أسئلة ريتين الخامسة بارا دمياط (قبل التعديل)
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Questions and Answers

What are the common symptoms associated with Oestrus larvae infestation in the eye?

Conjunctivitis and corneal ulcers are common symptoms.

Which flies are known to cause intestinal or urogenital myiasis by depositing their larvae in specific orifices?

Oestrus larvae are known to cause intestinal or urogenital myiasis.

How do Piophila larvae contribute to the production of 'casu marzu' cheese?

Piophila larvae are intentionally introduced into pecorino cheese to create the uniquely fermented texture and flavor.

What is the significance of the posterior spiracles in identifying larval species?

<p>The posterior spiracles help in accurately identifying the species of the larvae present.</p> Signup and view all the answers

What is the primary method of treating secondary infections caused by myiasis?

<p>Antiseptics and antibiotics are used to treat secondary infections.</p> Signup and view all the answers

What preventative measures can be taken to control fly infestations that lead to myiasis?

<p>Using insecticides, nets, and protecting food from flies are effective preventative measures.</p> Signup and view all the answers

What clinical sign would indicate a case of accidental cutaneous myiasis?

<p>The presence of larvae in an open wound with offensive discharge indicates accidental cutaneous myiasis.</p> Signup and view all the answers

Why might there be a need for excision or endoscopy in treating myiasis?

<p>Excision or endoscopy may be necessary to physically remove the larvae from affected tissues.</p> Signup and view all the answers

What are the common sites where fly larvae can enter the human body?

<p>Fly larvae can enter through urinary or genital orifices, the anus, or through lesions on the skin.</p> Signup and view all the answers

What symptoms may indicate the presence of fly larvae in the intestine?

<p>Symptoms include nausea, vomiting, abdominal discomfort, diarrhea, and potential obstruction of urine flow.</p> Signup and view all the answers

How do fly larvae cause ocular myiasis?

<p>Fly larvae enter the eye, leading to severe pain, lacrimation, and conjunctival irritation.</p> Signup and view all the answers

What health risks are associated with larvae invading the middle or inner ear?

<p>These invasions can lead to serious complications, potentially affecting brain tissue in extreme cases.</p> Signup and view all the answers

What distinguishes obligatory tissue parasites from other types of parasites?

<p>Obligatory tissue parasites invade only living tissues, as opposed to those that can affect dead tissues.</p> Signup and view all the answers

What secondary infections can result from larvae invading wounds or ulcers?

<p>Secondary infections may include purulent discharge and the potential for further tissue damage.</p> Signup and view all the answers

How can intestinal myiasis occur through food contamination?

<p>Intestinal myiasis may occur if flies deposit eggs or larvae on food, which are then accidentally ingested.</p> Signup and view all the answers

Name two types of flies that are known to cause myiasis in humans.

<p>Calliphora and Sarcophaga are two types of flies known for causing myiasis.</p> Signup and view all the answers

What potential complications can arise from larvae invading the urinary tract?

<p>Complications may include obstruction to urine flow, dysuria, and inflammation in the urinary passage with pus or blood in urine.</p> Signup and view all the answers

How can fly larvae cause damage to the eye during ocular myiasis?

<p>Larvae can invade the eye causing severe pain, lacrimation, and conjunctival irritation.</p> Signup and view all the answers

What is the typical path of entry for larvae when causing intestinal myiasis in children?

<p>Larvae typically enter through the anus, especially in rural areas, or via food contaminated with fly eggs or larvae.</p> Signup and view all the answers

What happens to larvae that invade human tissue when they encounter living skin?

<p>They can invade intact skin, leading to boil-like lesions.</p> Signup and view all the answers

What type of biological interactions occur when flies lay eggs on necrotic tissue?

<p>Flies may oviposit on dead tissues, leading to accidental ingestion and subsequent intestinal myiasis.</p> Signup and view all the answers

Which flies are primarily associated with causing myiasis through invasion of healthy tissues?

<p>Flies such as Wohlfahrtia, Chrysomia, and Cordylobia are known to invade living tissues.</p> Signup and view all the answers

Describe the role of exudates from neglected wounds in attracting flies that cause myiasis.

<p>Offensive exudates from neglected wounds can attract flies that lay eggs or larvae, starting the myiasis process.</p> Signup and view all the answers

What are some symptoms that may indicate the presence of larvae in the middle ear?

<p>Symptoms may include purulent discharge from the ear, pain, and possible hearing loss.</p> Signup and view all the answers

What are the primary symptoms associated with external otitis caused by fly larvae?

<p>Symptoms include inflammation and discomfort in the ear, producing excessive discharge.</p> Signup and view all the answers

What consequences can occur if larvae invade the cornea?

<p>The invasion of larvae in the cornea can lead to conjunctivitis and corneal ulcers.</p> Signup and view all the answers

What is the potential outcome of obstructive larvae in the nasal passages?

<p>Obstruction can cause persistent bloody purulent discharge and difficulty in breathing.</p> Signup and view all the answers

How can the identification of a larval species aid in diagnosing myiasis?

<p>Identifying the species by examining their posterior spiracles can help determine the type of myiasis.</p> Signup and view all the answers

What role do insecticides play in preventing myiasis?

<p>Insecticides help control fly populations that might deposit larvae on humans.</p> Signup and view all the answers

What is the clinical significance of larvae found in a wound?

<p>Finding larvae indicates a case of myiasis, which may require surgical intervention.</p> Signup and view all the answers

Explain how larvae can affect the healing process of affected tissues.

<p>Larvae presence can inhibit healing and induce sepsis in the infected tissues.</p> Signup and view all the answers

What distinguishes specific cutaneous myiasis from accidental cutaneous myiasis?

<p>Specific cutaneous myiasis occurs with known species, while accidental involves unspecified larvae.</p> Signup and view all the answers

Study Notes

Myiasis

  • Myiasis is the infection of human tissues by fly larvae (maggots).
  • Myiasis can be classified according to the habitat (site of invasion) and the biological habit of the fly.

Classification of Myiasis

  • Internal myiasis: Larvae invade internal organs like the intestines, urinary tract, etc.
    • Intestinal myiasis: Larvae are found within the intestines, often following ingestion of food containing larvae.
    • Urogenital myiasis: Larvae enter through urinary or genital orifices, causing obstructions and inflammation.
    • Signs/symptoms include nausea, vomiting, abdominal discomfort. Affected individuals may have living/dead larvae in stools/vomitus. Fannia (latrine fly) larvae are often involved.
  • External myiasis: Larvae invade external parts of the body, like the skin, ears, eyes, etc.
    • Cutaneous myiasis: Larvae infect wounds, ulcers, or even healthy skin, causing boil-like lesions and potentially serious damage.
      • Signs/Symptoms include skin lesions, ulcers, and potentially serious damage. Flies include Wohlfahrtia, Chrysomia, Cordylobia, Dermatobia, and Hypoderma.
    • Ocular Myiasis: Larvae are attracted to eye discharge and can reach the brain, causing severe pain, lacrimation, and conjunctival irritation. Flies include Calliphora and Sarcophaga.
    • Nasopharengeal Myiasis: Larvae are attracted to nasal discharge.
    • Aural Myiasis: Larvae infect the ear canal, middle ear, or inner ear due to purulent exudates. Involved flies include Wohlfahrtia, Sarcophaga, Lucilia, and Chrysomia.

Myiasis According to the Biological Habit of the Fly

  • Specific Myiasis (Obligatory Myiasis): Larvae only invade living tissues. Examples are Hypoderma and Dermatobia.
  • Semi-specific (Facultative Myiasis): Flies typically lay eggs/larvae on dead tissues; attracted by offensive discharge. Examples include Sarcophaga, Lucilia, Calliphora, Wohlfahrtia, Chrysomia.
  • Accidental Myiasis (Pseudomyiasis): Fly eggs/larvae are accidentally ingested or deposited around orifices like anal or urogenital orifices. Examples include Piophila (cheese), Drosophila, and Fannia (latrine fly).

Diagnosis of Myiasis

  • Clinical picture based on the tissue infected.
  • Physical identification of the larvae and their position.
  • Identification by posterior spiracles (breathing holes on larvae).
  • Breeding of larvae to adult stage for confirmation (species identification).

Treatment of Myiasis

  • Removal of larvae (by surgical excision or endoscopy).
  • Treatment of secondary infection (using antiseptics/antibiotics).

Prevention and Control of Myiasis

  • Use insecticides and nets to control the fly population.
  • Protect food sources from flies.
  • Clean and cover wounds/ulcers with gauze and dressings.

Questions

  • Question 1: Which fly species usually deposits larvae at urinary/genital orifices? The correct answer is Fannia.
  • Question 2: A 22-year-old male with an open wound, offensive discharge, and larvae present has what kind of myiasis? The correct answer is semi-specific cutaneous myiasis.

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