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Lecture 4:

Dr. Jabar Etaby

Introduction : Cutaneous larva

migrans(CLM),frequently termed

creeping eruption,is a parasitic skin

infection that is caused by the

filariform larvae of various animal

hookworm nematodes.

Distribution

CLM has a worldwide distribution

wherever have had skin contact with

soil contaminated with infected animal

feces. The disease most commonly

occurs in subtropical &tropical regions,

but may also occur in temperate

climates particularly during the

summer months &during rainy

seasons.

Caustive agents

Ancylostoma braziliense

ahookworm of wild &domestic dogs

&cats is the

most commonly identified etiolgic

agent of CLM

Cutaneous (dermal) larval migrants

There are several examples of parasites that are

normally found in pets but can be transmitted to

humans.

For example, acommon tapeworm of

dogs,

Dipylidium caninum

, can be

transmitted to humans.

Immature forms of the common

roundworm of dogs,

Toxocara

canis

can also be found in humans,

causing a disease known as

visceral

larval migrans

Immature forms of both cat and

dog hookworms can also infect

humans, and this results in a

disease called cutaneous or dermal

larval migrants (CLM or DLM).

The eggs of dog and cat

hookworms hatch after being

passed in the host's feces, and the

next host is infected when these

larvae penetrate the host's skin.

Unfortunately, these larvae can not

tell the skin of one animal from

another, so they will penetrate

human skin if they come in contact

with it.

However, a human is an unnatural

host, so the larvae do not enter the

blood stream as they would in a

dog or cat.

Rather, they remain in the skin for

extended periods of time (weeks or

months in some instances) and

finally die.

Disease Signs&Symptoms:

The most common portals of entry

by the larvae are the exposed areas

of the body such as the dorsum of

the feet, lower legs, arms and hands,

thighs and abdomen also may be

involved probably due to lying

directly on contaminated sand.

2-Visceral larval migrants(VLM)

larvae of specific or non specific

host migrates by after skin

pentration or directly to the gut

then hatching there ,then it will be

gone to the viscera, liver, lung,

muscles or even brain e.g A.

lumbericoides ,T. cains. T. cati &

Ascaris. equi

So, there be irritation &

eosinophila(5%or some times even

70% or 80%) but still it is not

diagnostic features as we knew .

Weather it is CLM or VLM there is

some sort of attraction to words the

anterior part of the body (by

migration through blood vessels or

lymph vessels

This migrate be due to the presence

of high tension of O2 in the anterior

part of the body espically in the

viscera

Note:

T. canis cause kid blindness &painfultumor.

Toxocara spp. Cause infection of the CNS

during the 1

day of infection, the eggs in

the gut will hatch into larvae so the curve is

high then it will decline with migration of

the larvae to other tissues & organs. So

liver from 1

day of infection they start to

increase gradually till the 1

week then

decline

Lung :

the decrease in the liver will

syncronise with increase in the

lung due to migration of the larvae

from the liver to the lung .

Brain may be from the beginning of inf.

the larvae reach the brain directly by

remaining only for some times in the

lung then migrate & stay in the brain

because the brain tissue is soft

&represents enriched media for the

parasite which remain

Not encysted as thy are away from

the immune response &it will

increase during the 3

week& at

the same time decrease in lung

&liver .

The infective stage in CLM is 3

stage larvae while in VLM is 2

stage larvae

As the larvae migrate through the skin and

finally die, there is an inflammatory response,

and the progress of the larvae through the skin

can actually be followed since they leave a

tortuous "track" of inflammed tissue just under

the surface of the skin

Treatment of such infections requires surgical

removal of the migrating larvae. Considering the

location of larvae, just under the skin, in light

infections this can be done under local anesthesia

and is a relatively simple procedure.

Infections involving large numbers

of larvae can be very

uncomfortable, and treatment

(removal) might require general

anesthesia and supportive

treatment with anti-inflammatory

drugs.

How do humans come in contact

with the larvae of dog and cat

hookworms? A common source of

infection in developed countries is

probably sandboxes.

If you have a sandbox in your

backyard, it is almost certain that

cats in the neighborhood are using it

as a large litter box.

Moreover, the sand provides a

nearly ideal environment for the

hookworm eggs to develop and

hatch and for the larvae to survive.

Diagnosis:

dignosis of CLM is based on a

history of exposure and clinical

appearance of the skin eruption.

Allergic dermatitis, secondary

bacterial infection

Peripheral eosinophilia and increase

IgElevels are found in a minority of

patients. Skin biopsies are usually

not effective at establishing the

diagnosis.

Histologic examination

may lead to edge of the track may

contain a larva trapped in follcular

canal, stratum cornea or dermis.

CLM of the foot.

(Original image from:

Companion Animal Surgery

.")

CLM of the foot.

Thus, keeping sandboxes covered

to prevent cats from defecating in

them is a worthwhile "ounce of

prevention."

CLM (Original image from and copyrighted by

Dermatology Internet Service,

Department of Dermatology, University of

Erlangen

(Original image from and

copyrighted by

Dermatologic

Image Database, Department of

Dermatology, University of Iowa

College of Medicine

Other places where cats might

defecate are also possible sources

of infection, including flower beds

and vegetable

Garden Dogs are much less

fastidious about where they

defecate, so it is more difficult to

control dog feces as a possible

source of infection

If you own a dog two measures that

you should take are (1) keep you

dog free of hookworms and(2)

make sure that you clean up the

dog's feces on a regular basis

Also, if you "walk" your dog in a

park or playground, and in

particular in my front yard, make

sure that you pick up and dispose

of any fecal material the dog might

leave behind