Module 3: The Quantitative Fecal Exam
Module 3.2: The McMaster’s and Wisconsin Techniques
The McMaster’s and Wisconsin techniques
The McMaster’s and Wisconsin techniques are both quantitative tests but do have some differences that are outlined in the chart below. Please refer to pages 10-12 in your parasite lab manual for specific laboratory methods.
Modified McMaster’s |
Wisconsin |
|
|---|---|---|
Sensitivity |
within 25-50 epg | within <1 epg |
When would you choose this test? |
Expected egg numbers are >100 epg | Expected egg numbers are <100 epg |
Method |
The flotation is a dilution technique and requires a special reusable slide (McMaster’s slide) with a grid and two chambers. Only eggs that are found in the grids are counted and applied to an equation to determine epg | Double centrifugal float technique using a known amount of feces. All eggs under the coverslip are counted to determine epg. This is not a dilution technique. |
Flotation solution |
Depends, often Sheather’s Sugar Solution | Depends, often Sheather’s Sugar Solution |
Preferred technique? |
The technique of choice for quantifying protozoan ova or when an animal is heavily infected with parasites because it is a dilutional technique. | The technique of choice for quantifying helminth ova or when you expect that an animal has a low parasite burden. |
