1. Medical Parasitology Lab.
Counting of Helminthes Eggs
Prepared By:
Mr. Raed Z. Ahmed
Stoll’s method
Raed Z. Ahmed, Medical Parasitology Lab.,

2. Counting helminthes eggs in feces
The intensity of an intestinal helminthes infection may sometimes be indicated by the concentration of its eggs in feces.
Eggs counts can be value in epidemiological surveys.
The approximate number of eggs per gram of feces can be calculated by using formal ether technique.
When a more accurate count is required the Stoll’s method can be used.
Raed Z. Ahmed, Medical Parasitology Lab.,

3. Stoll’s technique procedures
Weight 3 grams of feces in a screw cap container.
Add 42 ml of water to give (1/15) dilution of the feces.
If the feces are formed specimen, use sodium hydroxide 0.1mol/l solution instead of water.
Using a rod, break up the feces and mix it with the water.
Cap the container and shake hard to complete in mixing.
Using a graduated plastic bulled pipette, or a Pasteur pipette marked to measure the required volume, pick 150 μl of the suspension and transfer this slide.
Cover the slide with long coverslip if available, or two squares coverslips.
Examine systematically the entire preparation, using 10x objective. Include the count any eggs laying outside the edges of the coverslip because these are contained in 150 μl sample.
Raed Z. Ahmed, Medical Parasitology Lab.,

4. Raed Z. Ahmed, Medical Parasitology Lab.,2012-2013
Continue …………
Multiply the number of eggs counted by 100 to give the number of eggs per gram of feces.
If the specimen isn’t formed, the following additional calculation is necessary to give the number of eggs per gram.
Fluid specimen *5
Unformed watery specimen *4
Unformed soft specimen *3
Semiformed specimen *2
Calculate the number of eggs per day, by multiplying the number of eggs per gram by the total weight of 24hrs fecal specimen.
Calculate the number of burden worm by dividing the number of eggs per gram on number of eggs the parasite laying per day.
Raed Z. Ahmed, Medical Parasitology Lab.,

5. Interpretation of result
The Center For Disease Control, Atlanta
Protozoa
Helminthes
Rare
2-5 / coverslip
Few
1 / 5-10 HPF
1-2 / LPF
Moderate
1-2/ HPF or 1/ 2-3 HPF
Many
Several / HPF
Several / LPF
Raed Z. Ahmed, Medical Parasitology Lab.,

6. Raed Z. Ahmed, Medical Parasitology Lab.,2012-2013
Intestinal Nematodes
Ascaris lumbricoides
Raed Z. Ahmed, Medical Parasitology Lab.,

7. Raed Z. Ahmed, Medical Parasitology Lab.,2012-2013

8. Raed Z. Ahmed, Medical Parasitology Lab.,2012-2013
Ascaris lumbricoides
Ascaris lumbricoides is the giant roundworm of human, inhabit small intestine and cause Ascariasis .
There are three diagnostic stages for Ascaris lumbricoides :
Fertilized eggs.
Unfertilized eggs..
Adult:
Male: has a coiled posterior end, 2 minute spicules and no copulatory bursa – cm in length.
Female: oviparous have straight, pointed tail and no spicules. (lay 200,000 eggs daily) – cm in length.
Infective stage: Embryonated eggs.
Raed Z. Ahmed, Medical Parasitology Lab.,

9. Ascaris lumbricoides Ova
Diagnosis:
Stool analysis to detect unfertilized eggs, fertilized eggs or adult.
There are 3 shapes of ova:
Embryonated egg
Corticated and Decorticated
Fertilized egg
Unfertilized egg
Raed Z. Ahmed, Medical Parasitology Lab.,

10. Ascaris lumbricoides Adult
Raed Z. Ahmed, Medical Parasitology Lab.,

11. Ascaris lumbricoides Unfertilized Egg
Corticated
Decorticated
Raed Z. Ahmed, Medical Parasitology Lab.,

12. Ascaris lumbricoides Fertilized Egg
Corticated
Decorticated
Raed Z. Ahmed, Medical Parasitology Lab.,

13. Ascaris lumbricoides Embryonated Egg
Corticated
Decorticated
Raed Z. Ahmed, Medical Parasitology Lab.,

14. Ascaris Lumbricoides Larvae
Raed Z. Ahmed, Medical Parasitology Lab.,