Parasitology and Medical Entomology: Amoebae and Diseases
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Questions and Answers

What is the primary method of diagnosis for Acanthamoeba keratitis?

  • Brain biopsy
  • Blood test
  • Culturing of CSF
  • Wet mount of corneal scrapings (correct)
  • Which of the following is a clinical feature of Granulomatous amoebic encephalitis (GAE)?

  • Hypertension
  • Seizures (correct)
  • Diarrhea
  • Cardiac arrest
  • What is the primary site of infection for Balamuthia mandrillaris in humans?

  • Respiratory tract (correct)
  • Muscular system
  • Gastrointestinal tract
  • CNS
  • What is the typical outcome of Acanthamoeba keratitis if left untreated?

    <p>Permanent visual impairment or blindness</p> Signup and view all the answers

    Which of the following is a prevention method for Acanthamoeba keratitis?

    <p>Avoiding tap water to rinse contact lenses</p> Signup and view all the answers

    What is the shape of the trophozoite of Balamuthia mandrillaris?

    <p>Irregular</p> Signup and view all the answers

    What is the primary cause of primary amoebic meningoencephalitis (PAM)?

    <p>Naegleria fowleri</p> Signup and view all the answers

    Where is Naegleria fowleri typically found?

    <p>Warm water (e.g. hotsprings) and soil</p> Signup and view all the answers

    What is the shape of the trophozoite form of Naegleria fowleri?

    <p>Amoeboid</p> Signup and view all the answers

    What is the function of the flagellate form of Naegleria fowleri?

    <p>Motile form in distilled water</p> Signup and view all the answers

    How does the trophozoite of Naegleria fowleri replicate?

    <p>Promitosis</p> Signup and view all the answers

    How does the trophozoite of Naegleria fowleri migrate to the brain?

    <p>Via the olfactory nerves</p> Signup and view all the answers

    What is the primary source of infection for Naegleria fowleri?

    <p>Swimming in warm freshwater lakes and rivers</p> Signup and view all the answers

    What type of stain can be used to examine Naegleria fowleri?

    <p>Giemsa</p> Signup and view all the answers

    What is the typical size of an Acanthamoeba trophozoite?

    <p>20–50 μm</p> Signup and view all the answers

    How do humans typically acquire Acanthamoeba infection?

    <p>Through inhalation of cysts or trophozoites</p> Signup and view all the answers

    What is the characteristic feature of Acanthamoeba cysts?

    <p>They have a polygonal double wall</p> Signup and view all the answers

    What is the primary habitat of Acanthamoeba species?

    <p>Central nervous system and eyes</p> Signup and view all the answers

    Study Notes

    Acanthamoeba Species

    • Produce granulomatous amoebic encephalitis (GAE) in immunodeficient patients, which can be fatal within days
    • Cause keratitis in healthy individuals, often associated with contact lens use
    • Can result in permanent visual impairment or blindness

    Acanthamoeba Species Pathogenesis and Clinical Features

    • GAE: seizures, paresis, and mental deterioration
    • Acanthamoeba keratitis: corneal infection in healthy individuals

    Acanthamoeba Species Diagnosis

    • GAE: trophozoites and cysts in brain biopsy, culture, or immunofluorescence microscopy
    • Acanthamoeba keratitis: cyst in corneal scrapings by wet mount, histology, or culture

    Acanthamoeba Species Prevention and Control

    • Do not use tap water to rinse contact lenses

    Balamuthia mandrillaris

    • Found in soil
    • Habitat: CNS
    • Morphology:
      • Trophozoite: 12-60 μm, irregular shape, motile by broad pseudopodia
      • Cyst: 6-20 μm, spherical with outer irregular wall and inner smooth wall
    • Infection through respiratory tract, skin lesions, or eyes
    • Life cycle similar to Acanthamoeba spp.

    Naegleria fowleri

    • Causes primary amoebic meningoencephalitis (PAM) in healthy individuals
    • Found in warm water (e.g., hot springs) and soil worldwide
    • Habitat: CNS
    • Morphology:
      • Trophozoite: 10-20 μm, amoeboid with rounded pseudopodia and spherical nucleus
      • Cyst: spherical
    • Life cycle:
      1. Cyst
      2. Trophozoite (amoeboid and flagellate forms)
      3. Flagellated form
      4. Trophozoite replication by promitosis
      5. Trophozoite penetration of nasal mucosa
      6. Trophozoite migration to brain via olfactory nerves
    • Infection occurs through swimming, diving, or nasal irrigation in contaminated water

    Naegleria fowleri Diagnosis

    • CSF examination:
      • Wet film examination for motile trophozoites
      • Fixed smear staining with Giemsa or modified trichrome stain
    • Culture
    • Molecular diagnosis: PCR on CSF specimen

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    Description

    This quiz covers the basics of parasitology and medical entomology, focusing on amoebae and the diseases they cause, including primary amoebic meningoencephalitis and granulomatous amoebic encephalitis.

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