Modified Wisconsin Sugar Flotation Method

This method of determining the EPG is probably the most commonly used method. First used by the University of Wisconsin's Parasitology Laboratory, it is a modification of the Stoll technique. It is the most accurate as it counts all the eggs in 3 grams of feces and, because it is a flotation method, it has little debris to interfere with the count. However, if the EPG is high, there may be too many eggs to count.

1. Fill a 15 ml test tube with 10 ml of Sheather's solution.
2. Weigh 3 grams of feces and place into a cup.
3. Pour the Sheather's solution from the test tube into the cup and mix well.
4. Place a funnel into the test tube tube, place a strainer into the funnel and pour the fecal-sugar solution mixture through the strainer into the test tube. Using a tongue depressor, squeeze the liquid out of the feces that is left in the strainer.
5. Centrifuge the tube for 2 to 4 minutes.
6. Fill the tube to just over the top with Sheather's solution and place a cover slip onto the meniscus.
7. Let sit for about 5 minutes, then remove the cover slip and place on a slide.
8. Examine the entire cover slip and count the number of eggs that you find.
9. The number of eggs counted is the number per 3 grams of feces, so divide by 3 to find the EPG.

Sheather's Solution Preparation:  Add 454 gm (1 lb) of table sugar to 355 ml of very hot water. Stir until dissolved and allow to cool. This solution will grow mold if left out, so keep refrigerated and use quickly.