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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/Parasite8/2/2019 Assgnment Module 8 -New
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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.