Procedures

The analytic procedures in parasitology are a toolbox of techniques that help us identify and understand parasitic infections. By choosing the right tools and using them effectively, we can provide accurate diagnoses, guide treatment decisions, and protect public health

Specimen Sources: “Where Do We Look?”

• The Goal: Choosing the right sample to maximize our chances of finding the parasite
• Key Specimens
  • Stool (for intestinal parasites)
  • Blood (for blood-borne parasites)
  • Tissue (for parasites that invade organs)
  • Respiratory samples (sputum, BAL)
  • Urine, genital swabs, CSF, corneal scrapings (for specific parasites)
• Key Considerations
  • Knowing where the parasite is likely to be located in the body
  • Proper collection, preservation, and transport

Major Pathogens and Disease States: “Who Are We Hunting?”

• The Goal: Understanding the parasites we’re likely to encounter, the diseases they cause, and how they spread
• Key Categories
  • Blood and Tissue Protozoa (Plasmodium, Trypanosoma)
  • Intestinal and Urogenital Protozoa (Giardia, Entamoeba, Cryptosporidium, Trichomonas)
  • Intestinal and Tissue Helminths (Ascaris, Enterobius, hookworm, Schistosoma, Taenia, Trichinella)
  • Brain-Invading Parasites (Toxoplasma, Naegleria, Acanthamoeba)
  • Insects and Arthropods (Ticks, Mites, Lice, Bed Bugs)
  • Additional Parasites (Filariae, Flukes)
• Key Information
  • Etiology (cause)
  • Epidemiology (how it spreads)
  • Transmission (how it infects)
  • Disease manifestations

Microscopic and Macroscopic Identification: “What Do They Look Like?”

• The Goal: Using our eyes (and microscopes!) to identify parasites based on their physical characteristics
• Macroscopic Examination
  • Observing specimens with the naked eye or low magnification
  • Looking for worms, arthropods, or unusual stool consistency
• Microscopic Examination
  • Using microscopes to observe specimens at higher magnification
  • Key Features:
    • Protozoa: Size, shape, nuclear structure, cytoplasmic inclusions, motility (trophozoites and cysts)
    • Helminths: Size, shape, shell characteristics, internal contents (eggs and larvae)
    • Arthropods: Size, shape, appendages, body structures
• Key Techniques
  • Direct wet mounts, concentration techniques, staining techniques (iodine, trichrome, Giemsa)

Direct Antigen and Molecular Detection: “Can We Detect Their Signature?”

• The Goal: Using immunological and molecular techniques to detect parasite antigens or DNA/RNA
• Direct Antigen Detection
  • Using antibodies to detect specific parasite antigens
  • Methods: ELISA, ICA, DFA
  • Advantages: High specificity, rapid turnaround time
  • Disadvantages: Limited sensitivity, potential for cross-reactivity
• Molecular Detection
  • Using nucleic acid amplification techniques (NAATs) to detect parasite DNA or RNA
  • Methods: PCR, real-time PCR, LAMP
  • Advantages: High sensitivity, high specificity, multiplexing, quantitation
  • Disadvantages: Complexity, cost, potential for contamination
• Key Considerations
  • Choosing the right method based on the clinical situation and available resources

Culture: “Can We Grow Them?”

• The Goal: Growing parasites in a controlled environment to increase their numbers for identification and study
• Key Organisms
  • Trichomonas vaginalis
  • Strongyloides stercoralis
• Advantages
  • Increased sensitivity (especially for low-level infections)
  • Aid in identification
  • Essential for research
• Disadvantages
  • Time-consuming
  • Requires technical expertise
  • Susceptible to contamination
  • Not available for all parasites