bedding well laundered

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Harvest Mites (Red bug mites)/

Trombiculidae

General

Infected stage is the

larvae as known

chiggers

Chiggers attach theskin of a host and

bite, causing a wheal

of intense itching and

severe dermatitis.

Some species are

vectors of the

rickettsiae that

causes scrub typhus.

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Lice

Features

Ordo pthiraptera;subordo: anoplura

Dorso-ventrally

flattened bodies

wingless Permanent

ectoparasites of mammals: sucking

blood Nocturnal feeding

Those parasitic tohumans are: bodylouse, head louse and

pubic louse

Lice live on the bloodof a host, obtained bypiercing the skin andsucking the bloodthrough their mouthparts.

The area bittenbecomes itchy andinflammed, and ofteninfected fromscratching

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Body Louse

General

Due to: Pediculushumanus corporis

Body lice are found

on the body andclothing or beddingused by infestedpeople. Occasionally

eggs are attached tobody hair

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Body Louse

Adult female louse her can lay up to 150 eggs aday during 20-day adultlife span.

Eggs hatch in 7-10 days,and the larvae matureinto adults in 9 days

Lives and lays eggs inthe seams (layers) of clothing

The adult louse emergesfrom clothing to take ablood meal, usually atnight.

Lives and lays eggs

in the seams

(layers) of clothing

The adult louse

emerges from

clothing to take ablood meal, usually

at night

General Epidemiology

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Body Louse

Medical important

Dermatitis

Vector of diseases:

o Trench Fever:

o Louse borne

epidemic typhus

o Louse borne

relapsing fever

Transmission:

o Fecal

contamination

o Body crushingo Physical contact

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Body Louse

Prevention and control

Personal hygiene

Changing and washing the clothing in water

hotter than 60ºC, preferably followed byironing

Permethrin in lotion, shampoo, emulsion, and

powder

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Head Louse

General

Due to: Pediculus humanus capitis

Definition: parasitic insectsm found on the

heads of people

Commonly found on the scalp, behind the ears

and near the neckline at the back of the neck.

Children 3-10 years are commonly affected

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Head Louse

General

The adult female louse

lays 7 to 10 eggs daily in

egg casings (nits) that

are cemented to the baseof hair shafts

Eggs hatch in 8 to 10

days, mature in 8 to 15

days, and live 9 to 30

days as adult

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Head Louse

epidemiology

Transmission: head to head contact iscommon during play at school and at home;

Wearing clothing, such as hat, scarves, coats etc

Using infested combs, brushes, or towels Lying on a bed, couch, pillow, carpet that has

recently been in contact with an infested person

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Head Louse

Medical important

o Itchy

o Erythema

o Discomforto Secondary infection:

o Vagabond’d disease: darkened, thickened

skin (hyperceratination)o Plica polonica: exudate, fungus grow, a fetid

odor

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Head Louse

Prevention and control

o Personal hygiene

o Regularly washing with soap and

warm water o Regularly combing with ordinary

comb

o Permethrin in lotion, shampoo, emulsion, andpowder

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Pubic louse

Due to: Pthirus pubis

Dwells primarily:pubic region

But it also be foundin armpits and rarelyin beards,mustaches,

eyebrows andeyelashes

Medical important:intense pruritis

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Bugs/ Cimex lectularus

General

It belongs to ordoHemiptera

Wingless

Reddish brown Nocturnal feeders

Thermal sensitive, thermaldeath point is 44-45ºC

After blood meal (10-15mins) retreats to itshiding place

Able to suffer long fasts

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Bugs/ Cimex lectularus

Epidemiology

Can live without any food

for over a year

Migrate from empty house

for inhabited area Active in warm climate and

hibernate in cold weather

Public transportations and

public gathering places arecommon avenues for the

dissemination of bed bugs

Carried easily in clothing,

traveling bags, suitcases,

and laundry

The bite itself is notpainful but erythema and

itching develop later

(swelling and irritation)

No convincing evidencethat it is a vector of any

human or animal

pathogen

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Wings are absent

Flattened laterally

Three pairs of legs for

jumping (specialized)

Varying in color from light to

dark brown

Both sexes of fleas takeblood-meals

Immature stages are free

living

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After taking blood-meals, females fertilized,

burrows into the skin where it is soft.

(such as: toes, foot, soft skin around thegenital region)

People habitually sitting on the ground

(children); the buttock may often be

infected

On the biting site will be very itchy and

inflamed, secondary infections (ulcer &

pus)

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FLEAS

EPIDEMIOLOGY

• Transmitter of

bubonic plague:

caused by Yersinia

pestis ( Disease of rodents; human

secondarily

infected). Mostimportant species:Xenopsylla cheopis .

Transmitter of

Typhus: Murine

Typhus or flea-

borne typhus.Caused by

Rickettsia mooseri .

Infection fromfeces/crushed

bodies of infected

fleas

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FLEAS

Medical important

section female tunga

PENETRATES THE SKIN

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THANK

YOU !

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5. Ectoparasites

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