Introduction to Parasitology Student Lab Division of Medical

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Introduction to Parasitology

• Student Lab
• Division of Medical Technology
• Carol Larson MSEd, MT(ASCP)

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3 Categories of Parasites

• Protozoa (single celled)
• Worms
• Nematodes roundworms
• Trematodes flatworms, non-segmented
• Cestodes tapeworms, segmented flatworms
• Ectoparasites
• Flea, mosquito, fly, lice

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Videotape Discussion

• Means of transmission
• Groups at risk
• Methods of control prevention
• Roles of medical technologist

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Means of Transmission

• Fecal-oral
• Direct (person to person)
• Food, water
• Encysted larvae in meat, fish
• Insect vectors
• Sexually
• Penetrate skin organism in soil water

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Other Factors in Transmission

• Political social changes
• Economy (third-world)
• War
• Refugees
• Behavioral patterns of living
• Dietary habits
• Customs, traditions

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Videotape Discussion

• Means of transmission
• Groups at risk
• Methods of control prevention
• Roles of medical technologist

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Groups at Risk

• 3rd world countries
• Refugees
• Exposure to insect vectors
• Lifestyles
• Customs related to raw meat/fish
• Farmers and others handling animals
• Multiple sex partners / homosexuals

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Groups at Risk

• Immunocompromised patients
• AIDS patients
• Transplant patients
• Lymphoma and other cancer patients

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Videotape Discussion

• Means of transmission
• Groups at risk
• Methods of control prevention
• Roles of medical technologist

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Methods of Control Prevention

• Adequate inspection of food products
• Changes in dietary habits
• Cook food thoroughly
• Improvement of sanitation
• Boil or filter water
• Changes in farming practices
• Livestock care handling

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Methods of Control Prevention

• Avoid insect bites
• Insecticides
• Destruction of breeding sites
• Chemoprophylactic drugs
• Education of the public
• Hand washing
• Avoid walking barefoot in endemic areas
• Avoid swimming in endemic areas

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Videotape Discussion

• Means of transmission
• Groups at risk
• Methods of control prevention
• Roles of medical technologist

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Roles of Medical Technologist

• Diagnosis
• Develop tests
• Implement (perform) tests
• Evaluate tests
• Investigation
• Education

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In Summary

• Means of transmission
• Groups at risk
• Methods of control prevention
• Roles of medical technologist

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Parasitology Stool Specimens

• Student Lab
• Division of Medical Technology
• Carol Larson MSEd, MT(ASCP)

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Specimen Types

• Stool (feces)
• Duodenal material
• Sigmoidoscopic material

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Specimen Collection

• Fresh specimen
• Liquid
• Examine within 30 minutes for trophs
• Formed
• Can store in refrigerator for 24 hours
• Preserved specimen
• Any delay in examination

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Specimen Collection

• Number of specimens
• If first specimen negative, collect up to two
  more specimens
• Time between specimens
• Every other day
• Why?

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Specimen Collection

• Container
• Rejection Criteria
• Labeling
• Barium
• Urine

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Specimen Collection

• Preservatives
• 10 Formalin
• PVA
• MIF
• One vial fixatives
• Safety
• Follow standard precautions

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Fresh Specimen - Four Steps
Routine OP Examination

• Macroscopic Examination
• Microscopic Examination
• Direct examination wet mounts
• Concentration procedure
• Permanent staining procedure

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Macroscopic Examination
Routine OP Examination

• Fresh specimen
• Appearance
• Consistency
• Color

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Microscopic Examination
Routine OP Examination

• Ocular micrometer calibration
• Direct examination - wet mounts
• Scan on low power, evaluate on high power
• Saline
• Motility
• Iodine
• Stains internal structures

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Microscopic Examination
Routine OP Examination

• Concentration procedures
• Formalin-ethyl acetate sedimentation
• Recover all ova, cysts and larvae
• Very junky preparation
• DO NOT recover trophs
• Zinc sulfate flotation

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Microscopic Examination
Routine OP Examination

• Permanent stains
• Wheatleys Trichrome stain
• Iron hematoxylin stain
• Modified acid fast stain

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Preserved Specimen - 3 Steps
Routine OP Examination

• Microscopic Examination
• Direct examination wet mounts (iodine only)
• Concentration procedure
• Permanent staining procedure

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Testing of fecal specimenspreserved in formalin
and PVA
Wet mount (helminths, protozoa) Immunoassay
(Giardia, Cryptosporidium) Chromotrope stain
(Microsporidia)
Specimens in 10 formalin
Wet mount (helminths protozoa) Direct mount
(epifluorescence Cyclospora, Isospora) Acid
fast stain (Cryptosporidium, Cyclospora,
Isospora) Direct immunofluorescent assay
(Giardia, Cryptosporidium) Safranin
stain (Cyclospora)
Formalin-ethyl acetate concentration
Specimens in PVA fixative
Trichrome stain (protozoa)
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Other Tests for Intestinal Parasites

• Collection techniques
• Immunological / Serological techniques
• Molecular techniques

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Other Tests for Intestinal Parasites

• Collection Techniques
• Scotch tape preparation

• Entero-test (string test)

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Other Tests for Intestinal Parasites

• Serologic Techniques
• ELISA
• Direct and indirect immunofluorescence
• Indirect hemagglutination

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Other Tests for Intestinal Parasites

• Molecular Techniques
• DNA probes
• PCR
• RFLP
• Flow cytometry

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In Summary

• Specimen collection transport
• Macroscopic examination
• Microscopic examination
• Wet mounts
• Concentration
• Permanent stains
• Other tests