4- Worm egg counts and reduction tests Flashcards
What are faecal egg counts needed for
Detection & quantification of worm eggs
McMaster Technique
Faeces mixed in a flotation solution & loaded onto chambers of a slide
Floated eggs are counted
Advantages and limitations of direct faecal smear
Ad= clear, short processing time
Dis= qualitative, very low accuracy, precision and sensitivity
Advantages and limitations of Cornell-Wisconsin
Ad= Cheap high limit of detection
Lim= Time-consuming, low accuracy
Advantages and limitations of McMaster
Ad= Cheap, medium processing time
Dis= Sensitivity limit is 50 eggs/gram of faeces. Requires the use of a specialised light
Advantages and limitations of FLOTAC
Ad= Cheap high sensitivity
Lim= Time-consuming, requires a centrifuge
Advantages and limitations of Mini-FLOTAC
Ad= High sensitivity, accuracy and precision, medium processing time
Lim= Detection of some parasites (e.g. trematodes) requires centrifugation- so this method can’t be used for them
Advantages and limitations of FECPAK
Ad= Does not require technical skills as eggs identified and counted remotely, digitalised images
Lim= Low accuracy, precision and medium sensitivity, time-consuming
What is the FEC reduction test used for?
Detection of anthelmintic resistance
Describe how you do a FEC reduction test
FEC on 2 faecal samples
- 1 at the time of treatment
- 1 at defined times after treatment (dependent on drug used 3-17 days)
What is a mathematical equation for McMaster egg counting? (measures number of eggs in faeces)
Number of eggs in faeces = Number of eggs counted x total volume (ml) / Volume of counted chamber (l) x weight of faeces (g)
Describe the direct smear method of FEC
a small amount of faeces miked with saline on a microscope slide
Describe the cornell-wisconsin method of FEC
Centrifugal flotation of eggs in a salt solution in a tube, and collection onto a coverslip and counting under a microscope
What is the cut off number where FEC resistance is assumed
<95%
