Stolls method Counting helminthes eggs in feces The

Stoll’s method

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. , 2012

Stool’s technique procedures 1. 2. 3. 4. 5. 6. 7. 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. 1 mol/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 10 x 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. , 2012

Continue ………… 8. 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 9. Calculate the number of eggs per day, by multiplying the number of eggs per gram by the total weight of 24 hrs fecal specimen. 10. 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. , 2012

Interpretation of result The Center For Disease Control, Atlanta Protozoa Helminthes Rare 2 -5 / coverslip Few 1 / 5 -10 HPF 1 -2 / LPF 1 -2/ HPF or 1/ 2 -3 HPF 1 / 5 -10 HPF Several / LPF Moderate Many Raed Z. Ahmed, Medical Parasitology Lab. , 2012

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

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 – 15 -30 cm in length. • Female: oviparous have straight, pointed tail and no spicules. (lay 200, 000 eggs daily) – 20 -40 cm in length. • Infective stage: Embryonated eggs. Raed Z. Ahmed, Medical Parasitology Lab. , 2012

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 • Corticated and Decorticated – Unfertilized egg • Corticated and Decorticated Raed Z. Ahmed, Medical Parasitology Lab. , 2012

Ascaris lumbricoides Adult Raed Z. Ahmed, Medical Parasitology Lab. , 2012

Ascaris lumbricoides Unfertilized Egg Corticated Decorticated Raed Z. Ahmed, Medical Parasitology Lab. , 2012

Ascaris lumbricoides Fertilized Egg Corticated Decorticated Raed Z. Ahmed, Medical Parasitology Lab. , 2012

Ascaris lumbricoides Embryonated Egg Corticated Decorticated Raed Z. Ahmed, Medical Parasitology Lab. , 2012

Ascaris Lumbricoides Larvae Raed Z. Ahmed, Medical Parasitology Lab. , 2012