1. Sample Collection and Handling
Parasitology
Sample Collection and Handling
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

2. Parasite Detection
Parasites infect the oral cavity, esophagus, stomach, small and large intestine, and other internal organs
Detected through microscopic examination of feces
Life stage found in feces
Eggs, oocysts, larvae, segments (tapeworms), and adult organisms
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

3. Collection of Fecal Samples
Fresh samples are best
If cannot be completed within a few hours
Should be refrigerated or mixed with 10% formalin
Older samples – the appearance of eggs, oocysts, or other life cycle stages may be altered due to parasite development
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

4. Small Animal Fecal Samples
Several methods
Owner collection immediately after defecation
Stored in disposable container
About 1 g (thimble-sized) is needed
Labeled properly
Collected directly from animal in hospital
Gloved finger or fecal loop
Fecal loop used for direct smear – small amount
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

5. Samples Sample should be as fresh as possible
Label – client name, date of collection, species, animal identification
Examine samples within 24 hours
Precautions
Wear gloves and protective outerwear
Prevents contamination of samples
Ensures personal health
Wash gloves frequently with soap and water
Clean and disinfect work areas and equipment
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

6. Records Maintenance of good records are important
Records should include:
Identification information
Procedures performed
Results
Should also include:
Adequate history
Clinical signs
Duration of signs
Medications given
Environment
Vaccinations
Stocking density
Number of animals affected
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

7. Equipment
Microscope is the most reliable method of detection of parasitic infections
Binocular microscope with x10, x40, and x100 objectives
Calibrated ocular micrometer
Stereo microscope is also helpful
Glass slides
View sample systematically
x10 objective to start
Many parasites in the same plane as air bubbles or at the edge of the coverslip
Once a parasite is located, examine at higher magnification
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

8. Evaluation of Fecal Specimens
The choice of test to be performed is dependent on clinical signs and patient history
Begin with a gross examination of the sample
Consistency
Color
Presence of blood
Mucus
Odor
Adult parasites
Foreign bodies
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

9. Direct Smear Simplest Requires minimal equipment
Allows for visualization of trophozoite stages of protozoal parasites – Giardia
Not adequate examination
Disadvantages
Small sample size
Debris may be confused with parasitic material
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

10. Direct Smear (cont.)
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

11. Fecal Flotation
Based on differences in specific gravity of life cycle stages of parasites
Flotation solutions have a higher specific gravity then common ova
Ova float to surface
Fluke eggs have a higher S.G. and sink
Too high an S.G. creates a plug of debris that traps parasites, obscuring them from view
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

12. Fecal Flotation (cont.)
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

13. Fecal Flotation (cont.)
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

14. Centrifugal Flotation
Similar to flotation except once mixed the sample is strained to remove excess debris
Requires a tabletop centrifuge
More sensitive than simple flotation
Recovers more eggs and cysts in less time
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

15. Centrifugal Flotation (cont.)
Giardia
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

16. Fecal Sedimentation
Used when suspected ova are too large to be recovered with standard flotation
Fluke ova
Laborious technique
Most fluke eggs do not float or they are distorted by flotation solutions, making them difficult to recognize
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

17. Fecal Sedimentation (cont.)
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

18. Cellophane Tape Preparation
Often used to recover ova from Oxyuris –pinworms and tapeworms
Tape wrapped around a tongue depressor with adhesive side out
Animal’s tail raised and tongue depressor pressed firmly against the anus
Tape then removed and applied to a slide with a small amount of water
Examine microscopically
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

19. Baermann Technique Used to recover larvae from fecal samples
Requires the construction of a Baermann apparatus
Large funnel, tubing,
and collection tube
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

20. Baermann Technique (cont.)
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

21. Baermann Technique (cont.)
Routinely performed on feces of domestic animals when lungworm infections are suspected
Fresh samples collected rectally
In dogs and cats, Baermann technique is used when Strongyloides are suspected
Zoonotic potential
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

22. Miscellaneous Fecal Examinations
Some parasites produce intestinal bleeding
Evident by frank blood in feces or darkened feces
Some intestinal bleeding can only be identified with chemical testing
Occult blood testing
Many kits available
Identify the presence of hemoglobin
Vomitus can also aid in diagnosis of parasites
Toxocara canis
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

23. Miscellaneous Fecal Examinations (cont.)
Fecal culture
Used to differentiate parasites whose eggs or larvae are not easily distinguished by a fresh fecal sample
Because the life cycle, pathogenicity, and epidemiology of some species differ, identification may be necessary for proper treatment and control
May need an experienced helminthologist
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

24. Fecal Culture
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

25. Miscellaneous Fecal Examinations (cont.)
Modified McMasters technique
Provides an estimate of the number of eggs or oocysts per gram of feces
Used mainly in livestock and horses
Originally adapted from a technique used in people infected with hookworms
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

26. Modified McMasters Technique
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

27. Staining Procedures
Stains may be used to recognize certain structural characteristics of trophozoites and cysts
Lugol iodine and new methylene blue commonly used with direct smear
Do not preserve the slide
Help with identification
If protozoal parasites cannot be identified on direct smears
Fecal smears with suspected trophozoites can be dried and stained with Diff-Quik or Wright or Giemsa stain and sent to a diagnostic laboratory
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

28. Staining Procedures (cont.)
Acid-fast staining is used to identify Cryptosporidium sp.
Cryptosporidium is a parasite of the intestinal tract of many animals including humans
Diff-Quik stain can be used to aid in identification of Isospora sp.
Intestinal mucosal scrapings
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

29. Summary
Methods to examine fecal specimens include gross and direct microscopic examinations
Other examinations include fecal flotation, centrifugal flotations, and sedimentation
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.