Schistosoma Life Cycle and Treatment
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Schistosomiasis - Parasitology - trematodes -SECOND MBBS STUDENTS - UNDERGRADUATE STUDENTS - MEDICAL COLLEGE - POWERPOINT
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Schistosoma Life Cycle and Treatment
- 1. Schistosoma Dr. R. Someshwaran, MD., Assistant professor, Department of Microbiology, Karpagam faculty of Medical Sciences & Research
- 2. Objective of today’s class • To define the General features, Species and life cycle of Genus Schistosoma • To elucidate briefly on the clinical spectrum, lab diagnosis and management of Schistosomiasis.
- 3. INTRODUCTION • Genus Schistosoma a)Schistosoma hematobium b)Schistosoma japonicum c)Schistosoma mansoni d)Schistosoma intercalatum e)Schistosoma mekongi
- 4. Unlike trematodes Schistosoma has only one intermediate host. No reservoir. Schistosoma eggs bile stained and not operculated . Forked tail cercaria (Infective form). Cylindrical worm (Not flat – leaf like). Only trematode in which sex is separated while other trematodes are hermaphrodite (Monoecious)
- 5. INTRODUCTION • Geographic distributions: • Schistosoma hematobium - Africa, • Schistosoma mansoni - Africa and America • Schistosoma japonicum - Far East Asia, Some parts of Africa • Epidemiology Approximately 250 million people are infected with schistosomes and 600 million are at risk.
- 7. Name:Name: Schistosoma haematobium Schistosoma mansoni Definition:Definition: Blood Flukes (Bilharzia) Distribution:Distribution: Egypt, Africa & middle east Africa, Latin America & portirico. Disease:Disease: Urinary Schistosomiasis Intestinal Schistosomiasis
- 8. Morphology • Adult worms are 10 to 20 mm long • Schistosomes have separate sexes • the male has a canal in which the slender female worm resides
- 9. The eggs are very characteristic and confirm diagnosis. • S. mansoni eggs in feces have a spine on the side • S. hematobium eggs in urine have an apical spine • S. japonicum eggs are more round with a vague spine on the side.
- 10. Schistosoma haematobium Schistosoma mansoni DiagnosticDiagnostic Stage:Stage: Eggs in urine Eggs in stool Infective Stage:Infective Stage: Forked tailed Cercaria swimming in fresh water Mode ofMode of infection:infection: • Cercaria penetrates human skin upon exposure to fresh water containing cercaria & cause itching at site of penetration. • After 2-3 weeks of infection, fever, chills and diarrhoea occurs due to presence of the Schistosoma larva in blood, which migrate to the liver venules.
- 11. Continue No damage in hepatocytes
- 12. LIFE CYCLE
- 13. • Definitive host for Schistosoma spp., is Man • Dogs, cats, rodents, pigs, hourse and goats, serve as Reservoir host for S. Japonicum
- 14. The cercariae • Man is infected by fork tailed cercaria in fresh water by skin penetration • The cercaria travel through the venous circulation to the heart, lungs and portal circulation • They mature and reach: • the mesenteric veins (S. japonicum and S. mansoni) • The bladder vessels (S. hematobium) where they live and ovulate for the duration of the host's life.
- 15. Infective Stage Schistosoma cercaria (forked tail). Found in fresh water. Penetrate the skin of human upon contact with water containing it.
- 16. Intermediate host Schistosoma haematobium Bulinus truncatus Schistosoma mansoni Biomphlaria alexandria
- 17. Sites for localization • S. japonicum - Superior mesenteric veins draining the small intestine • S. Mansoni - Superior mesenteric veins draining the large intestine • S. Haematobium - Venous plexus of bladder, it can also be found in the rectal venules
- 18. Adult worm
- 20. Continue
- 21. Continue
- 22. Schistosoma haematobium eggs in section of bladder Schistosoma mansoni eggs in the wall of the gut
- 24. EGGS
- 26. Schistosoma eggs
- 27. Pathology of schistosomiasis • S. mansoni and S. japonicum includes: • Katayama fever, periportal fibrosis, portal hypertension, and embolic egg granulomas in brain or spinal cord. • S. haematobium includes: hematuria, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord.
- 28. Pathology of Schistosomiasis • Schistosoma haematobium Causes urinary schistosomiasis 1. PREPATENT PERIOD 10-12 wks 2. EGG DEPOSITION AND EXTRUSION: 1. painless haematuria 2. Inflammation of bladder and burning micturition 3. TISSUE PROLIFERATION AND REPAIR: • Fibrosis , papillomata in the bladder and lower ureter leading to obstructive uropathy. • Periportal fibrosis • Lung and CNS involvement • Schistosoma mansoni Causes intestinal schistosomiasis 1. PREPATENT PERIOD 5-7 wks 2. EGG DEPOSITION AND EXTRUSION: 1. dysentery (blood and mucus in stools), 2. hepatomegaly splenomegaly 3. TISSUE PROLIFERATION AND REPAIR:Fibrosis , • Papillomata in intestine, • Pperiportal fibrosis,hematemesis • Lung and CNS involvement.
- 29. Schistosomiasis or bilharzia • Disease affecting many people in developing countries. • ‘Acute schistosomiasis’ - snail fever and cutaneous schistosomiasis. • Low mortality rate, schistosomiasis can also be very debilitating. • Bilharzia, or bilharziosis, is named after Theodor Bilharz, who first described the cause of urinary schistosomiasis in 1851.
- 30. A 13-year-old boy with schistosomiasis • Hepatosplenomegaly, • ascites, • muscle atrophy, • anaemia, • diarrhea • haemorrhage from the gastrointestinal tract
- 31. LAB DIAGNOSIS • Stool, urine samples • Bile stained eggs in stool • Schistosoma hamtobium – Terminal spine • Schistosoma mansoni – Lateral spine • Schistosoma japonicum – Lateral knob
- 32. Diagnostic Stage Schistosoma haematobium :- - Eggs found in urine of urinary Schistosomiasis patients. - Oval egg with terminal spine.
- 33. Diagnostic Stage * Schistosoma mansoni:- - Eggs found in stool of intestinal Schistosomiasis patients. - Oval egg with lateral spine.
- 35. Management • Contaminated water should be avoided • Sanitary disposal of sewage • Prevent the contamination of water by feces and urine • Destruction of snails • Treat the patients • No vaccine is available • Praziquantel is effective against all species
- 36. Schistosoma haematobium Schistosoma mansoni Treatment:Treatment: Praziquantel (Distocide® ,Biltricide®) & Metrifonate Prevention:Prevention: Proper disposal of human sewage and elimination of snail hosts. Continue
- 37. Drugs used in elimination of worms (Praziquantel) Drug of choice for all Trematodes & Cestodes except Fasciola species & hydated sand. The nervous system of Trematodes and Cestodes is not completely studied. However Praziquantel was found to increase the calcium ion influx inside the worm muscle causing prolonged spasms for the worm; leading to spastic paralysis & death of the worm. This action not observed on Nematodes, insects or mammalians.
- 38. Take home message • Schistosoma – Blood flukes • Fork tailed cercaria – Infective form • Not metacercariae unlike Typical trematodes • Bile stained eggs • Schistosoma hamtobium – Terminal spine • Schistosoma mansoni – Lateral spine • Schistosoma japonicum – Lateral knob • Biharrziasis – Treat with Praziquantel
- 39. THANK YOU
Editor's Notes
- the male has an unusual lamelliform shape with marginal folds forming a canal in which the slender female worm resides.
- Diagnosis is based on a history of residence in an endemic area, swimmers' itch and other symptoms. The eggs are moved progressively toward the lumen of the intestine (S. mansoni and S. japonicum) and of the bladder and ureters (S. haematobium), and are eliminated with feces or urine, respectively.
- Cercaria penetrates human skin upon exposure to fresh water containing cercaria. It causes itching at site of penetration. After 2-3 weeks of infection, fever, chills and diarrhoea occurs due to presence of the Schistosoma larva in blood, which migrate to the liver venules.
- Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, hourse and goats, serve as reservoirs for S. Japonicum.
- the infective cercariae swim, penetrate the skin of the human host, and shed their forked tail, becoming schistosomulae.
- The symptoms of schistosomiasis are primarily due to a reaction against the eggs and include splenomegaly, lymphadenopathy and diarrhea. In the bladder, they produce granulomatous lesions, hematuria and sometimes urethral occlusion. Most bladder cancers in endemic areas are associated with chronic infection. In the intestine
- Cercaria penetrates human skin upon exposure to fresh water containing cercaria. It causes itching at site of penetration. After 2-3 weeks of infection, fever, chills and diarrhoea occurs due to presence of the Schistosoma larva in blood, which migrate to the liver venules.