Trematodes.pptx trematodes detail explanation

trematodes

1. Introduction to Trematodes (flukes) Subclass Digenea

2. Outline General characteristics of trematodes General morphology Attachment organ Digestive tract General life cycle and reproduction of trematodes General feature of the different stage of trematode Classification of trematodes

3. Learning objective At the end of this section the student will be able to Explain the general feature of trematodes Describe the general morphology of the different stage of trematodes Explain the general reproduction and life cycle of trematode Explain the general feature of the different stage of the trematode Classify and list medically important trematodes

4. General characterístis Are generally flat, unsegmented , leaf shaped worms ( exception, schistosomes - cylindrical)

5. Vary in size from species just visible to the naked eye to large fleshy species,

6. Attachment organ Characteristics- 2 suckers Muscular oral sucker surrounding mouth at anterior end One or more suckers on ventral surface (called “ ventral sucker ,” “ posterior sucker ,” or acetabulum .” Morphology

7. Characteristics- 2 suckers Muscular oral sucker ventral sucker , Attachment organ

8. Digestive tract Digestive tract consists of mouth and esophagus divides to “ “shaped. Vitellaria – yolk and eggshell producing organs connected to ovaries. Y

9. Reproduction Sex organs - Most adult digenetic trematodes are monoecious (a single organism contains both male (blue) and female (orange) reproductive organs) Schistosomes.;dieces (separate sex)

10. General Life Cycle Are digenetic (Require at least two hosts) Have sexual and asexual generations Adults are endoparasites of vertebrates First intermediate host = a mollusc

11. General Life Cycle Sexually mature Adult in DF host Eggs in Feces Miracidium Released in H 2 O Miracidium Infects Snail Sporocyst-rediae-cercaria Cercaria Released in H 2 O Infect Definitive Host Directly Infect Secondary Host, develop into Metacercaria which are later, Consumed by Definitive host Intermediate host Definitive host

12. Miracidium : Free living, ciliated larva seeks the intermediate host Sporocyst : Loses larval characteristics, grows in the blood of molluscs and produces germ balls Redia : Sporocyct develops into active, feeding larval stage with the germballs Cercaria : Free swimming larva that leaves the mollusc and enters the definitive host where it develops into an adult Metacercaria : Encycted (waiting) stage in second intermediate host until it is eaten by the definitive host, where it develops into an adult

13. Stages of Trematode Life Cycle Ova or egg Contains miracidium inside shell Usually have an operculum or spine Eggs must be passed out of host May pass in feces either with miracidium developed with only a morula present Many of flukes have very distinctive eggs.

14. Stages of Trematode Life Cycle Miracidium small ciliated, swimming form that hatches from egg May be fully developed when passed or develop outside of host May hatch in water and seek snail and penetrate snail In this case, it contains penetration glands that release histolytic or proteolytic enzymes to help penetrate snail In some species do not hatch until eaten by snail host. In these the miracidium is not as prominent.

15. Stages of Trematode Life Cycle Sporocyst The miracidium develops into sporocyst often in the digestive gland of the snail. The sporocyst is an embryonic bag or germinal sac that has asexual reproduction occurring. The sporocyst will produce many daughter stages called rediae or in some cases daughter sporocysts. The term daughter has nothing to do with gender.

16. Stages of Trematode Life Cycle Rediae Larval stage in snail with precursor gut and oral sucker Contains germ balls Some germ balls asexually reproduce to yield more of the same (daughter rediae) and others transform into next larval stage ( cercariae) Some species they can live for many years.

17. Stages of Trematode Life Cycle Cercariae Infective swimming stage that develops in mollusk Leave the snail to find next host to penetrate or to encyst in or on another host or a substrate to be eaten by final host These usually die within 24 hours of release if not in proper place Variety of tail morphologies

18. Furcocercus (forked tail as in Schistosomes species ), Microcercus (short stumpy and rudimentary tail as in Paragonimus westermani ), Lophocercus ( large fluted tail as in Clonorichis, Heterophyes, Fasciola, Fasciolobsis, Metagonimus) and Pleurolophocercus (long tail with fin folds as in Opisthorchis )

19. Stages of Trematode Life Cycle Metacercaria This larval stage is the endstage cercaria, tail is shed, and the juvenile fluke is within a resistant wall secreted by the fluke Cercaria that have this stage contain cystogenic glands that helps the organism encyst on vegetation. Cercaria that form metacercaria in second intermediate hosts, often have penetration glands that enable them to penetrate the second intermediate host.

20. Stages of Trematode Life Cycle Adult Always found in the definitive host Responsible for sexual reproduction Often restricted to specific region of host. Often very host specific.

21. Classifications Based on their reproductive systems. divided into two major categories The hermaphrodites flukes. The S chistosomes - separate sexes .

22. Based on their habitat. Liver fluke. F. hepatica F. gigantica C vivereni O. sinensis Intestinal fluke F buski H. hetrophyes M. yokogawi Lung fluke P westermani Blood fluke S. mansoni S. hematobium S. japonicum S. intrecalatum S. mekongi