1. Medical Parasitology Lab.
Zinc Sulphate method

2. Flotation
The flotation procedure permits the separation of protozoan cysts and certain eggs from excess debris through the use of a liquid with a high specific gravity.
The parasitic elements are recovered in the surface film, and the debris remains in the bottom of the tube.
This technique yields a cleaner preparation than the sedimentation procedure.

3. Zinc Sulphate technique
Advantages:
Zinc sulphate centrifugal flotation technique is useful for the recovery of protozoan cysts and helminthes eggs.
Disadvantages:
Large trematode eggs, some tape worm eggs, and infertile Ascaris lumbricoides eggs are not concentrated by this method.

4. Why can’t all helminth eggs be recovered using the flotation concentration rather than the sedimentation concentration?
Some helminth eggs are quite heavy (unfertilized Ascaris eggs) and will not float, even using zinc sulfate with a specific gravity of Other helminth eggs are operculated; when the egg is placed in a high specific gravity solution, the operculum “pops” open and the egg fills with fluid and sinks to the bottom of the tube. Thus, both the surface film and the sediment should be examined before reporting the specimen as negative.

5. Materials and Method
Zinc sulphate solution with specific gravity 1.18.
Mix 330gm dry zinc sulphate in 670ml distilled water.
Use the hydrometer or densitometer to adjust specific gravity around 1.18
Notes :
Warning! May cause skin irritation. May cause eye irritation and possible burns.
Evaporation Rate:< ether
Chemical Stability: Stable under normal temperatures and pressures.

6. Zinc Sulphate centrifugal flotation technique
Transfer about 0.5 teaspoon of stool to a test tube containing 1-2 ml of water and comminute thoroughly then fill the tube to within 2-3 mm of the top with water.
Centrifuge at 1500 rpm for 1 mint. Discard supernatant fluid.
If the sample contains a large amount of material that floats in water, you may want to wash the sample before doing the flotation.
Add 1-3 ml of zinc sulphate solution to the sediment and resuspend the sediment.
Fill the tube within 2-3 mm of rim with additional zinc sulfate solution.

7. Strain the suspension through strainer into paper cup.
Return the suspension to the tube, and add enough zinc sulfate solution to fill within 2-3mm of rim .
Centrifuge at 1500 rpm for a 1 minute. Allow the centrifuge to come to a stop without interference or vibration.
Without removing the centrifuge tube from the centrifuge and using wire loop ,remove 1-2 drops from the center of the surface film and add them to the drop of iodine or water on the slide then make examination .

9. Notes
The surface film must be examined within a few minutes after flotation is complete. Otherwise the cysts and eggs may distort or collapse.
If zinc sulfate is the only concentration method used, both the surface film and the sediment should be examined should be examined to ensure the detection of all possible organisms.

10. Why is the flotation concentration used less frequently than the sedimentation concentration?
There are several reasons. First, not all parasites will float; therefore, you need to examine both the surface film and the sediment before indicating the concentration examination is negative. Second, the organisms must not be left in contact with the high specific gravity zinc sulfate for too long or protozoa will tend to become distorted, so the timing of the examination is more critical. Also, the specific gravity of the fluid will need to be checked periodically.

11. Cestodes Dog Tape worm – Echinococcus granulosus Fish Tape worm
– Diphylobothrium latum
Beef Tape worm
– Taenia saginata
Pork Tape worm
– Taenia solium
Dwarf Tape worm
– Hymenolepis nana

12. Ecchinococcus granulosus
Tissue Cestodes
Ecchinococcus granulosus

13. Ecchinococcus granulosus also known as hydatid worm.
Disease: Ecchinococcus (serious disease).
Adult lives in intestine of dogs but never in human intestine.
Definitive host: Dogs.
Dead end host: Human.
Intermediate host: sheep, cattle, horse, pigs.
Infective stage: ova by fecal oral route.
Diagnosis:
Tests involve antigen antibody reaction.
X-RAY examination.

14. Ecchinococcus granulosus stages

15. Intestinal Cestodes

16. Diphyllobotherium latum
knows as abroad fish tapeworm which can cause Diphylobotheriasis.
Mode of infection: through consumption of raw or undercooked fish contain plerocercoid larva.
Immature eggs are passed in feces of the mammal host (the definitive host).
After ingestion by a suitable freshwater crustacean (intermediate host), the coracidia develop into procercoid larvae.
Following ingestion of the crustacean by a suitable second intermediate host, the procercoid larvae are released from the crustacean and migrate into the fish's flesh where they develop into a plerocercoid larvae
The plerocercoid larvae are the infective stage for the definitive host (including humans).
Diagnosis:
Stool analysis to finding typical eggs ( oval, yellow brown with operculum at one end) and segments.
The scolex is the head portion of the worm, and is equipped with a slit-like groove (the bothrium) for attachment to the intestine.
Un embryonated egg passed in feces and become embryonated in water

17. Diphyllobotherium latum eggs

18. Taenia spp.

19. Taenia spp Both have mature, immature and gravid segments.
Of the 32 recognized species of Taenia, only Taenia solium and Taenia saginata are medically important.
Taenia saginata, which is also known as the "beef tapeworm", though it also infects humans.
Taenia solium, which is known as the "pork tapeworm". Like Taenia saginata humans serve as its primary host.
Both have mature, immature and gravid segments.
Both have scolex provided with four cup- shaped suckers, but T. saginata has an unarmed scolex while T. solium has an armed scolex

20. In both species the infective stage is the cysticercus.
Cows are the intermediate host of T. saginata while pigs are the intermediate host of T. solium.
Definitive host: Human.
Diagnosis:
By finding gravid proglotid or eggs in stool.
Eggs present in stool less often are proglottids.
Direct fecal smear.
Brine flotation technique.
Taenia saginata and Taenia solium must be differentiated from each other by the following:
Mature segment, gravid proglotid and adult worm.

21. Taenia Egg

22. Taenia scolex
Taenia saginata
Taenia solium

23. Taenia mature segment Taenia saginata 2 ovary lobes Taenia solium

24. Taenia Gravid Proglotid
Taenia saginata
Taenia solium

25. Taenia Adult worm
Taenia saginata
Taenia solium

26. Comparison Aspect Taenia saginata Taenia solium Intermediate host Cows
(Beef tape worm)
Pigs
(Pork tape worm)
Adult size
Longer ( 4 – 8 meters )
Smaller ( meters )
Number of segment
1000 – 2000
Mature segment
2 lobes ovary
3 lobes ovary
Gravid proglotid
With 15 – 30 uterine branches
With 7 – 13 uterine branches
Scolex
Devoid rostellum and hooks
With rostellum and 2 rows of hooks
Larvae
Cysticercus bovis in cattle only
Cysticercus cellulosae in pig as well as in man
Disease caused in man
Taeniasis
Taeniasis and cysticercosis
Comparison
Raed Z. Ahmed, Medical Parasitology Lab.,2012

27. Hymenolepis nana
This is one of the most common cestodes of humans, especially children. And it’s the smallest tape worm in man, also called dwarf tape worm.
Eggs measures 30-37u, and have double membrane and contain six hooked oncosphere.
The scolex of  H. nana has four suckers and a short rostellum with hooks.
Infective stage: Eggs.
Diagnosis:
Stool examination to detect the eggs.

28. H. nana egg

29. Hymenolepis nana – The Dwarf Tapeworm

30. Hymenolepis nana (Dwarf Tape Worm) Definitive host Man
Intermediate host No
Infective form
Eggs
Internal autoinfection
Mode of transmission
Ingestion
Site of localization
Small intestine

31. Hymenolepis nana scolex

32. Mature proglottid

33. Gravid proglottid