Chapter 4 Trematodes (blood Flukes).pptx

Poisson distribution ppt

1. 1 Section: 3 – Trematodes (Flukes)

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 2

3. Class Trematoda Trematode parasites of man belong to Order Digenea Characters: Flattened dorsoventrally / leaf like (Schistosomes – cylinderical) Bilaterally symmetrical Unsegmented Has no body cavity Cuticle covered with spines (help in fixation) Organs of fixation in the form of suckers 3

4. Vary in size from visible ( Heterophyes ) to large fleshy ( Fasciolopsis . ) Morphology 4 Schistosomes

5. 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.” General characteristics cont’d …

6. Digestive tract Digestive tract consists of mouth and esophagus divides to “ “shaped. Y General characteristics cont’d …

7. Reproduction Sex organs - Most adult digenetic trematodes are monoecious ( Hermaphroditic) ( male (orange) & female (blue) Schistosomes: dioecious (separate sex) General characteristics cont’d …

8. Sexes of flukes 8

9. Class Trematoda The life cycle is passed in two hosts (alternation of hosts) and has sexual and asexual stages (alternation of generations = metamorphosis): Final host: harbour the sexual stage of the parasite (adult worm) Man (DH) Other animals (RH) Intermediate host: harbour the asexual stages of the parasite Snail (molluscan host) 9

10. General life cycle 10

11. Sexually mature Adult in DF hosts 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 11 General characteristics cont’d … General Life Cycle

12. Ova or egg Many of flukes have very distinctive eggs. Schistosomes produce non-operculated eggs With miracidium developed inside shell Hermaphroditic trematodes produce operculated with only a morula present when pass 12 Stages of Trematode Life Cycle

13. 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 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. 13 Stages of Trematode cont’d…

14. 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 . 14 Stages of Trematode cont’d…

15. Rediae Larval stage in snail & contains germ balls Some germ balls asexually reproduce to yield more of the same (daughter rediae ) & Others transform into next larval stage ( cercariae ) Some species they can live for many years. 15 Stages of Trematode cont’d…

16. Cercariae Infective swimming stage that develops in mollusk Leave the snail to find next host to penetrate or to encyst in/on or a substrate to be eaten by final host These usually die within 24 hours of release if not in proper place 16 Stages of Trematode cont’d…

17. Metacercaria The end stage cercaria , tail is shed & the juvenile fluke is within a resistant wall secreted by the fluke Contain cystogenic glands that helps the organism encyst on vegetation. Often have penetration glands that enable them to penetrate the second intermediate host. 17 Stages of Trematode cont’d…

18. Adult Always found in the definitive host Responsible for sexual reproduction Often restricted to specific region of host. Often very host specific Classification of trematodes Based on their reproductive systems The hermaphroditic flukes or monocious ( other tissue flukes ) The dioecious or separate sexes: S chistosomes ( blood flukes ) 18 General characteristics cont’d …

19. Based on their Habitat Blood fluke: S. mansoni, S. hematobium , S. japonicum, S. intrecalatum , S. mekongi Liver fluke: Fasciola spp. (F. hepatica, F. gigantica ), Clonorchis sinensis , Opisthorchis felineus & O. viverrini Intestinal fluke: Fasciolopsis buski , Heterophyes heterophyes & Metagonimus yokogawai Lung fluke: Paragonimus westermani 19

20. Cont… The trematodes that infect liver, lung, and intestine are all food-borne. Freshwater fish, crustaceans, and aquatic vegetation are the sources of human infection. 20

21. Blood flukes (Schistosomes) General feature: Develop in the portal venous system The adult live in the veins that drain the intestine or the urinary bladder (species dependent) Sexes are separate (Diecious - bisexual) Cylinderical No redia and metacercaria stages 21

22. Blood flukes (Schistosomes) Males broader & females filiform and larger than male Male has gynaecophoric canal where the female resides after mating Freshwater snails serve as Ihs, no 2 IH Humans the most significant DHs, cercaria is the infective stage The immature stage that migrates in the body after infection by cercaria is called schistosomulum 22

23. Cont… The female is usually found within this canal “safe in the arms of her lover.” She leaves only during the egg laying period. Males are broader and females are filiform and larger than male 23

24. Blood flukes (Schistosomes) Schistosomiasis is caused by digenetic blood trematodes.  The three main species infecting humans are Schistosoma haematobium , S. japonicum , and S. mansoni .  Two other species, more localized geographically, are S. mekongi( Southeast Asia ) and S. intercalatum ( central West Africa ).  In addition, other species of schistosomes, which parasitize birds and mammals, can cause cercarial dermatitis in humans. 24

25. Blood flukes (Schistosomes) Adult worms reside in venous system S. haematobium resides in veins of urinary bladder S. japonicum in superior mesenteric veins of small intestine S. mansoni in inferior mesenteric veins of large intestine worms move upstream to smaller venules to lay eggs Eggs traverse tissue to exit in gut or bladder 25

26. Humans are the only or most significant host for most spps Snail host is required as intermediate host There are no second intermediate hosts Reproduction takes in the sporocyst stage in the snail. Cercaria is the infective stage to humans in water and t he infective route is by skin penetration Egg without operculum, but with spine & are diagnostic stages 26 Schistosomes cont’d…

27. Transmissions and life cycles 27

28. 28 Schistosomes cont’d… Biomphalaria Oncomelania bulinus S . mansoni S. japonicum S. hematobium

29. Clinical features of intestinal schistosomiasis Penetration of skin : Penetration of skin by cercariae causes transient dermatitis known as “swimmers ' itch” Migratory phase : 4-10 weeks after infection. Is characterized by fever and toxic or allergic reactions resulting from migration of immature organisms. Often results in bronchitis, hepatomegaly, splenomegaly, & diarrhea. 29 Schistosomes cont’d…

30. Chronic phase persons in endemic regions are asymptomatic but may have mild, chronic bloody stools or urine . Often have formation of granulomas, Spleenomegaly , Ascites (accumulation of fluid in abdominal cavity), Hepatomegaly Portal vein hypertension syndrome, abdomen distention looks like a big drum Ectopic lesion : The damage to the CNS (brain, spinal) may cause paralysis ( monoplegia,hemiplegia ) 30 Schistosomes cont’d…

31. Urinary schistosomiasis Due to Schistosoma hematobium Clinical presentations: Hematuria, urinary frequency, pyuria , pyelonephritis, Obstractive uropathy , cancer of bladder, Distant metastases, pulmonary hypertension 31 Schistosomes cont’d…

32. Laboratory diagnosis Intestinal schistosomiasis Finding eggs in feces by direct examination or concentration ( formol -ether concentration, Kato- katz technique Mucus and blood often in feces Examining rectal biopsy, occasionally in urine (contamination) Antigen-Antibody detection techniques: helpful in pre-patent period, chronic, ectopic cases, eggs can’t seen in feces ELISA, RIA, Latex agglutination, detect circulating Ag/Ab 32 Schistosomes cont’d…

33. Egg: S. mansoni Size : 114-17µm by 45-68µm Shell : smooth, very thin Colour : pale yellow-brown Shape : Oval, one well rounded pole & one more conical pole Spine : large, triangular lateral spine near the rounded end Content : fully embryonated (developed miracidium ) when discharged with the feces 33 Schistosomes cont’d…

34. Egg: S. japonicum Size : 70-80  m Shape : oval, almost round Colour : transparent or pale-yellow Spine : very small hook-like knob laterally Contain a fully developed miracidium 34 Schistosomes cont’d…

35. Urinary schistosomiasis Finding eggs or occasionally the hatched miracidia in urine. Quantitative test is required, no of eggs/10ml urine Urine contains blood & appears red or red-brown & cloudy. Hematuria, Protienuria , Eosinophilia Less frequently eggs in feces, rectal biopsy or bladder mucosal biopsy when an infection is light. Immunodiagnosis : RIA, ELISA, IHA. 35 Schistosomes cont’d…

36. Egg: S. hematobium Size : 120 - 170  µm by 40-70µm & Color: pale yellow-brown Shape: oval, with one well rounded pole Spine : Terminal spine at one pole Shell: Smooth, very thin except minute spines on the sucker Shell is not acid fast in ZN staining, but other terminally spined eggs of Schistosoma species are acid fast Contain fully developed miracidium when laid 36 Schistosomes cont’d…

37. Treatment : Praziquantel : effective in a single dose against all species Oxamniquine : effective in a single dose, only for S. mansoni Metrifonate : for schistosoma hematobium Prevention and control Snail control through focal mollusciciding Provision of safe, adequate water supply and sanitation Health information 37 Schistosomes cont’d…

38. Common name : sheep liver fluke Distribution: Cosmopolitan; prevalent in most sheep and cattle raising countries In Ethiopia: Does not play an important role in human health Few reported cases of the disease; eggs in the stools of people who had consumed infected liver of sheep or cattle Causes serious economic loss throughout the highlands by infecting cattle and sheep 38 Liver Flukes – Fasciola hepatica

39. General Features Adults are large and live in the liver or biliary duct Eggs are large and contain undeveloped ovum when passed in the feces   They are hermaphrodite Includes: Fasciola hepatica, Fasciola gigantica , Opisthorchis felineus Opisthorchis sinensis , Opisthorchis viverrini , 39 Fasciola hepatica cont’d….

40. Habitat Adult : In the bile duct of sheep, goat , cattle & man Egg : In feces, All larva stages : Fresh water snail Metacercaria : on water vegetations Morphology Adult: Size: 30 mm X 12 mm, Shape : fleshy, flat, leaf-like, Color : grey brown Cone shaped prominent two “ shoulders” 40 Fasciola hepatica cont’d….

41. Egg Size : 130-150  m by 60-90  m Shape : oval with rounded poles Shell : smooth with a double line & marked operculum at one pole Color : bile-stained or yellow to dark brown 41 Fasciola hepatica cont’d….

42. Life cycle Immature eggs are discharged in the stool Eggs become embryonated in water , eggs release miracidia miracidia invade snail intermediate host : genus Lymnae   miracidia sporocysts rediae cercariae cercariae released from the snail & encyst as m etacercariae on aquatic vegetation   42 Fasciola hepatica cont’d….

43. Mammals acquire the infection by eating vegetation containing metacercariae The metacercariae excyst in the duodenum & migrate through the intestinal wall in to peritoneal cavity Then, they penetrate liver capsule & reach to biliary ducts , where they develop into adults In humans, maturation from metacercariae into adult flukes takes about 3 to 4 months 43 Fasciola hepatica cont’d….

44. Life cycle 44

45. Clinical feature and pathology Light infections are usually asymptomatic In heavy infection Local irritation during migration of the young worms to the liver: Fever, Sweating, abdominal pain In chronic infection: obstructive jaundice, persistent diarrhea, anemia 45 Fasciola hepatica cont’d….

46. Laboratory Diagnosis Serological diagnosis by testing serum for antibodies   Finding Eggs in the faces in chronic infection Several specimen may also needed to detect the egg Concentration techniques ( formol ether): b/c usually few Eggs can also be found in duodenal aspirates & in bile 46 Fasciola hepatica cont’d….

47. If eggs found in human feces, must be confirmed due to a infection or not False Fascioliasis - due to ingestion of animal liver containing fasciola egg & detected in feces Confirmation - keep the patient on liver free diet for three days and repeated examination whether it is true or not Treatment Bithinol or Triclabendazole 47 Fasciola hepatica cont’d….

48. Prevention and Control Avoid eating uncooked water plants Treating infected animals & fencing grazing land infected with metacercariae Identifying & destroying snail hosts & snail habitat Sanitary disposal of feces Treating infected individuals & giving health education 48 Fasciola hepatica cont’d….

49. Read the rest of flukes Liver flukes Fasciola gigantica , Clonorchis sinensis, Opisthorchis viverrini , Opisthorchis felineus Intestinal Flukes Fasciolopsis buski , Heterophyes heterophyes , Metagonimus yokogawai , Gastrodiscoides homines Lung fluke Paragonimus westermani (oriental lung fluke) 49

50. Summary Classify trematodes based on habitat Explain the blood flukes common in Ethiopia Which trematode parasite has a gynecophoral canal? Explain the term hermaphroditic parasites and give examples Discuss the infective stage to definitive and intermediate host, diagnostic stages of trematodes 50

51. Thank you! Medically Important Protozoans & Arthropods to be continued…. 51