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General - Parasitology πŸͺ± > L5: Myiasis > Flashcards

L5: Myiasis Flashcards

1
Q

What is the definition of Myiasis?

A

It is the invasion of the tissues of man or animals by larvae of dipterous (have 2 wings) flies.

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2
Q

What is Myiasis classified according to?

A
  • According to the habitat (site of invasion)

- According to the habit (biological habit of the fly)

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3
Q

What are the types of Myiasis according to the habitat?

A

Internal: intestinal and urogenital

External: cutaneous, ocular, nasopharyngeal, and aural

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4
Q

How does intestinal Myiasis occur?

A

Flies may deposit their eggs or larvae on human food or on the anus (particularly in children in rural areas) during sleep or defecation in open places.

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5
Q

What are the symptoms of intestinal myiasis?

A

Larvae find their way to the intestine and cause non-specific symptoms like nausea, vomiting, abdominal discomfort, or pain with diarrhea.

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6
Q

Where can we find larvae in case of intestinal myiasis?

A

Living and dead larvae appear in stools or vomitus

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7
Q

What are examples of larvae that cause intestinal myiasis?

A

larvae of Calliphora, Lucilia, Musca, and Fannia.

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8
Q

How does urogenital myiasis take place?

A

Larvae may enter through urinary or genital orifices or through lesions on orifices during urination in open places.

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9
Q

What are the symptoms of urogenital myiasis?

A

They may cause obstruction to the urine flow with dysuria or inflammation in the urinary passage with pus, mucus, and blood in the urine.

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10
Q

Where can we find the larvae in case of urogenital myiasis?

A

Larvae are passed in the urine.

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11
Q

What are examples of larvae that cause urogenital myiasis?

A

Fannia (the latrine fly) , Musca, Calliphora and Sarcophaga

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12
Q

How does cutenous myaisis take place?

A
  • This occurs when wounds or ulcers are invaded by larvae of the flies.
  • Sometimes, larvae may invade intact skin causing boil-like lesions.
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13
Q

What are the symptoms of cutaneous myiasis?

A

C/P: Sever pruritis, creeping eruption, or boil-like lesion may be presenting symptoms.

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14
Q

What are examples of larvae that can cause cutaneous myiasis?

A

Example: . Wohlfahrtia, Chrysomia ,Cordylobia and Dermatobia.

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15
Q

How do ocular or nasopharyngeal myiasis take place?

A

Larvae of some flies are attracted to the discharge coming from the eye or the nose, to find their way to the conjunctiva or the nose and may sometimes reach the brain.

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16
Q

What are the symptoms of ocular or nasopharyngeal myiasis?

A
  • Severe pain in the eye is the first complaint in ocular myiasis followed by lacrimation and conjunctival irritation.
  • c/p: Nasal myiasis presented with foul-smelling discharge followed by nasal obstruction, fascial oedema, frontal headache, and epistaxis.
17
Q

What are examples of larvae that can cause ocular or nasopharyngeal myaisis?

A

Calliphora, Sarcophaga, and Hypoderma

18
Q

How can aural myiasis take place?

A
  • Purulent exudates discharged from running ears attract some flies and they lay eggs or larvae there.
  • Larvae invade the middle ear, inner ear, or brain tissue in extreme cases.
19
Q

What are the symptoms of aural myiasis?

A

C/P: Patient complains of crawling sensation and buzzing noise and sometimes foul-smelling discharge or perforation of the drum occur.

20
Q

What are examples of larvae that can cause aural myiasis?

A

Cochliomyia, Wohlfahrtia, Sarcophaga, Lucilia and Chrysomia.

21
Q

What is myiasis classified into according to the biological habit of the fly?

A

Specific, Non-specific and accidental

22
Q

What is specific myiasis?

A

This is the condition when larvae invade only living tissues (Obligatory tissue parasites)

23
Q

What are examples of specific myiasis?

A
  • Hypoderma and Dermatobia: the larvae of which, invade the skin causing boil-like swellings
  • Wohlfahrtia and Oestrus: invade the eyes, nose, and external ears
24
Q

What are the sites of specific myiasis and its symptoms at each place?

A

 In the eye, they cause conjunctivitis and corneal ulcers.

 In the nose, obstruction and persistent bloody purulent discharge.

 In the ears, external otitis.

25
Q

What is the definition of semi-specific myiasis?

A

includes flies that habitually oviposit or larviposit on dead tissues of man or animals or decaying organic matter (Facultative parasites), However, they can be attracted by the offensive discharge coming from neglected wounds, or inflamed ears and eyes and thus deposit their larvae or eggs in such tissues.

26
Q

What does the presence of larva do in case of non-specific Myiasis?

A

The presence of larvae prevents healing and induces sepsis.

27
Q

What are examples of semi-specific myiasis?

A

Sarcophaga, Lucilia, Calliphora, Wohlfahrtia and Chrysomia.

28
Q

What is accidental myiasis?

A
  • When the fly eggs or larvae are deposited on food material (e.g. cheese and vegetables) and then they are accidentally ingested leading to intestinal myiasis.
  • Also, when the eggs are deposited around the anal canal or urogenital orifice, the larvae can travel up the passages leading to intestinal or urogenital myiasis, respectively.
29
Q

What are examples of larvae that cause accidental myiasis?

A

Biophilia in cheese, Drosophila in fruits, and Fannia (the latrine fly).

30
Q

How is myiasis diagnosed?

A

(1) Clinical picture according to the tissue invaded.

(2) By finding the larvae in the lesion.

31
Q

How are larvae identified?

A

Larvae are identified by their posterior spiracles or through their breeding to become adult

32
Q

What are the methods of treatment of myiasis?

A

1- Removal of the larvae:
 manual excision or endoscopy
 by using purgatives or douches
 following suffocation of larvae by Vaseline or petroleum oil

2- Treatment of secondary infection by antiseptics and antibiotics.

33
Q

What are the methods of prevention and control of myiasis?

A
  1. Insecticides and nets for the control of flies.
  2. Protection of food from flies by following strict hygienic measures.
  3. Cleaning and covering of wounds by gauze and wound dressing
34
Q

What is the benefit of larvae of flies?

A

(1) The flies’ larvae represent an important food source for many living organisms as birds and lizards.
(2) Some people in different cultures depend on these larvae as a food source rich in protein.
(3) Maggot therapy

35
Q

What is maggot therapy?

A

the medical usage of flies’ larvae):

οƒœ It is a type of old used traditional therapy involving the introduction of life, disinfected fly larvae into non-healing skin and soft tissue wounds of a human for the purpose of cleaning out the necrotic tissue within a wound (debridement) and disinfection and enhancing healing.

οƒœ Select a species that feeds almost exclusively on necrotic tissue

General - Parasitology πŸͺ± (5 decks)

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