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Schistosomiasis Miracidia produces enzymes and secretions while in the egg.Miracidia produces enzymes and secretions while in the egg. Ag/Ab reaction to.

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Presentation on theme: "Schistosomiasis Miracidia produces enzymes and secretions while in the egg.Miracidia produces enzymes and secretions while in the egg. Ag/Ab reaction to."— Presentation transcript:

1 Schistosomiasis Miracidia produces enzymes and secretions while in the egg.Miracidia produces enzymes and secretions while in the egg. Ag/Ab reaction to miracidial secretions through egg, resulting in egg granuloma the Hoeppli phenomenon!Ag/Ab reaction to miracidial secretions through egg, resulting in egg granuloma the Hoeppli phenomenon! Ag/Ab

2 How many eggs make it to the lumen? 2/3 of those that enter tissue do not leave.2/3 of those that enter tissue do not leave. Many eggs do not enter tissueMany eggs do not enter tissue –Swept away in blood stream –Liver and spleen are first organs –Then Lungs –Other organs –Eggs look like Psuedotubercles 100, 000 eggs/gram!

3 1.Migratory Phase Penetration to Egg productionPenetration to Egg production SymptomlessSymptomless Dermal rashDermal rash Pathology and Symptoms

4 2. Acute Phase Egg ProductionEgg Production Chills, fever, fatigue, headache, malaiseChills, fever, fatigue, headache, malaise Much exposure to antigensMuch exposure to antigens Granulomas surround eggsGranulomas surround eggs Eosinophils, neutrophils, macrophagesEosinophils, neutrophils, macrophages 1-2 weeks fibroblasts enter granuloma1-2 weeks fibroblasts enter granuloma Psuedotubercles-fibrous granulomasPsuedotubercles-fibrous granulomas Pathology and Symptoms

5 3. Chronic Phase AsymptomaticAsymptomatic S. haematobiumS. haematobium –Blood in the urine –Pain with urination –Loss of bladder function –Bladder cancer? –Eggs dont metastasize?

6 Pathology and Symptoms 3. Chronic Phase S. japonicum, S. mansoniS. japonicum, S. mansoni –Mild, chronic dysentery –Abdominal pain –8% infections develop liver fibrosis that impedes blood flow –Cirrhosis of liver Long term problemsLong term problems –Hepatosplenomeagly Long term: loss of tissue functionLong term: loss of tissue function

7 Ascites

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9 Schistosoma japonicum Anterior mesenteric veinsAnterior mesenteric veins Small intestineSmall intestine Interfere with absorptionInterfere with absorption –Stunting Eggs can go to brainEggs can go to brain –Smaller –Brain lesions 25 year old

10 Pathology Adults cause no pathologyAdults cause no pathology –hide from immune system –Absorb host antigens Pathology due to eggsPathology due to eggs

11 Diagnosis Schistosoma mansoni and S. japonicum?Schistosoma mansoni and S. japonicum? Schistosoma haematobium?Schistosoma haematobium? Small number of eggsSmall number of eggs SerodiagnosisSerodiagnosis

12 Treatment PraziquantelPraziquantel PrognosisPrognosis –Effective –Much of fibrosis can be reversed –Severe damage irreversible

13 Epidemiology How do you get infected with a species of Schistosoma?How do you get infected with a species of Schistosoma?

14 Epidemiology What causes people to come into contact with water?What causes people to come into contact with water?

15 Work: Fisherman, agricultural workers, housework

16 Bathing and Play

17 Traditions AblutionAblution

18 How do eggs get into water supply?

19 What else do you need?

20 Snails Schistosoma mansoniSchistosoma mansoni –Biomphilaria glabrata Schistosoma japonicumSchistosoma japonicum –Oncomelania Schistosoma heamatobiumSchistosoma heamatobium –Bulinus

21 Snail Habitat Any freshwaterAny freshwater Eutrophic bodies of waterEutrophic bodies of water Shallow areas near shoreShallow areas near shore Associated withAssociated with –Aquatic plants –Decaying organic debris

22 Transmission can occur only during certain seasonsTransmission can occur only during certain seasons Snail abundanceSnail abundance Dry seasonDry season –Some species burrow into mud Seasonal Transmission

23 Human Manipulations Agricultural projectsAgricultural projects –Improve agriculture Unintended consequencesUnintended consequences –Increase snail habitat –Zimbabwe: $10 million irrigation project abandoned –Aswan High Dam in Egypt

24 Aswan High Dam Increased snail habitatIncreased snail habitat Increased SchistosomiasisIncreased Schistosomiasis –Below dam Varied by significant increasesVaried by significant increases From 5%-35%From 5%-35% –Above dam From 5% in 1968 to 77% in 1993From 5% in 1968 to 77% in 1993

25 Reservoir Hosts Schistosoma haematobiumSchistosoma haematobium –None known Schistosoma mansoniSchistosoma mansoni –Many mammals: monkeys and rodents Schistosoma japonicumSchistosoma japonicum –Least host specific –Many mammals

26 Control Infected People Uninfected People contact Season Habitat Behavior Sewage Occupation Behavior Bathing

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30 # 1 Control How do you get rid of snails?How do you get rid of snails? Remove by handRemove by hand MolluscicideMolluscicide Biological controlBiological control Eliminate habitatEliminate habitat Do these work?Do these work? Too many snailsToo many snails Molluscicides ineffectiveMolluscicides ineffective –Oncomelania Biological control sometimes effectiveBiological control sometimes effective People need water, tooPeople need water, too

31 Control Infected People Uninfected People contact Season Habitat Behavior Sewage Occupation Behavior Bathing

32 #2 Control How do you prevent eggs from contaminating water supplies?How do you prevent eggs from contaminating water supplies? Sewage treatmentSewage treatment Eliminate night soilEliminate night soil EducationEducation Why doesnt this work?Why doesnt this work? ExpensiveExpensive Reservoir hostsReservoir hosts

33 Control Infected People Uninfected People contact Season Habitat Behavior Sewage Occupation Behavior Bathing

34 # 3 Control How do you prevent people from contacting cercariae?How do you prevent people from contacting cercariae? EducationEducation Protective gear (waders, boots)Protective gear (waders, boots) Provide non-contaminated waterProvide non-contaminated water VaccinesVaccines Why dont these methods work?Why dont these methods work? People need waterPeople need water Fishermen, Agricultural workers cant avoidFishermen, Agricultural workers cant avoid –60% world calories from rice Protective gear hot and cumbersomeProtective gear hot and cumbersome AblutionAblution Cost of clean waterCost of clean water Vaccines unsuccessfulVaccines unsuccessful

35 Control Infected People Uninfected People contact Season Habitat Behavior Sewage Occupation Behavior Bathing

36 # 4 Control How can you eliminate the parasite?How can you eliminate the parasite? Drug treatmentDrug treatment Genetically modified snailsGenetically modified snails Do these work?Do these work? CostCost –Dose of praziquantel = $0.20 No genetically modified snails yetNo genetically modified snails yet

37 Cercarial Dermatitis/ Swimmers Itch 10 species (U.S.)10 species (U.S.)

38 Trichobilharzia sp.

39 Matts leg with cercarial dermatitis or swimmerss itch caused by cercariae of avian blood flukes.

40 Furcocercous cercariae diagnostic for Schistosomes.

41 Cercarial Dermatitis/ Swimmers Itch Inflammatory responseInflammatory response Pus-filled pimplesPus-filled pimples Itching and painItching and pain 4 days4 days

42 Dendritobilharzia spp. Live in the dorsal aorta of ducks!Live in the dorsal aorta of ducks!

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44 Ducks can infect snails that can infect swans!

45 Eggs can enter CNS via arterial circulation causing CNS disease!


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