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Questions and Answers
Which type of parasite cannot exist without a host?
Which type of parasite cannot exist without a host?
What type of host is responsible for the sexual reproduction of a parasite?
What type of host is responsible for the sexual reproduction of a parasite?
Which of the following is an example of a facultative parasite?
Which of the following is an example of a facultative parasite?
What term describes an organism that benefits from its host while causing injury?
What term describes an organism that benefits from its host while causing injury?
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Which source of infection is associated with undercooked meat?
Which source of infection is associated with undercooked meat?
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Which portal of entry involves inhalation?
Which portal of entry involves inhalation?
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Which of the following is an ectoparasite?
Which of the following is an ectoparasite?
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What role does a vector play in the transmission of infection?
What role does a vector play in the transmission of infection?
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What is a common method of transmission for malaria parasites in a clinical setting?
What is a common method of transmission for malaria parasites in a clinical setting?
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Which parasitic action can lead to intestinal obstruction?
Which parasitic action can lead to intestinal obstruction?
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What type of immune response is generally less efficient in parasitic infections compared to bacterial and viral infections?
What type of immune response is generally less efficient in parasitic infections compared to bacterial and viral infections?
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Which preservation solution is known to fix and preserve specimens for one year?
Which preservation solution is known to fix and preserve specimens for one year?
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Which of the following is a consequence of inflammation caused by parasitic infections?
Which of the following is a consequence of inflammation caused by parasitic infections?
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What type of staining can be used to demonstrate the presence of parasites in stool samples?
What type of staining can be used to demonstrate the presence of parasites in stool samples?
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Which parasite is known to be associated with vesical carcinoma?
Which parasite is known to be associated with vesical carcinoma?
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Which characteristic is true about lytic necrosis caused by E.histolytica?
Which characteristic is true about lytic necrosis caused by E.histolytica?
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What is the required method for collecting a stool specimen for examination?
What is the required method for collecting a stool specimen for examination?
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How should liquid stool specimens be handled for examination?
How should liquid stool specimens be handled for examination?
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Which staining method is NOT used in microscopic examination of stool specimens?
Which staining method is NOT used in microscopic examination of stool specimens?
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What is the main purpose of using the Formalin-ether sedimentation technique?
What is the main purpose of using the Formalin-ether sedimentation technique?
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Which technique is used to concentrate cysts of protozoa during stool examination?
Which technique is used to concentrate cysts of protozoa during stool examination?
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What is the correct procedure time for examining formed stool specimens?
What is the correct procedure time for examining formed stool specimens?
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What indicates the use of the flotation technique during stool examination?
What indicates the use of the flotation technique during stool examination?
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What is the correction factor for frankly diarrhoeic stool when calculating eggs per gram?
What is the correction factor for frankly diarrhoeic stool when calculating eggs per gram?
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Which method is used for quantifying worm burden in stool samples?
Which method is used for quantifying worm burden in stool samples?
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Which staining methods are used for blood samples to detect Plasmodium spp.?
Which staining methods are used for blood samples to detect Plasmodium spp.?
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What is the first step in the triple centrifugation method for blood concentration?
What is the first step in the triple centrifugation method for blood concentration?
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Which of the following specimens is used to identify eggs of S. haematobium?
Which of the following specimens is used to identify eggs of S. haematobium?
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What type of specimen can be examined for the presence of Acanthamoeba spp.?
What type of specimen can be examined for the presence of Acanthamoeba spp.?
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What is a common method used for detecting microfilariae in blood?
What is a common method used for detecting microfilariae in blood?
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Which of the following is NOT an example of molecular methods in diagnosis?
Which of the following is NOT an example of molecular methods in diagnosis?
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What is examined in the sediments after the triple centrifugation process?
What is examined in the sediments after the triple centrifugation process?
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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.
