Medical Parasitology Overview
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Questions and Answers

Which type of parasite cannot exist without a host?

  • Accidental parasite
  • Facultative parasite
  • Obligate parasite (correct)
  • Microparasite
  • What type of host is responsible for the sexual reproduction of a parasite?

  • Accidental host
  • Reservoir host
  • Intermediate host
  • Definitive host (correct)
  • Which of the following is an example of a facultative parasite?

  • Plasmodium spp.
  • Echinococcus granulosus
  • Toxoplasma gondii
  • Naegleria fowleri (correct)
  • What term describes an organism that benefits from its host while causing injury?

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

    Which source of infection is associated with undercooked meat?

    <p>Raw or undercooked pork</p> Signup and view all the answers

    Which portal of entry involves inhalation?

    <p>Eggs of E. vermicularis</p> Signup and view all the answers

    Which of the following is an ectoparasite?

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

    What role does a vector play in the transmission of infection?

    <p>Transmits the infection from one host to another</p> Signup and view all the answers

    What is a common method of transmission for malaria parasites in a clinical setting?

    <p>Transfusion or contaminated syringes</p> Signup and view all the answers

    Which parasitic action can lead to intestinal obstruction?

    <p>Presence of A.lumbricoides and T.saginata</p> Signup and view all the answers

    What type of immune response is generally less efficient in parasitic infections compared to bacterial and viral infections?

    <p>Cell-mediated immunity (CMI)</p> Signup and view all the answers

    Which preservation solution is known to fix and preserve specimens for one year?

    <p>Schaudinn's solution</p> Signup and view all the answers

    Which of the following is a consequence of inflammation caused by parasitic infections?

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

    What type of staining can be used to demonstrate the presence of parasites in stool samples?

    <p>Lugol's iodine staining</p> Signup and view all the answers

    Which parasite is known to be associated with vesical carcinoma?

    <p>Schistosoma haematobium</p> Signup and view all the answers

    Which characteristic is true about lytic necrosis caused by E.histolytica?

    <p>It secretes lytic enzymes that lyse tissues</p> Signup and view all the answers

    What is the required method for collecting a stool specimen for examination?

    <p>Three faecal samples collected over three days</p> Signup and view all the answers

    How should liquid stool specimens be handled for examination?

    <p>They must be processed within 30 minutes</p> Signup and view all the answers

    Which staining method is NOT used in microscopic examination of stool specimens?

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

    What is the main purpose of using the Formalin-ether sedimentation technique?

    <p>To rupture cysts and eggs for better visualization</p> Signup and view all the answers

    Which technique is used to concentrate cysts of protozoa during stool examination?

    <p>Zinc sulphate centrifugal floatation technique</p> Signup and view all the answers

    What is the correct procedure time for examining formed stool specimens?

    <p>Within 24 hours</p> Signup and view all the answers

    What indicates the use of the flotation technique during stool examination?

    <p>It causes most helminthic eggs to float</p> Signup and view all the answers

    What is the correction factor for frankly diarrhoeic stool when calculating eggs per gram?

    <p>4</p> Signup and view all the answers

    Which method is used for quantifying worm burden in stool samples?

    <p>Stoll's method</p> Signup and view all the answers

    Which staining methods are used for blood samples to detect Plasmodium spp.?

    <p>Both A and B</p> Signup and view all the answers

    What is the first step in the triple centrifugation method for blood concentration?

    <p>Centrifuge 100g for 10 minutes</p> Signup and view all the answers

    Which of the following specimens is used to identify eggs of S. haematobium?

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

    What type of specimen can be examined for the presence of Acanthamoeba spp.?

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

    What is a common method used for detecting microfilariae in blood?

    <p>Membrane filtration</p> Signup and view all the answers

    Which of the following is NOT an example of molecular methods in diagnosis?

    <p>Skin Tests</p> Signup and view all the answers

    What is examined in the sediments after the triple centrifugation process?

    <p>Both A and B</p> Signup and view all the answers

    Study Notes

    Introduction to Medical Parasitology

    • Study of parasites affecting humans, the diseases they cause, and the host's response.
    • Emphasis on diagnosis methods and prevention strategies.

    Definition of Parasites

    • Parasites rely on a host for part or all of their life cycle and metabolic needs.
    • Categories include microparasites and macroparasites, based on size and impact.

    Types of Parasites

    • Ectoparasites: Live on the exterior (e.g., lice).
    • Endoparasites: Live within the host (e.g., protozoans and helminths).
    • Obligate Parasites: Depend entirely on a host (e.g., Toxoplasma gondii).
    • Facultative Parasites: Can live as free-living or parasitic forms (e.g., Naegleria fowleri).
    • Accidental Parasites: Infect an unusual host (e.g., Echinococcus granulosus in humans).

    Host Definitions

    • Definitive Host: Where sexual reproduction of the parasite occurs.
    • Intermediate Host: Hosts where larval or asexual stages develop.
    • Reservoir Host: Carries the parasite, providing a source of infection to other hosts.

    Vectors and Transmission

    • Vectors are often insects that transmit parasites; e.g., houseflies transmit E. histolytica.

    Host-Parasite Relationships

    • Symbiosis: Mutual dependence of host and parasite.
    • Commensalism: The parasite benefits without harming the host.
    • Parasitism: The parasite benefits at the expense of the host.

    Sources of Infection

    • Contaminated soil and water (e.g., eggs of A. lumbricoides).
    • Consumption of undercooked pork (e.g., T. solium).
    • Blood-sucking insects transmit Plasmodium spp., and others.
    • Animals act as sources (e.g., dogs and Echinococcus granulosus).

    Portals of Entry

    • Common entry points include the mouth (e.g., E. histolytica), skin (e.g., A. duodenale), and congenital transmission (e.g., T. gondii).

    Pathogenicity

    • Traumatic Damage: Caused by the physical presence of parasites (e.g., hookworm attachment).
    • Lytic Necrosis: Tissue damage from secreted enzymes (e.g., E. histolytica).
    • Allergic Manifestations: Due to parasite secretions and excretions.
    • Inflammatory Reactions: Produce eosinophilia and anemia.
    • Neoplasia: Schistosoma haematobium links to bladder cancer.
    • Secondary Infections: Migrating larvae can carry pathogens to tissues.

    Immunity in Parasitic Infections

    • Less effective than responses to bacterial and viral infections.
    • Cytotoxic T cells, Natural Killer cells, and antibodies (primarily IgM, IgG, IgE) play crucial roles.

    Preservation of Stool Specimens

    • Formalin Solution: 10% formalin saline; preserves cysts and eggs.
    • Polyvinyl Alcohol (PVA): Recommended for trichrome staining.
    • Merthionate-Iodine-Formalin (MIF): Excellent preservation for 1 year.
    • Schaudinn's Solution: Fixation and preservation for 1 year.

    Laboratory Diagnosis

    • Stool Examination: Techniques include wet mounts, concentration methods (e.g., salt flotation), and staining.
    • Collection of Specimens: Multiple stool samples collected over days, emphasizing timing post-bowel movements.

    Examination Methods

    • Macroscopic: Color, consistency, and presence of blood or mucus.
    • Microscopic: Staining techniques and direct examinations.

    Concentration Techniques

    • Floatation Technique: Cysts and eggs are concentrated in a solution.
    • Sedimentation Technique: Used for identifying thicker samples using formalin-ether.

    Quantification of Worm Burden

    • Methods include direct smear egg count and Stoll's method for estimating eggs per gram in stool.

    Blood Examination

    • Techniques for identifying parasitic infections include wet mounts and various staining methods.
    • Concentration methods help isolate parasites from blood samples.

    Other Biological Specimens

    • Urine, genital specimens, CSF, tissue biopsies, sputum, and cultures can also provide diagnostic information.

    Immunodiagnosis

    • Skin tests, serological tests for antibody detection, and molecular methods (e.g., PCR) enhance diagnostic capabilities.

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    Description

    This quiz covers the fundamentals of medical parasitology, including the types of parasites that infect humans, the diseases they cause, and the methods of diagnosis and prevention. Gain insights into both microparasites and macroparasites, as well as their classifications based on their location in or on a host.

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