assgnment module 8 -new

8/2/2019 Assgnment Module 8 -New

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CUTANEOUS MYIASIS


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DEFINITION OF

CUTANEOUS

MYIASIS


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Myiasis is a general term for pathologicalinfection by parasiticfly larvae feeding on

the host's living tissue.

Myiasis is infestation by the larvae

(maggots) of fly species within thearthropod order Diptera (two-wingedadult flies).
http://en.wikipedia.org/wiki/Parasitehttp://en.wikipedia.org/wiki/Flyhttp://en.wikipedia.org/wiki/Host_(biology)http://en.wikipedia.org/wiki/Biological_tissuehttp://en.wikipedia.org/wiki/Biological_tissuehttp://en.wikipedia.org/wiki/Host_(biology)http://en.wikipedia.org/wiki/Flyhttp://en.wikipedia.org/wiki/Parasite


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The larvae feed on the host's dead or

living tissue, body substances, oringested food.


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Myasis can be classified according to :

I. Site of tissue invaded

II. Biological habits of the larvae


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External myasis

1. Cutaneous

2. Ocular and nasopharyngeal

3. Aural

Internal myasis

1. Gastric myasis

2. Intestinal myasis

3. Urogenital myasis


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Obligatory Acquired living host for developmental changes and growth

Facultative Can grow with or without living in the host cell

Accidental Usually this happens when the host unknowingly ingested food

or drinks contaminated with the egg of higher diptera


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Female lays egg ontocarrier insect

Ex: mosquito

Human direct contactor during bite from the

carrier.

Once the egghatch,the larvae

burrow into the hostskin, produce small red

papule

The papule becomea fruncular like

(boil- like)


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Bacterial superinfection

Tetanus

Fatal cerebral myasis in infant due toinfestation the skin covering frontanelles


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Found in tropical Africa.

Lay their eggs on object contaminated with

urine or feaces,such as sandy soil or damp

clothing laid dry on the ground.


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Prickle heat sensation to severe pain

Agitation and insomniaFirst 2 days

Furuncular lesions with surrounding

inflammation6 days later

Tail end of larvae may be seen in

central pore.

Multiple infestation may

develop:enlarge lymph node and fever.

Late stages


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Infestation occur in young age because the

larvae are unable to penetrate adult skin.

Most active in shaded area, during late

afternoon hours

Most occur during months of June to

September


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A specific myiasis.

Larva burrows and wanders under the

skin.

More difficult to diagnose.

Causing flies:

-Gasterophilus spp

-Hypoderma spp

-first instar larva of Cuterebra spp(invade the human skin directly - mostprobably where laceration occurred)


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Characteristic Rash

Extreme itching

Starts as red bumps or blisters

-Wiggly tracks that lengthen

- Lesion typically begin on exposed skinpart


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Gasterophilus Intestinalis


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Causes superficial myiasis

Intense itching

Raised, red, linear serpentine lesion that advances atone end and fades at the other end

Characteristic lesion

Can extend up to 30 cm per day

May continue for several months

Lengthen of lesion

Spontaneously, either with or without suppuration

Ending of infestation


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Cause deeper (subcutaneous), more painful eruption

Can also cause fever, muscle pain, joint pain, scrotal swelling,ascites, fluid around heart, discontinuous and transient skinswelling, and invasion of brain and spinal cord

They release enzymes to break down tissue and easetheir movement

Tissue travelled by them becomes greenish-yellow

Usually cause mild disease


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Infestation of a surface wound or other openlesion b fly larvae of higher diptera

3 Major speciesof obligate parasites

encountered: New World ScrewwormOld World Screwworm

Wohlfahrts wound myiasis

9 Genera belonging families of Calliphoridae

Sarcophagidae

Muscidae


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1)Cochliomyiaspecies:

2 species of New

World genusCochliomyia:a)CochliomyiaHominivorax

b)Cochliomyia

Macellaria

2)Phormia andprotophormia

species

-Important species:Phormia Regina

more northernProtophormia

terraenova


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LuciliaCuprina

Lucilia Seracita-healing of deep

wound inhumans


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Blue bottle

Attracted forovipositionto any

decayingspecies.

2 important

species:Calliphora

Vicina

CalliphoraVomitoria


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Chrysomya Bezziana (obligateparasite in wounds) :depositing

150-500 eggs at site of wound orbody orifices


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SARCOPHAGIDAE

(Flesh Fly)

~ obligate parasite of warm blooded vertebrae

~ 2 genera sarchophaga sensu lata/wolfahrtria

~ females are larviparous deposite 1st instar

rather than eggs

~ ex : wohlfahrtria nuba feed on dead tissue rather thanlive tissue.

: wohlfahrtria vigil and wohlfahrtria opaca :

-penetrate host skin individually producing furuncle


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LIFE CYCLE :

occurs when wounds or ulcers areinvaded by larvae of flies which will

lay their egg in decaying flash

accidentally deposit their egg or larvae inneglected sores or wound.

Larvae damage the underlying tissue

by burrowing in it.The head of this larvae is in the tissuewhile the back region is visualized as asmall dot (breathing pores)

larvae feeds wound, size increase ;tissue destruction

Reach maturity in 5 days fall to theground which they burrow and pupate


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SUMMARY :


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Clinical synopsis

A 4-year-old girl, who had just arrived fromBolivia, was referred to EmergencyDepartment, as a result of furunculouslesions on the scalp.

The nodules had appeared 7 days before

and the area was itchy and painful


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Physical examination revealed a largeinflammatory, nodular plaque that

occupied the whole vertex of the scalp. There were several pores, each about 1

centimeter in diameter, from which exuded

serosanguineous discharge. A great number of living larvae were

observed (Fig. 1).

Moreover, the child was febrile andexhibited regional lymphadenopathy.Complete blood count showed

eosinophilia.


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Figure 1 : a great number of living

larvae were observed


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An occlusive dressing with paraffin oil for

24 hours is applied. After the occlusive dressing is removed,

the hair is cut, and the wounds are

cleaned, the furunculous nodules wereopened and the larvae extracted carefully(Fig. 2A).


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Figure 2A : the furunculous noduleswere opened and the larvae were

extracted carefully


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Partial approximation of the wound was

performed by a pediatric surgeon, but thecenter closed by secondary intention.

Microbiology analysis confirmed the

diagnosis of myiasis and identified thelarvae (Dermatobia hominis), and thesubspecies (Cochliomyia hominivorax)

(Fig 2B)


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Figure 2B : Cochliomyiahominivorax


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Larvae of Cochliomyia

hominivorax


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The diagnosis is made based on :

- the clinical appearance of the lesions andassociated symptoms.

-travel history of the patient.

Symptoms vary among the different agents ofcutaneous myiasis.


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One or more nonhealing boil-like lesions with erythema.

local symptoms of pain,

tenderness, or pruritis. Ultrasonographic images.

A small, white, worm-like

organism protruding from thelesion when pressedlaterally.


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the fly larvae may not be seen if no exit orbreathing hole is yet present.

Gasterophilus spp. present superficial andpresent clear, linear serpentine darktunnels (creeping eruption).


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The presents of maggots in the pre-existing wound larvae feeds the wound, their size will

increase and will cause tissuedestruction.


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FURUNCULAR MYIASIS

WOUND MYIASIS

MIGRATORY MYIASIS


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Digital pressure on both side of the lesions.

Block the skin opening by petroleum jelly, nailpolish, bacon or paste of tobacco.

Surgical incision

Drug : Ivermectin


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Irrigate the areawith saline or dilute

antimicrobial.

Removed manuallyor surgery (deep)


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Removed usingneedle for young

larvae ofGasterophilus spp.

Thiabendazole

Ivermectin


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1 ) eliminating or eradication the possiblesources of infection.

Any region that is warm and humid is ideal

for the breeding of Myiasis flies.

Such places must be destroyed by usinginsecticides and disposing waste materials

in the proper manner.


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A id l i td


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Avoidance sleeping outdoorsespecially babies in area infested by

Wolfahtria.

Protection and washing of food stuff to

prevent the accidental ingestion oflarvae.

Using of nets, screens and repellants.

Additi ll d l h i


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Additionally, good personal hygiene,proper sanitation, and correct hand

washing techniques are alsoimportant practices to be observed.

assgnment module 8 -new

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