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TREMATODES Faculty: AGUAZIM SAMUEL, M.D.

TREMATODES Faculty: AGUAZIM SAMUEL, M.D. Lange Chapter 55. A 34-year-old Brazilian man presented with a 24-year history of prominent, progressively dilating superficial veins . The veins of the lower limbs dilated first, gradually becoming discolored and indurated (Panel A).

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TREMATODES Faculty: AGUAZIM SAMUEL, M.D.

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  1. TREMATODES Faculty: AGUAZIM SAMUEL, M.D. • Lange Chapter 55

  2. A 34-year-old Brazilian man presented with a 24-year history of prominent, progressively dilating superficial veins. The veins of the lower limbs dilated first, gradually becoming discolored and indurated (Panel A). • After 5 years, varicosities appeared on the anterior chest and abdominal wall (Panel B). Gynecomastia, splenomegaly, and bilateral varicoceles also developed. Jaundice, spider angiomata, and testicular atrophy were not seen. There was no evidence of liver failure; however, a platelet count of 20,000 per cubic millimeter indicated thrombocytopenia. Duplex Doppler ultrasonography of the abdomen showed periportal fibrosis, splenomegaly, and high portal flow. • Esophagogastroduodenoscopy confirmed the presence of esophageal varices. • Viable eggs ofSchistosoma mansoni were found in stool specimens, which confirmed the diagnosis of intestinal schistosomiasis leading to portal hypertension and splenic sequestration. • He was treated with praziquantel and cleared the S. mansoni infection. Despite evidence of profound portal hypertension, he has done well. • More than 200 million people worldwide are infected with schistosomes. Of these, approximately 120 million have symptoms and 20 million are severely ill. During the past decade, targeted interventions combining snail control, improved water quality, and the treatment of infected persons have contributed to diminishing the burden of disease.

  3. Trematodeschapter 55 • General characteristics • Trematodes are commonly called flukes • Are leaf shape worms which are generally flat and fleshy • Are hemophrodite except for schistosoma, which have separate male and female • Have complicated life cycle occuring in two or more host • have operculated eggs( except for schistosoma) which contaminated water, perpetuating the life cylce and which are also used to diagnose infections. • The first intermediate hosts are snails.

  4. Trematodes The most important trematodes are: • Schistosomaspecies (bloodflukes) • Clonorchis(liverfluke) • Paragonimus(lungfluke). Schistosomes have by far the greatest impact in terms of the number of people infected, morbidity, and mortality.

  5. SCHISTOSOMA Disease:Schistosomiasis. • Schistosoma mansoni, Schistosoma japonicum affect thegastrointestinal tract. • Schistosoma haematobium affects theurinary tract.

  6. Epidemiology: Approximately 250 million people are infected with schistosomes and 600 million are at risk

  7. SCHISTOSOMA Characteristics: • Trematode (blood fluke).Adults exist as two sexes but are attached to each other. Eggs are distinguished by spines: - Schistosoma mansonihas large lateral spine. - Schistosoma japonicumhassmall lateral spine - Schistosoma haematobiumhasterminal spine

  8. Male and female schistosomes

  9. Schistosomamansonihas large lateral spine

  10. Egg of Schistosomajaponicum with small lateral spine

  11. Schistosomahaematobiumhas terminal spine.

  12. Eggs of Schistosomahaematobiumwith terminal spine

  13. Free-swimming forked tail cercariae

  14. Life cycle of SCHISTOSOMA • In the venous site, the female lays fertilizingeggs which penetrate the gut or bladder wall. • The eggs are excreted in the stool or urine and must enter fresh water to hatch. • Once hatched, the ciliated larvae (miracidia) penetratesnailsand undergo further development into sporocysts and multiplication occurs to produce many free-swimmingcercariae • Humans are infected by free-swimming forked tailcercariae that penetrate the skin. • Cercariae form larvae ‘schistosomula’ that penetrate blood vessels and are carried to the lung and the liver, where they become adults flukes.

  15. Schistosoma Pathogenesis: Eggs in tissue induce inflammation, granulomas, fibrosis, and obstruction, especially in liver and spleenhepatosplenomegaly. • S. mansonidamages the colon(inferior mesenteric venules) • S. japonicumdamages the small intestine(superior mesenteric venules) • S. haematobium damages the bladder venules which can lead tocarcinoma of the bladder

  16. Schistosoma Transmission: • Transmitted by penetration of skin bycercariae. • Humans are definitive hosts; snails are intermediate hosts. • Endemic in tropical areas: S mansoniinAfrica and Latin America, S haematobiuminAfrica and Middle East, S japonicuminAsia

  17. Schistosoma haematobium eggs in section of bladder

  18. Portal obstruction, in liver and spleen (hepatosplenomegaly)

  19. Schistosoma Laboratory Diagnosis:Eggsvisible in feces or urine. Treatment:Praziquantel. Prevention:Proper disposal of human waste. Swimming in endemic areas should be avoided.

  20. Immunity: • IL-4 and IL-5 induces B cells to class-switch to produces IgE. • IL-5, which induces bone marrow precursors to differentiate intoeosinophils • IL-3 (along with IL-4), which stimulates mast-cell growth. • Ag / Ab activate complement.

  21. Clonorchis sinensis Disease:Clonorchiasis (chinese liver fluke) Characteristics:Trematode (liver fluke). Life cycle: • Humans ingestundercooked fishcontaining encysted larvae(metacercariae) • In duodenum, immature flukes enterbiliary duct, become adults, and release eggs that are passed in feces. • Eggs are eaten bysnails; the eggs hatch and formlarvae. • These multiply through generations and then produce manyfree-swimming cercariae, which encyst under scales of fish and are eaten by humans

  22. Clonorchis sinensis adult

  23. Clonorchis sinensis Transmission: • eatingraw or undercooked freshwater fish. • Humans are definitive hosts;snails and fishare first and second intermediate hosts, respectively. Endemic in Asia. Pathogenesis:Inflammation ofbiliary tract. Laboratory Diagnosis:Brownish, small,operculated eggsvisible in feces. Treatment:Praziquantel.  Prevention: Adequate cooking of fish. Proper disposal of human waste.

  24. Symptoms: • irritation of thebile ductswhich become dilated and deviated. • The liver may enlarge, become necrotic and tenderand its function may be impaired. • Modest infections results in indigestion, weakness and loss of weight. • Heavier infections produce anemia, liver enlargement, slightjaundice, edema, anddiarrhea.

  25. Clonorchissinensisoperculated, brownish,Small egg

  26. Paragonimus Westermani Disease:Paragonimiasis. Characteristics:Trematode (lung fluke).

  27. LIFE CYCLE • Humans ingest undercooked freshwater crab meat containing encysted larvae(metacercariae). • In gut, immature flukes enter peritoneal cavity, burrow through diaphragm into lung parenchyma, and become adults and produce eggs that enter bronchioles and arecoughed up or swallowed. • Eggs in eithersputum or fecesthat reach fresh water hatch into miracidia that entersnails, multiply through generations into larvae, and then form many free-swimmingcercariaethat infect and encyst incrabs.

  28. Paragonimus Westermani Transmission: • Transmitted by eating raw or undercookedcrab meat. • Humans are definitive hosts;snails and crabsare first and second intermediate hosts, respectively. • Endemic inAsia and India.

  29. Paragonimus westermani egg

  30. Paragonimus Westermani Pathogenesis:Inflammation and secondary bacterial infection oflung.  Laboratory Diagnosis:Eggs visible in sputum or feces. Treatment:Praziquantel. Prevention: Adequate cooking ofcrabs.Proper disposal of human waste.

  31. Features of medically important trematodes

  32. Serum creatinineconcentration is used clinically as a convenient index of kidney function, but it is important to remember that even a minimal elevation in creatinine can reflect significantly decreased rate of glomerular filtration. Hematocrit (varies with altitude): Male: 40.7-50.3% Female: 36.1-44.3%

  33. Increased eosinophils (eosinophilia) is most often associated with allergic diseases and parasites (such as worms). Possible disorders include: • eczema • leukemia • autoimmune diseases • asthma • hay fever • Medications that may cause an increase in eosinophils include: • amphetamines (appetite suppressants) • tranquilizers • bulk-type laxatives containing psyllium • certain antibiotics

  34. Other minor parasite • Fasciola Hepatica( sheep liver fluke) • Acquisition • Ingestion of aquatic plants, water cress • Reserviour: sheep, cattle, humans • Dz: subclical- fever, nightsweats, malaise • Rx: praziquantel

  35. Fasciolopsis buski (giant intestinal fluke) • Acquisition • Ingestion of acquatic plants, water chestnuts. • Reserviour Host: pigs, dogs, rabbits and humans • Progression in humans • Asymptomatic- abd pain and diarrhea • Dx: eggs in feces • Rx: Praziquantel

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