Parasitology-lec 6 Liver Flukes (kat)

LIVER FLUKES Family Fasciolidae • Relatively large distomes with the ventral sucker (acertabulum) close to the oral sucker • Terument often spinose • Testes usually branched • Vitellaria filling much of the lateral fields and confluent posterior to the testes • Uterus short • Eggs large and undeveloped when laid • Species that are parasites of man a. Fasciola hepatica – liver fluke b. Fasciola gigantica – liver fluke c. Fasciolopsis buski – intestinal fluke Fasciola hepatica Scientific name: Fasciola hepatica Common name: sheep liver fluke Disease produced: Fascioliasis hepatica Sheep liver rot pharyngeal fascioliasis or halzoun Geographic distribution: Has a cosmopolitan distribution and prevalent sheep raising countries Morphology • Large size, 20-30 mm by 8-13 mm • Flat, leaf shaped with characteristic shouldered appearance from its cephalic cone • Oral and ventral suckers of equal size on the cephalic cone • Intestine with numerous diverticula • Highly dendritic testes in tandem formation • Diffusely branched vitellatia in lateral and posterior portions of the boidy • Short convolutes uterus

Life Cycle of Fasciola hepatica. (a) adult worm in bile duct of sheep and other mammal. (b) egg (c) miracidium (d) mother sporocyst (e) mother sporocyst with developing rediae (f) redia with developing cercariae (g) free-swimming cercaria (h) mecercaria, encysted on aquatic vegetation (i) host animals eating vegetation (j) flukes released from cyst Pathology 1. acute or invasive phase – period during which the fluke migrates from the intestine to the liver and its burrowing through the liver parenchyma a. no significant change from the intestine to the liver 1. parasite may wander or be carried by blood after penetrating a blood vessel to ectopic sites such as lungs, subcutaneous tissues, brain and the orbit  abcesses or fibrotic lesions b.

migration to the liver parenchyma- traumatic and necrotic lesions

2. chronic or latent phase - period when the parasite already reached the bile ducts a. obstruction in the vessel b. inflammation and adenomatous changes of the biliary epithelium c. fibrosis of the ducts d. pressure atrophy of the liver parenchyma e. intensive periductal fibrosis f. heavy infections 1.erosion of the epithelium 2.young worms wander back into the liver a. to produce abscess pockets b. to send the vital liver tissues with their eggs

has

Symptomatology • colic and obstruction jaundice • coughing and vomiting • general abdominal rigidity • acute epigastric pain and tenderness • urticaria • early leukocytosis and eosinophilia • irregular fever • more or less persistent diarrhea • marked anemia • hemoglobinuria • cholethiasis – common complication Life cycle 1. adult flukes in bile ducts of host animals 2. egg in feces 3. eggs develop in water; hatched releasing miracidium (miracidium penetrates snail) 4. mother sporocyst 5. mother sporocyst with developing rediae 6. rediae with developing cercariae 7. cercariae released in water 8. metacercariae encysted on vegetation 9. vegetation eaten by host animals (young flukes released from cyst)

Pharyngeal fascioliasis or halzoun • due to ingestion of infected raw sheep and goat livers • adult worm lodges temporarily in the pharyngeal mucosa causing:

a. b. c. d.

edematous congestion of the soft palate, pharynx, larynx, nasal fossae, Eustachian tube  suffocation dyspnea deafness asphyxiation

Diagnosis Clinical – based on

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• biliary symptoms • moderate to high eosinophilia • eating watercress as a green salad Laboratory • recovery of the eggs in the patient’s stool or form duodenal or biliary tract drainage • serodiagnosis – helpful but not adapted for routine diagnosis

• boiling of water in areas where the infection is endemic Control measures • elimination of the snail intermediate hosts • killing the parasites in the reservoir hosts by chemotherapy

Fasciola hepatica ova

Fasciola gigantica Fasciola hepatica ova

Scientific name: Fasciola gigantica Common name: giant liver fluke

• • •

large, oval, yellowish brown operculated egg measures 130 – 150 u b y 63 – 90 u unsegmented at oviposition

Differential diagnosis • acute hepatitis of other etiology • cholecystitis • cholelithiasis • cirrhosis resulting from other causes

Disease produced: Fascioliasis gigantica Geographic distribution: parasite of herbivorous mammals particularly camels, wild hogs, cattle, and water buffalo in Africa, Asia and Hawaii

Differs from Fasciola hepatica • • • • • •

False fascioliasis –due to ingestion of infected livers Passage of eggs in the feces *Keep the patient on a liver free diet for 3 days or more

more elongated or lanceolate cephalic cone is shorter and les prominent ventral sucker is larger testes are more anterior in position shoulders are practically lacking eggs are larger

false fascioliasis – eggs no longer seen true fascioliasis – eggs can still be seen Epidemiology • definitive hosts are herbivorous animals like sheep • man is an accidental final host

• • • •

1st intermediate host – Lymneid snail a. Lymnaea philippinensis b. Lymnea swinhoe 2nd intermediate host – aquatic vegetation – watercress humans contract the disease by ingesting plants sush as watercress or possibly water containing the encysted metacercaria herbivorous or omnivorous animals acquire the infection in low, damp pastures, where the vegetation is infested with metacercaria

*Lymnea swinhoei – 1st intermediate host of Fasciola hepatic in Taiwan

Family Opistorchiidae • parasites of the bile ducts and gall bladder • small to medium-sized, usually elongate and relatively delicate with weakly developed suckers • testes located posteriorly may be branched or lobed • ovary is near midbody • coiled uterus fills the area between the ovary and ventral sucker • eggs are small and are fully embryonated Clonorchis sinensis Scientific name: Clonorchis sinensis Common name: Chinese liver fluke

Treatment • bithionol (dichlorophenol) – 30-50 mg/kg per body weight on alternate days to complete 10-15 doses • dehydroemetine hydrochloride – 1 mg per kg daily intramuscularly for 10 days • emetine hydrochloride – 30 mg daily for 17-18 days intramuscularly or 40 mg daily to a total of 5 mg/ kg body weight • hexachloroparaxylene – favorable results as reported from Russia • praziquantel – probably effective as in other liver fluke infections Prevention and Control Preventive measures • thorough washing or cooking of vegetables

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Disease produced: Clonorchiasis Geographic distribution: • an important parasite of Humans in the Far East • a parasite of fish eating mammals and humans in Japan, China, South Korea, Formosa and Vietnam Morphology • flat, spatulate,aspinous, flabby, transparent gray worm tapering anteriorly and somewhat rounded psoteriorly • measures 12-20 mm (10-25 mm) by 3-5 mm • ventral sucker smaller that oral sucker • long intestinal ceca extending to the posterior end • large deeply lobulated or branched testes in tandem formation in the posterior third of the body

• • •

small, slightly lobate ovary anterior to the testes in the midline loosely coiled uterus arising from the ootype ending in the common genital pore minutely follicular vitellaria in the lateral midportion of the body

Pathology • distal bile ducts are irritated mechanically and by toxic secretions • slight leukocytosis and eosinophilia in early infection • enlarged tender liver • bile ducts thicken and become dilated and tortuous • adenomatous proliferation of the biliary epithelium • fibrosis and destruction of hepatic parenchyma • liver function is impaired although SGPT and SGOT are normal

Life cycle 1. 2. 3. 4. 5. 6. 7.

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egg containing miracidium miracidium hatches after being eaten by snail sporocyst redia cercaria cercaria leaves snail and penetrates fish metacercarial cysts in fish muscle human (adult in bile duct liver)

*Cholangiocarcinoma of the liver. Severe chronic infection may lead to marked pericholangitic fibrosis and finally mulitfocal cholangiocellular carcinoma of the liver

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Symptomatology • light infection – produce only mild symptoms or go unnoticed • moderate infections: indigestion, epigastric discomfort unrelated to meals, weakness, loss of weight • heavy infections – complicated by cholekethiasis and bouts of pyogenic cholangitis Epidemiology • man is the definitive host

• • •

1st intermediate host – operculate snails of several genera, including Alocinma and Parafossarulus, Bithynia (Bulimus), Semisulcospira, Melanoides, tuberculatus 2nd intermediate host – fresh water fish of the family Cyprinidae, Ctenopharyngodon idellus humans are usually infected by: eating uncooked fish containing the infective metacercaria, ingestion of the cysts in drinking water

*Ctenopharyngodon idellus, a common host for cercariae of Clonorchis sinensis Diagnosis Life cycle of Clonorchis sinensis (a) Egg containing miracidium is passed in feces. (b) Miracidium hatches after being eaten by snail. (c) Sporocyst. (d) Redia (e) Cercaria leaves snail and penetrates fish (f) Metacercarial cysts in fish muscle. (g) Human becomes infected by eating raw fish (h) adult fluke in bile duct.

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Clinical – suggestive in patients from endemic areas With • history of eating uncooked fish • symptoms of biliary tract disease 1. intermittent jaundice 2. bouts of fever 3. right upper quadrant pain Laboratory

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finding the characteristic eggs in the feces or biliary drainage or duodenal aspiration eggs to be differentiated from opistorchid and heterophyic flukes

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2 testes lobed and situated obliquely to each other in the posterior fourth of the worm ovary small, oval or slightly lobed is median in position just in front of the anterior end of the bladder vitellaria consist of numerous transversely compressed follicles disposed in the lateral fields in the middle third of the body uterus- an intricately coiled tubule form the ootype that proceeds anteriad

Clonorchis sinensis ova • • •

•

broadly ovoid, 29 X 16 u has a moderately thick, light yellowish brown shell at the smaller end is a distinct convex operculum which fits into a rimmed extension of the shell at the thicker posterior end is a small median protuberance

Life cycle 1. adult worms in biliary tract or small intestine 2. eggs excreted on moist soil or water 3. miracidia hatch from eggs of some species. Eggs of other species eaten by snails (1st intermediate host) 4. after multiplication, cercariae emerge from snail 5. some species encyst on gills, scales or muscles of fish. Other species encyst on aquatic plants (2nd intermediate host) 5. metacercariae ingested (by man/cat)

Treatment • Choloroquine diphosphate – 250 mg TID for 6 weeks (with treatment failure and side effects including optic neuropathy) • Praziquantel – 25 mg/lg TID for 2 consecutive days or 75 mg/kg in 3 doses 4 to 6 hours apart (no treatment failure and only mild side effects: h eadache and dizziness) • Heavy infections complicated by obstructive jaundice: 1. cholecystectomy with choledocholithotomy 2. exploration of the common duct 3. drainage procedure such as sphincteroplasty or choledochoduodenostomy Preventive measures • Thorough cooking of all freshwater fish Control measures • Education of the public to break the habit of eating raw fish after seasoning with condiments • Stopping the seeding of fish culture ponds • Sterilization of human feces by storage or by the addition of ammonium sulfate • Human and animal feces should not be disposed in bodies of water Opistorchis felineus Scientific name: Opistorchis felineus Common name: cat liver flukes Disease produced: Opistorchiasis felineus Geographic distribution: • Prevalent in eastern and southeastern Europe and Asiatic areas of the former USSR • Found in humans in the highly endemic areas of Poland and the Dnieper, Donetz and Desna basins

Morphology • • • • •

Lancet in shape 7-12 mm X 2-3 mm Rounded posteriorly and attenuated anteriorly Thin and transparent, reddish bile colored Has a smooth integument Two suckers equal in diameter; oral sucker subterminal

Pathology • inflammatory and proliferative changes of the biliary epithelium • fibrosis of the distal biliary vessels

•

pathologic changes may extend to the proximal bile ducts and gallbladder  periportal fibrosis

Symptomatology • light infections – asymptomatic • moderate infections 1. moderate, painful enlargement of the liver 2. passive congestion of the spleen 3. icterus 4. local eosinophilia in the wall of the bile ducts • heavy infections 1. invade the pancreas with digestive disturbances 2. bile stones mau form around eggs as nuclei and cause cholecystitis with colic 3. loss of appetite as patient becomes toxic 4. scar tissue around the bile ducts encroaches on liver cells and portal vessels  collateral venous circulation, edema of the face and limbs and at times ascitis Epidemiology • definitive hosts – cats, dogs, fox, wolves, seals

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accidental final host – man 1st intermediate host –amnicolid snail Bithynia (Bulimus) leachi 2nd intermeciate host – fresh water fish (cyprinoid fish) Tinca tinca, Idus melanotus, Barbus barbus, Cyprinus carpio, Abramis brama, A. sapa, ALburnus Iucidus, Aspius aspius, Blicca bjorkna, Leuciscus rutilis and Scardiinius erythopthalamus the infection is acquired by eating raw or insufficiently cooked fish harboring the metacercaria intermediate snail hosts are infected by feces deposited on sandy shores and washed into streams

It can be distinguished form Opistorhis felineus • Greater proximity of its ovary and testes both of which are deeply lobulated • Aggregation of its vitellaria into a few clusters of glandular material • Esophagus is elongated

Life Cycle

* Bithynia funiculate – 1st intermediate host of Opistorchis felineus

* Cyprinus carpio, 2nd intermediate host of Opistorchis felineus in Taiwan Laboratory diagnosis • recovery of the typical eggs in the stool or by duodenal intubation 1. elongate, ovoid in shape with an operculum that fits into a thickened rim of the shell proper 2. light yellowish brown and are about three times as long as broad 3. a minute tubercular thickening at the posterior end 4. has a miracidium when laid 5. resembles Clonorchis sinensis but: a. are narrower and have more tapering ends b. a pointed terminal knob c. a less conspicuous opercular Treatment • Praziquantel – 40 mg/kg body weight in a single dose after meal Side effects – abdominal pain, vomiting, diarrhea, lassitude, myalgia, headache and rashes Prevention • Cooking of fish or abstain form eating raw or inadequately cooked fish • Sanitary excreta disposal not effective – reservoir hosts and man pollute the waters containing the intermediate hosts

Pathologic changes • Dilatation and thickening of bile duct walls • Presence of stones and sludge in the gallbladder • Hyperplastic biliary epithelium form presence of worms • Further stimulated by nitrosamines in local fermented foods or by nitrosocompounds produced by activated macrophages in chronically affected tissues • Striking association with cholangiocarcinoma Symptomatology • Mild to moderate infections – few symptoms • Heavy infections 1. abdominal distress 2. epigastric pain 3. generalized malaise Epidemiology •

Opistorchis viverrini

• • Scientific name: Opistorhis viverrini Common name: Disease produced: Opistorchiasis viverrini Geographic distribution: an important human parasite in northeastern Thailand and in the northernmost province of Udorn

• •

Definitive hosts – civet cat, cat, dog and other fish eating mammals Accidental final host – man 1st intermediate host – snails 1. Bithynia goniomphalus 2. Bithynia funiculate 3. Bithynia laevis 2nd intermediate host – fresh water fish 1. Punteus orphoides 2. Hampala dispar 3. Cyclocheilichthys siaja infection is acquired by eating uncooked fish containing the infective metacercaria

Laboratory diagnosis • finding eggs in feces or in duodenal aspirates (eggs are relatively short and broad with a length of 36.7 um and breadth of 15 um)

Morphology

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9. ant accidentally eaten by sheep

•

ultrasonography – to screen fot he presence of cholangiocarcinoma

Treatment • Praziquantel -25 mg/kg body weight TID for 2 days Prevention and Control • Same as Opistochis felineus and Clonorchis sinensis Family Dicrocoellidae • • • •

Small to medium-sized flukes that live in the bile or pancreatic ducts of birds and mammals Elongate with well developed suckers Notable feature – position of the testes anterior to the ovary Eggs are small with a thick brown shell and embryonated when laid

Dicrocoelium dendrticulum Scientific name: Dicrocoelium dendriticum Common name: lancet fluke Disease produced: Dicrocoeliasis Geographic distribution: has a cosmopolitan distribution in sheep and other herbivore in Asia, Africa, Europe and North and South America Morphology • Slender, lancet shaped, flat transparent, aspinous body 5-15 mm by 1.5-2.5 mm • Acetabulum lies at the beginning of the second fifth of the body • 2 large, slightly lobed testes situated obliquely to each other anterior to the small subglobose ovary just behind the ventral sucker • voluminous uterine coils in the posterior thirds of the worm • subglobose ovary lies to the right of themidline and somewhat anterior to the equator of the worm • discrete vitelline follicles occupy lateral fields in the midline of the body

Life cycle of Dicrocoelium dendriticum. (a) Adult, in bile duct of sheep or other plant-eating mammal. (b) Egg released in feces. (c) Miracidium hatching from egg after being eaten by snail (d) Mother sporocyst (e) Daughter sporocyts (f) Cercariae escaping from snail in slimeball (g) Slimeballs containing cercariae by ant (h) Metacercaria encysting in ant. (i) Ant accidentally eaten by sheep Pathology –same as Fasciola hepatica In animals • enlargement of the bile ducts • hyperplasia of the biliary epithelium • formation of the periductal fibrous connective tissue • arophy of the liver cells • portal cirrhosis in heavy infections In humans • hepatic changes are less pronounced Symptomatology In humans • digestive disturbances • flatulence • vomiting • biliary colic • chronic constipation or diarrhea • enlarged liver • systemic toxemia less pronounced than in fascioliasis Epidemiology • principal definitive host – sheep and other herbivorous mammals • accidental final host – man

Life cycle 1. adult worm develops in bile duct of sheep or other plant-eating mammal 2. eggs released in feces (miracidium in egg) 3. miracidium hatches from egg after being eaten by snail 4. mother sporocyst 5. daughter sporocyst 6. cercariae escaping from snail in slimeball 7. slimeball containing cercariae eaten by ant 8. metacercaria encysts in ant

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• • •

1st intermediate hosts – land snails of the genera Abida, Cochlicopa, Helicella and Zebrina 2nd intermediate hsots – ants, (Formica fusca) infection of the mammalian definitive host and man is by the ingestion of ants harboring the metacercaria

Laboratory diagnosis • finding the eggs consistently in the feces and duodenal drainage

•

*eggs are deep golden-brown thick shelled, distinctly operculated, measuring 38-45 u by 22-30 u containing a fully developed miracidium

eliminate spurious infections form eating livers containing the eggs

Treatment – same as Clonorchis sinensis • praziquantel – 25 mg/kg TID for 2 consecutive days Prevention and Control • no effective measures of control • fresh herbs collected from grazing areas for use as food for humans should be washed to remove ants

Scientific name

Common name

Infective Diagnostic stage stage ___________________________________________________________________________ Fasciola hepatica sheep liver fluke metacercaria unembryonated ova ___________________________________________________________________________ Fasciola gigantica giant liver fluke metacercaria unembryonated ova ___________________________________________________________________________ Clonorchis sinensis Chinese liver fluke metacercaria embryonated ova ___________________________________________________________________________ Opistorchis felineus cat liver fluke metacercaria embryonated ova ___________________________________________________________________________ Opistorchis metacercaria embryonated ova viverrini ___________________________________________________________________________ Dicrocoelium lancet fluke metacercaria embryonated ova dendriticum ____________________________________________________________________________

Scientific name 1ST IH 2ND IH FH AFH ___________________________________________________________________________ Fasciola hepatica snail aquatic vegetation herbivorous animals man like sheep ___________________________________________________________________________ Fasciola gigantica snail aquatic vegetation camels, wild hogs, man cattle and water buffalo ___________________________________________________________________________ Clonorchis sinensis snail fresh water fish man ___________________________________________________________________________ Opistorchis felineus snail fresh water fish cats, dogs,fox,wolves seals man ___________________________________________________________________________ Opistorchis snail fresh water fish civet cat, cat,dog man viverrini and other fish eating mammals ___________________________________________________________________________ Dicrocoelium snail ants sheep man dendriticum ___________________________________________________________________________ [email protected]

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