Paralab

• What does confirmation of a suspected parasitic condition depend on?


  Proper laboratory examination results
• What factors affect the reliability of results in a parasitology laboratory?

  Collection, handling, processing, analyst skill, equipment quality
• Why might a parasite not be demonstrable in an active infection?

  Parasites may be immature or not present
• What is the most commonly utilized specimen for parasitic examinations?

  Stool
• What is the primary method of diagnosing intestinal parasites?

  Demonstration of eggs, larvae, or cysts in stool
• What type of container is best for collecting stool specimens?

  Clean, wide-mouthed plastic container with a lid
• What information should be submitted with a stool specimen?

  • Patient’s name
  • Age
  • Sex
  • Date/time of collection
  • Requesting physician
  • Requested procedure
  • Presumptive diagnosis
  • Prior infections
  • Travel history
• Why should stool samples be collected after a week of drug intake?

  Drugs can leave residues that interfere with identification
• How does antibiotic intake affect stool specimen analysis?

  It decreases the number of protozoans for weeks
• What is the recommended amount of stool for a routine examination?

  Thumb-sized specimen or 5-6 tablespoons
• Why must contamination with toilet water or soil be prevented?

  It can destroy protozoan trophozoites
• What is the significance of stool age for diarrheic specimens?

  Trophozoites die within 30 minutes to 1 hour
• What should be done if there is a delay in specimen examination?

  Preservation may be required to identify parasites
• What is the acceptable temporary storage condition for fecal samples?

  Refrigerator at 3-5°C
• Why should stool samples never be frozen?

  Freezing kills trophozoites
• What are the types of stool preservatives used?

  1. Formalin
  2. Schaudinn’s solution
  3. Polyvinyl alcohol (PVA)
  4. Merthiolate-iodine-formalin (MIF)
  5. Sodium acetate-acetic acid formalin (SAF)
• What is the recommended concentration of formalin for protozoan cysts?

  5% concentration
• What is the purpose of Schaudinn’s solution?

  To preserve fresh stool for staining
• What is the main advantage of using Polyvinyl alcohol (PVA)?

  Preservation of protozoan cysts and trophozoites
• What does Merthiolate-iodine-formalin (MIF) contain?

  Merthiolate, iodine, and formalin
• What is a disadvantage of Sodium acetate-acetic acid formalin (SAF)?

  Images are not as sharp after staining
• How should stool samples be submitted to the laboratory?

  In fresh state or as preserved samples
• What does the consistency of stool indicate?

  It indicates the stage of the organism present
• What are the types of macroscopic examination for stool specimens?

  Consistency and color
• Why is the presence of blood or mucus noted during examination?

  It may indicate underlying conditions
• What types of organisms are usually found in watery stools?

  Trophozoites
• What types of organisms are usually found in formed specimens?

  Cysts and helminth eggs
• What are the types of white blood cells observed in microscopic examination?

  Polymorphonuclears and eosinophils
• What do Charcot-Layden crystals indicate?

  Presence of hypersensitivity or parasitic infections
• What can be mistaken for human parasites during examination?

  Eggs of anthropods and plant nematodes
• What elements of plant origin can resemble parasites?

  Plant cells, pollen grains, starch granules
• What is the importance of examining the entire slide preparation?

  To detect eggs, larvae, and protozoa
• What is the purpose of using low power during microscopic examination?

  To scan for large helminth eggs or larvae
• How are detected parasites reported?

  By scientific name and quantity observed
• What does "NOOPS" stand for in reporting?

  No Ova or Parasite Seen
• What does "NIPS" stand for in reporting?

  No Intestinal Parasites Seen
• What is the suggested frequency distribution chart for protozoa and helminths?

  • Rare: 2 to 5 organisms per 22mm square
  • Few: 1 organism per 5 to 10 high-power fields
  • Moderate: 1 to 2 organisms per high-power field
  • Many: Several organisms in every high-power field
• What is the technique for Direct Fecal Smear (DFS)?

  Comminute stool with NSS and cover with slip
• What is the purpose of using a weak iodine solution in DFS?

  To demonstrate nuclei in protozoa
• What does the evaluation of saline direct mounts allow for?

  Study of motility of trophozoites