Does your mystery organism have parasites?You will preform a floatation test to determine if feces obtained from an unidentified organism contains tapeworm eggs. The tapeworm in question is Hymenolepis diminuta. In mammals it is usually asymptomatic. It can cause abdominal pain, irritability, and itching. Because it is usually asymptomatic and only causes in humans few side effects in extreme cases, it had been considered as a possible candidate for helminthic therapy. This is a practice gaining popularity in which helminthes (basically nematodes or flatworm parasites) are fed to humans that have life threatening autoimmune disease. The reasons this treatment works , are still debated, but in most cases the symptoms of the autoimmune disease are dramatically reduced.

These eggs are living but must past through a beetle to develop into larvae that can infect mammals. To become infected you would have to feed the eggs you find to a insect, such as a beetle, and then eat the beetles. The rare cases of human infection involve children eating infected cockroaches that ate H. dimunuta eggs from rats in rural overpopulated areas of the world. Nevertheless, you are to wear gloves through the procedure. The entire laboratory conducts the procedure at one time and everything you use should be wiped down with alcohol and disposed of immediately after this activity. We will freeze and then microwave anything used to kill any living eggs remaining. So please keep cleaning supplies to a minimum. We have as a precaution, already kept these eggs well past their due date for being infectious. Luckily for us, even dead eggs will float to the surface of a sucrose solution of proper density.

Examinations of feces for parasite eggs is often difficult. This is the perfect textbook image given to technicians to match eggs found. Often these images are taken at 400 to 1000x.

Unfortunately eggs are more difficult to identify when examined under the microscope at 40-100x magnification. Solutions of fecal material are crowded with debris and murky.

The bottom photograph contains a number of eggs. Can you find any?

Veterinarians often rely on floatation test where eggs will rise and adhere to a floating coverslip in solutions of proper specific gravity.

Activity: Obtain a small sample of feces, no more than the tip of a spatula worth (about ½ of a dime or a small marble’s worth). Mix with 10 milliliters of floatation solution, breaking up any large clumps, trying to get a uniform mixture. Pour the solution, through a two layer cheesecloth filter, into a sucrose solution of 1.24 specific density (124%). There should be plastic test tubes available that are ¼ to ½ full of the sucrose solution. Mix gently.

Pour more sucrose solution until the test tube is filled to the top (Just about to overflow) with sucrose solution. Place a coverslip on the surface of the solution and leave for at least 10 minutes. Examine the coverslip, (slip side floating on solution side up) under the highest power under the stereoscope. Photograph your results. Clean stage with towel and alcohol after use.

This photograph below has been run through color and sharpened filters to allow you to at least see the 4 large eggs that catch the light just right. There are actually at least 20 more smaller eggs (actually less distorted) that blend into the background, that may not be caught in microscopic analyses but will float to the surface in a solution of proper specific gravity.

Don’t believe us, examine this sharpened image of a slightly magnified view (100x) of a small section of the photo above. You should see three (four if look closely at edge) more eggs.

Compare the visibility of these to those of your eggs isolated by flotation in your journal.