1. 1 Trematodes Faculty: Samuel Aguazim, M.D. Lange Chapter 55Lange Chapter 55

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3. Schistosomiasis It is believed that Napoleon's army in North Africa was not defeated by the enemy but by infestation of his soldiers with Schostosomal infections. 3

4. 4 Trematodes The most important trematodes are: Schistosoma species (blood flukes) Clonorchis (liver fluke) Paragonimus (lung fluke). Schistosomes have by far the greatest impact in terms of the number of people infected, morbidity, and mortality.

5. Trematodes 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 cycle and which are also used to diagnose infections. The first intermediate hosts are snails. 5

6. TrematodeMode of Transmiss ion Main site affected Intermedi ate Host(s) Diagnostic Features of Eggs Endemic areatreatment s. mansoniPenetrate skin Veins of colon SnailLarge lateral spine Africa, latin american, carribean praziquantel s.JaponicumSameVeins of small intestine and liver SameSmall lat spine AsiaSame s.Haematobiu m SameVeins of urinary bladder SameLarge terminal spine Africa, middle east Same C.SinensisIngested with raw fish LiverSnail and fish OperculatedAsiaSame p.WestermaniIngested with raw crab LungSnail and crab OperculatedAsia, indiasame 6

7. 7 SCHISTOSOMA Disease: Schistosomiasis. Schistosoma mansoni, Schistosoma japonicum affect the gastrointestinal tract. Schistosoma haematobium affects the urinary tract.

8. 8 Epidemiology: Approximately 250 million people are infected with schistosomes and 600 million are at risk

9. 9 SCHISTOSOMA Characteristics: Trematode (blood fluke). Adults exist as two sexes but are attached to each other. Eggs are distinguished by spines: - Schistosoma mansoni has large lateral spine. - Schistosoma japonicum has small lateral spine - Schistosoma haematobium has terminal spine.

10. 10 Male and female schistosomes.

11. 11 Schistosoma mansoni has large lateral spine

12. 12 with small lateral spine Egg of Schistosoma japonicum with small lateral spine

13. 13 Schistosoma haematobium has terminal spine.

14. 14 with terminal spine Eggs of Schistosoma haematobium with terminal spine

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16. 16 Free-swimming forked tail cercariae

17. 17 Life cycle of SCHISTOSOMA see slide 11 In the venous site, the female lays fertilizing eggs 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) penetrate snails and undergo further development into sporocysts and multiplication occurs to produce many free-swimming cercariae Humans are infected by free-swimming forked tail cercariae 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.

18. 18 Schistosoma Pathogenesis: Eggs in tissue induce inflammation, granulomas, fibrosis, and obstruction, especially in liver and spleen hepatosplenomegaly. S. mansoni damages the colon (inferior mesenteric venules) S. japonicum damages the small intestine (superior mesenteric venules) S. haematobium damages the bladder venules which can lead to carcinoma of the bladder.

19. Clinical findings T he acute stage, which begins shortly after cercarial penetration, consists of itching and dermatitis followed 2-3 weeks later by fever, chills, diarrhea, lymphadenopathy, and hepatosplenomegaly. Eosinophilia is seen in response to the migrating larvae. This stage usually resolves spontaneously. 19

20. Clinical findings The chronic stage can cause significant morbidity and mortality. In patients with S. mansoni or S. japonicum infection, gastrointestinal hemorrhage, hepatomegaly, and massive splenomegaly can develop. The most common cause of death is exsanguination from ruptured esophageal varices. Patients infected with S. haematobium have hematuria as their chief early complaint. Superimposed bacterial urinary tract infections occur frequently. 20

21. 21 Schistosoma Transmission: Transmitted by penetration of skin by cercariae. Humans are definitive hosts; snails are intermediate hosts. Endemic in tropical areas: S mansoni in Africa and Latin America, S haematobium in Africa and Middle East, S japonicum in Asia.

22. 22 Schistosoma haematobium eggs in section of bladder

23. 23 Portal obstruction, in liver and spleen (hepatosplenomegaly)

24. Blood Flukes: Schistosomiasis 24

25. 25 Schistosoma Laboratory Diagnosis: Eggs visible in feces or urine. Treatment:Praziquantel. Prevention: Proper disposal of human waste. Swimming in endemic areas should be avoided.

26. nonhuman schistosomes. "Swimmer's itch," which consists of pruritic papules, is a frequent problem in many lakes in the United States. The papules are an immunologic reaction to the presence in the skin of the cercariae of nonhuman schistosomes. These nonhuman schistosomes are incapable of replicating in humans and do not cause disseminated disease. 26

27. 27 Immunity: IL-4 and IL-5 induces B cells to class-switch to produces IgE. IL-5, which induces bone marrow precursors to differentiate into eosinophils IL-3 (along with IL-4), which stimulates mast- cell growth. Ag / Ab activate complement.

28. 28 Clonorchis sinensis Disease: Clonorchiasis Characteristics: Trematode (liver fluke). Life cycle: Humans ingest undercooked fish containing encysted larvae (metacercariae) In duodenum, immature flukes enter biliary duct, become adults, and release eggs that are passed in feces. Eggs are eaten by snails; the eggs hatch and form larvae. These multiply through generations and then produce many free-swimming cercariae, which encyst under scales of fish and are eaten by humans

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30. 30 Clonorchis sinensis adult

31. 31 Clonorchis sinensis Transmission: eating raw or undercooked freshwater fish. Humans are definitive hosts; snails and fish are first and second intermediate hosts, respectively. Endemic in Asia. Pathogenesis: Inflammation of biliary tract. Laboratory Diagnosis: Brownish, small, operculated eggs visible in feces. Treatment:Praziquantel. Prevention:Adequate cooking of fish. Proper disposal of human waste.

32. 32 Symptoms: irritation of the bile ducts which become dilated and deviated. The liver may enlarge, become necrotic and tender and its function may be impaired. Modest infections results in indigestion, weakness and loss of weight. Heavier infections produce anemia, liver enlargement, slight jaundice, edema, and diarrhea. Clonorchis sinensis

33. 33 Clonorchis sinensis operculated, brownish, Small egg

34. 34 Paragonimus Westermani Disease: Paragonimiasis. Characteristics: Trematode (lung fluke).

35. 35 Life cycle:Paragonimus Westermani 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 are coughed up or swallowed. Eggs in either sputum or feces that reach fresh water hatch into miracidia that enter snails, multiply through generations into larvae, and then form many free-swimming cercariae that infect and encyst in crabs.

36. Lung Flukes: Paragonimus westermani Life Cycle 36

37. 37 Paragonimus Westermani Transmission: Transmitted by eating raw or undercooked crab meat. Humans are definitive hosts; snails and crabs are first and second intermediate hosts, respectively. Endemic in Asia and India.

38. 38 Paragonimus westermani egg

39. Lung Flukes: Pathogenesis and Clinical Manifestations Paragonimiasis –Cough –Hemoptysis –Symptoms consistent with pulmonary tuberculosis –Misdiagnosed as PTB  fluke may migrate to brain, produce eggs and cause epilepsy-like symptoms 39

40. 40 Paragonimus Westermani Pathogenesis: Inflammation and secondary bacterial infection of lung. Laboratory Diagnosis: Eggs visible in sputum or feces. Treatment:Praziquantel. Prevention:Adequate cooking of crabs. Proper disposal of human waste.

41. 41 Features of medically important trematodes

42. 42 Serum creatinine concentration 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%

43. 43 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

44. TREMATODES OF MINOR IMPORTANCE Fasciola Hepatica ( sheep liver fluke) Acquisition Ingestion of aquatic plants, water cress Reserviour: sheep, cattle, humans Dz: subclical- fever, nightsweats, malaise Rx: praziquantel 44

45. Liver Flukes Fasciola species 45

46. 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 46

47. Intestinal Flukes: Life cycle of Fasciolopsis buski 47

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49. MINOR PARASITE 49

50. Anisakis simplex The larvae of A. simplex cause anisakiasis. They are ingested in raw seafood, such as sashimi and sushi, and migrate into the submucosa of the intestinal tract. Acute infection resembles appendicitis. Diagnosis is not dependent on the clinical laboratory. There is no effective drug therapy. Prevention consists of not eating raw fish 50

51. ECTOPARASITE 51

52. Pediculus humanus & Phthirus pubis Disease Pediculosis. Characteristics Lice are easily visible. P. humanus has an elongated body, whereas P. pubis has a short body resembling a crab. Nits are the eggs of the louse, often attached to the hair shaft or clothing. 52

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54. Transmission :Hair and body lice are transmitted from human to human by contact, especially fomites such as hats and combs. Pubic lice are transmitted by sexual contact. Pathogenesis: Itching is caused by a hypersensitivity response to saliva of the louse. Excoriations may result from scratching and secondary bacterial infections may occur Laboratory Diagnosis :Not involved. Treatment : Permethrin. Prevention : Personal items should be treated or discarded. 54

55. Dermatobia hominis Disease: Myiasis. Characteristics: Fly larvae (maggots) cause the disease not the adult flies. Transmission :Adult fly deposits egg in lesion. Egg hatches to form larva. Dermatobia deposits its egg on mosquito, and when the mosquito bites the eggs are then deposited on the skin. Pathogenesis: Larva induces an inflammatory response. Laboratory Diagnosis :Not involved. Treatment :Surgical removal of larva. Prevention :Limit exposure to flies and mosquitoes. 55

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58. Bedbugs: Cimex lectularius is the most common bedbug found in the United States. It has an oval, brownish body and is about 5 mm long. Bedbugs reside in mattresses and in the crevices of wooden beds. At night, they emerge to take a blood meal from sleeping humans. The main symptom is a pruritic wheal caused by a hypersensitivity reaction to proteins in the bug saliva. Some individuals show little reaction. The bite of a bedbug is not known to transmit any human disease. Calomine lotion can be used to relieve the itching. Malathion or lindane can be used to treat mattresses and beds. 58

59. Sarcoptes scabiei Disease: Scabies. Characteristics Round body with eight short legs. Too small to be seen with naked eye. Transmission Person-to-person contact or fomites such as clothing. Pathogenesis: Itching is caused by a hypersensitivity response to feces of the mite. Laboratory Diagnosis: Microscopic examination reveals mites and their feces. Treatment: Permethrin. Prevention: Treat contacts and discard fomites. 59

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61. Dermacentor Species Disease: Tick paralysis. Characteristics: Certain species of ticks produce a neurotoxin. Transmission: Ticks reside in grassy areas and attach to human skin. Pathogenesis: Female tick requires a blood meal and toxin enters in tick saliva at bite site. Neurotoxin blocks release of acetyl choline at neuromuscular junction. Similar action as botulinum toxin. Laboratory Diagnosis: Not involved. Treatment: Removal of tick results in prompt reversal of paralysis. Prevention: Remove ticks; wear protective clothing. 61

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63. Latrodectus mactans (Black Widow Spider) Disease: Spider bite. Characteristics Black widow spiders have an orange-red hourglass on their ventral surface. Pathogenesis: Neurotoxin causes pain in extremities and abdomen. Numbness, fever, and vomiting also occur. Laboratory Diagnosis: Not involved. Treatment: Antivenom should be given in severe cases. 63

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65. Loxosceles reclusa (Brown Recluse Spider) Disease: Spider bite. Characteristics Brown recluse spiders have a violin-shaped pattern on their dorsal surface. Pathogenesis Dermotoxin is a protease that causes painful necrotic lesions Laboratory Diagnosis Not involved. Treatment Antivenom is not available in the United States. 65

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71. THE BEAUTY IN EVERY BEAST IS FOR HIM/HER TO REMEMBER… I AM CREATED FOR IMPACT NOT FOR SURVIVAL!!!!!!!!!!! DRS 71