PHA3109 Parasitology Overview
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Questions and Answers

How are the cysts of Entamoeba histolytica spread?

  • Through airborne droplets
  • Through contaminated food and water (correct)
  • Through direct contact with an infected person
  • Through insect bites

    • What is the defining characteristic of an ameboma?

  • A granulomatous lesion usually found in the cecum or rectosigmoid region (correct)
  • A large ulcerated area in the intestinal lining
  • A cyst formation in the intestinal wall
  • A small, localized area of inflammation in the intestinal wall

    • What is the primary mode of entry for Entamoeba histolytica into the human body?

  • Through a bite of an infected insect
  • Penetration through the skin
  • Ingestion of cysts (correct)
  • Inhalation of airborne cysts

    • Which of the following is a clinical manifestation of a liver abscess caused by Entamoeba histolytica?

    <p>Fever and chills (C)</p> Signup and view all the answers

    How does Entamoeba histolytica cause damage to the intestinal epithelium?

    <p>By secreting enzymes that cause localized necrosis and inflammation (D)</p> Signup and view all the answers

    Which of the following describes the trophozite form of a protozoan?

    <p>A motile, metabolically active form that feeds and reproduces. (D)</p> Signup and view all the answers

    Which of the following is NOT a method of transmission for helminths?

    <p>Transmission through contaminated water (C)</p> Signup and view all the answers

    What is the defining characteristic used to categorize protozoa?

    <p>Site of infection within the host (D)</p> Signup and view all the answers

    Which of the following is a characteristic of the cyst form of a protozoan?

    <p>It is surrounded by a thick wall and can survive in the environment. (B)</p> Signup and view all the answers

    What is the main difference between a definitive host and an intermediate host?

    <p>The definitive host is where the parasite reproduces sexually, the intermediate host is where the parasite reproduces asexually. (C)</p> Signup and view all the answers

    What are the two main phyla that helminths are categorized under?

    <p>Platyhelminthes and Nemathelminths (A)</p> Signup and view all the answers

    Which of the following is NOT a common method of management for parasitic infections?

    <p>Antibiotic treatment (C)</p> Signup and view all the answers

    What type of motility is characteristic of protozoa that are classified as "flagellated"?

    <p>They move by using flagella. (A)</p> Signup and view all the answers

    What is the primary method for diagnosing Cryptosporidium hominis infection?

    <p>Oocysts in fecal smears (D)</p> Signup and view all the answers

    Which of the following treatments is effective for patients without HIV infected by Cryptosporidium hominis?

    <p>Nitazoxanide (C)</p> Signup and view all the answers

    Which statement regarding Cryptosporidium hominis prevention is accurate?

    <p>Water purification by filtration is recommended. (D)</p> Signup and view all the answers

    What mechanism does nitazoxanide primarily utilize against protozoa?

    <p>Disrupts mitochondrial membrane potential (B)</p> Signup and view all the answers

    What is a characteristic feature of Trichomonas vaginalis?

    <p>Pear-shaped trophozoite (C)</p> Signup and view all the answers

    What type of stool sample is typically examined for the diagnosis of Entamoeba histolytica?

    <p>Both diarrheal and formed stool (D)</p> Signup and view all the answers

    What is the primary treatment method for trichomoniasis?

    <p>Tinidazole or metronidazole (C)</p> Signup and view all the answers

    Which treatment is effective for both intestinal amebiasis and hepatic abscesses caused by Entamoeba histolytica?

    <p>Metronidazole (D)</p> Signup and view all the answers

    Which organism is the only known reservoir for Trichomonas vaginalis?

    <p>Human genital tract (D)</p> Signup and view all the answers

    How does paromomycin exert its effect against protozoa?

    <p>Binds to 16S ribosomal RNA (B)</p> Signup and view all the answers

    What is a key characteristic symptom of giardiasis caused by Giardia lamblia?

    <p>Watery, foul-smelling diarrhea (C)</p> Signup and view all the answers

    What method is NOT effective in preventing contamination from Giardia lamblia?

    <p>Chlorination (B)</p> Signup and view all the answers

    In immunocompromised patients, what is the effect of Cryptosporidium hominis infection?

    <p>Severe malnutrition and dehydration (B)</p> Signup and view all the answers

    Which of the following best describes the mechanism of infection for Giardia lamblia?

    <p>Ingestion of cysts followed by excystation (A)</p> Signup and view all the answers

    Which treatment option is recommended for carriers of Entamoeba histolytica cysts?

    <p>Paromomycin (C), Iodoquinol (D)</p> Signup and view all the answers

    What is a prevention measure that can effectively kill the cysts of Entamoeba histolytica?

    <p>Boiling the water (C)</p> Signup and view all the answers

    Study Notes

    Parasitology Overview

    • PHA3109 Microbiology & Immunology Q3 2025
    • Chapters covered
      • Chapter 51: Intestinal and Urogenital Protozoa
      • Chapter 52: Blood and Tissue Protozoa
      • Chapter 54: Cestodes
      • Chapter 55: Trematodes
      • Chapter 56: Nematodes

    Parasite Classification

    • Parasites thrive at the host's expense, coming in two eukaryotic forms
      • Single-celled protozoa
      • Multicellular metazoa (worms = helminths)
    • Protozoa categorized by infection site
    • Metazoa categorized by worm type (2 phyla):
      • Platyhelminthes (flatworms)
      • Nemathelminths (roundworms)

    Protozoa Groups

    • Sarcodina (amoebas): unicellular, move by pseudopodia
    • Sporozoa (sporozoans): unicellular, nonmotile
    • Mastigophora (flagellates): unicellular, flagellated
    • Ciliata (ciliates): unicellular, ciliated
      • Trematoda (flukes) -Cestoda (tapeworms)

    Protozoa Terminology

    • Trophozoite: active, feeding, reproducing protozoan form with a flexible membrane
    • Cyst: dormant, non-reproducing stage; surrounded by a thick wall, enabling survival in the environment
    • Promastigotes/trypomastigotes: flagellated forms of certain protozoa
    • Amastigotes: non-flagellated forms of certain protozoa

    Transmission and Management

    • Intestinal protozoa transmission
      • Ingestion of cysts
    • Blood protozoa transmission
      • Insect vectors
    • Helminth transmission
      • Ingestion of eggs
      • Penetration of skin by larvae
      • Insect bite
    • Disease management focuses on interrupting transmission
      • Sanitation
      • Water Purification
      • Insect Management
      • Personal Protective Measures

    Intestinal and Urogenital Protozoa

      1. Intestinal tract:
      • Entamoeba histolytica (amoeba)
      • Giardia lamblia (flagellate)
      • Cryptosporidium hominis (sporozoan)
      1. Urogenital tract:
      • Trichomonas vaginalis (flagellate)

    Intestinal Protozoa - Entamoeba histolytica

    • Causes amebic dysentery and liver abscess
    • Symptoms range from dysentery to liver abscess
    • Important properties
      • Trophozoites and cysts
      • Cysts have four nuclei
    • Diagnosis
      • Examine stool for trophozoites or cysts
    • Treatment
      • Metronidazole or tinidazole
    • Prevention
      • Handwashing, avoid contamination of food and water.
      • Cyst-killing techniques: boiling, filtration

    Intestinal Protozoa - Giardia lamblia

    • Causes giardiasis: watery, foul-smelling, non-bloody diarrhea
    • Pathogenesis involves ingestion of cysts and excystation in duodenum, resulting in trophozoite attachment with inflammation & malabsorption
    • Diagnosis
      • Examine stool for trophozoites or cysts (string test)
    • Treatment
      • Tinidazole, metronidazole
    • Prevention
      • Boil or filter water and avoid consumption of contaminated foods

    Intestinal Protozoa - Cryptosporidium hominis

    • Causes cryptosporidiosis: severe watery diarrhea in immunocompromised populations and milder self-limiting symptoms in healthy individuals
    • Pathogenesis: ingestion of oocysts, excystation in small intestine, and trophozoite attachment to gut wall.
    • Treatment
      • Nitazoxanide
    • Prevention
      • Filtered or boiled water, hygiene

    Blood/Tissue Protozoa

    • Incidence data (by specific protozoan) for the U.S. and worldwide is provided.

    Blood/Tissue Protozoa - Malaria

    • Malaria is caused by four species of Plasmodium. P. falciparum is the most severe. Significant morbidity and mortality.
    • Lifecycle involves the mosquito vector, human liver, and human blood stages.
    • Symptoms include fever, chills, headache, and other systemic symptoms. Can cause extensive brain and kidney damage.
    • Complicated by developing drug resistance.

    Blood/Tissue Protozoa - Toxoplasma gondii

    • Causes toxoplasmosis.
      • Congenital toxoplasmosis (in uteros) can have severe outcomes.
      • Immunocompetent adults are typically asymptomatic.
      • Immunocompromised individuals may develop severe, life-threatening disease.
    • Pathogenesis involves cyst rupture in the gut, macrophage engulfment, and tachyzoite proliferation into tissues.
    • Treatment:
      • Sulfadiazine, pyrimethamine.

    Blood/Tissue Protozoa - Pneumocystis jiroveci

    • Formerly classified as a fungus, now known to be a related form of yeast.
    • Causes pneumocystis pneumonia in immunocompromised individuals.
    • Transmission: inhalation, infection in the lungs
    • Treatment
      • Trimethoprim-sulfamethoxazole, and Pentamidine
    • Prevention
      • Immunosuppression control

    Parasitic Helminths - Platyhelminthes

    • Platyhelminthes are flatworms, classified into cestodes (tapeworms) and trematodes (flukes)
    • Important structure
      • Scolex: head with hooks and suckers
      • Proglottids: body segments; contain eggs

    Cestodes - Taenia solium

    • Adults cause taeniasis; larvae cause cysticercosis
    • Pathogenesis involves ingestion of eggs, development in the gut, and migration to tissues.
    • Symptoms
      • Taeniasis: mostly asymptomatic, but can include pain, weight loss, blockage.
      • Cysticercosis: variable ranging from headache and vomiting to blindness and neurological damage.
    • Treatment
      • Praziquantel, albendazole (sometimes surgical excision)
    • Prevention
      • Thoroughly cooking pork and managing human waste.

    Cestodes - Treatment

    • Praziquantel: Increases schistosome membrane permeability for calcium ions
    • Albendazole: Binds beta-tubulin, inhibiting microtubule assembly

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    Parasitology PHA3109 Microbiology & Immunology Q3 2025 PDF

    Description

    Test your knowledge on parasitology with content from the PHA3109 Microbiology & Immunology course for Q3 2025. This quiz covers various types of parasites including protozoa and helminths, their classifications, and key terminology. Challenge yourself on the details of intestinal and urogenital protozoa, blood and tissue protozoa, and more!

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