Liver Flukes

Family Fasciolae

-relatively large distomes with he ventral sucker (acetabulum) close to the oral sucker-tegument 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 ha are parasites of man

-fasciola hepatica (liver)-f. gigantica (liver)-f. buski (intestinal)

Fasciola Hepatica

-common name: sheep liver fluke-dse produced: fasciolasis hepatica, sheep liver rot, pharyngeal fasciolasis or halzoun-geographic distribution: has a cosmopolitan distribution and prevalent in sheep raising countries

Morphology-large size: 20 to 30 m by 8 to 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 vitellaria in lateral and posterior portions of the body-short convoluted uterus

Pathology1. 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 liveri. 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 abscesses or fibrotic lesions

b. Migration to the liver parenchyma- traumatic and necrotic lesions

2. Chronic or latent phase- period when the parasite has already reached the bile ducts

a. Obstruction in the vesselb. Inflammatory and adenomatous changes of the

biliary epithelium c. Fibrosis of the ductsd. Pressure atrophy of the liver parenchymae. Intensive periductal fibrosisf. Heavy infections

i. Erosion of the epitheliumii. Young worms wander back into the liver

1. to produce abscess pockets2. to seed the vital liver tissue

with their eggs

Symptomatology-colic and obstructive jaundice-coughing and vomiting-generalized abdominal rigidity-acute epigastric pain and tenderness-urticaria

-early leukocytosis and eosinophilia-irregular fever-more or less persistent diarrhea-marked anemia-hemoglobinuria-cholelithiasis: common complication

Pharyngeal fasciolasis or halzoun1. due to ingestion of infected raw sheep and goat livers2. adult worm lodges temporarily in the pharyngeal mucosa

causing:a. edematous congestion of the soft palate, pharynx,

larynx, nasal fossae, eusachian tube suffocation

b. dyspneac. deafnessd. asphyxiation

DiagnosisClinical- based on:-biliary symptoms-moderate to high eosinophilia-eating watercress as a green salad

Laboratory-recovery of the eggs in the patient’s stool or from duodenal or biliary tract drainage-serodiagnosis: helpful but not adapted for routine diagnosis

Ova-large, oval, yellowish brown operculated egg-measures 130 to 150 u by 63 to 90 u-unsegmented at oviposition

Differential Diagnosis-acute hepatitis of other etiology-cholecystitis-cholelithiasis-cirrhosis resulting from other causes

False fasciolasis- due to ingestion of infected livers with passage of eggs in the feces

Keep the patient on a liver free diet for 3 days or moreFalse fasciolasis- eggs no longer seenTrue fasciolasis- eggs can still be seen

Epidemiology-definitive hosts are herbivores like sheep-man is an accidental final host-1st intermediate host- lymneid snail

a. lymnaea philippinensisb. lymnea swinhoe- 1st IH in Taiwan

-2nd intermediate host- aquatic vegetation (watercress)-humans contract the disease by ingesting plants such as watercress or possibly water containing the encysted metacercaria-herbivores or omnivores acquire the infection in low, damp pastures, where the vegetation is infested with metacercaria

Treatment-bithionol (dicholorophenol): 30 to 50 mg/kg per body weight on alternate days to complete 10 to 15 doses-dehydroemetine hydrochloride: 1 mg per kg daily intramuscularly for 10 days-emetine hydrochloride: 30 mg daily for 17 to 18 days IM 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

Preventive Measures-thorough washing or cooking of vegetables-boiling of water in areas where the infection is endemic

Control Measures-elimination of the snail IH-killing the parasites in the reservoir hosts by chemotherapy

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SUBJECT: Micro / ParaLecturer: Dra. ReyesTopic: Liver FlukesDate: Feb. 28, 2008TransGrp: 18-20, 24

Fasciola Gigantica

-common name: giant liver fluke-dse produced: fasciolasis gigantica-geographic distribution: parasite of herbivores mammals particularly camels, wild hogs, cattle and water buffalo in Africa, Asia, and Hawaii

Differs from F.hepatica-more elongated or lanceolate-cephalic cone is shorter and less prominent-ventral sucker is large-testes are more anterior in position-shoulders are particularly lacking-eggs are larger

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

-common name: Chinese liver fluke-dse produced: clonorchiasis-geographic distribution:

-an important parasite of humans in the Far East, - 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 posteriorly-measures 12 to 20 mm (10 to 25 mm) by 3 to 5 mm-ventral sucker smaller than 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 its toxic secretions-slight leukocytosis and eosinophilia in early infection-enlarged tender liver-bile ducts thicken and become dilated and tortous-adenomatous proliferation of the biliary epithelium -fibrosis and destruction of hepatic parenchyma-liver function is impaired although SGPT and SGOT are normal

Cholangiocarcinoma of the Liver- severe chronic infection may lead to marked pericholangitic fibrosis and finally multifocal cholangiocellular carcinoma of the liver

Symptomatology-light infections: produce only mild symptoms or go unnoticed-moderate infections: indigestion, epigastric discomfort unrelated meals, weakness, loss of weight-heavy infections: complicated by cholelithiasis and bouts of pyogenic cholangitis

Epidemiology-man is the definitive host-1st IH: operculate snails of several genera including Alocinma and Parafossarulus, Bithynia (Bulimus), Semisulcospira, Melanoides tuberculatus-2nd IH: fresh water fish of the family Cyprinidae, Ctenopharyngodon idellus

-humans are usually infected by:-eating uncooked fish containing the infective metacercariae-ingestion of the cysts in drinking water

DiagnosisClinical-suggestive in patients from endemic areas with:-history of eating uncooked fish-symptoms of biliary tract disease

-intermittent jaundice-bouts of fever-RUQ pain

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

Ova-broadly ovoid, 29 by 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

Treatment-chloroquine diphosphate: 250 mg TID for 6 weeks with treatment failure and side effects including optic neuropathy-praziquantel: 25 mg/kg 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 (headache and dizziness)-heavy infections complicated by obstructive jaundice:

-cholecystectomy with choledocholithotomy-exploration of the common duct-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 Sinensis

-common name: cat liver fluke-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 to 12 mm by 2 to 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-two 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 midline third of the body-uterus: an intricately coiled tubule from the ootype that proceeds anteriad

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 gall bladder periportal fibrosis

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Symptomatology-light infections: asymptomatic-moderate infections:

-moderate, painful enlargement of the liver-passive congestion of the spleen-icterus-local eosinophilia in the wall of the bile ducts

-heavy infections:-invade the pancreas with digestive disturbances-bile stones may form around eggs as nuclei and cause

cholecystitis with colic-loss of appetite as patient becomes toxic-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 ascites

Epidemiology-definitive hosts: cats, dogs, fox, wolves, seals-accidental final host: man-1st IH: amnicolid snail Bithynia (Bulimus) leachi-2nd IH: freshwater fish (cyprinoid fish), Tinca tinca, Idus melanotus, Barbus barbus, Cyprinus carpio (Taiwan), Abramis brama, A sapa, Alburnus lucidus, Aspius aspius, Blicca bjorkna, Leuciscus rutilis and Scardiinius erythopthalmus-the infection is acquired by eating raw or insufficiently cooked fish harboring the metacarcariae-intermediate snail hosts are infected by feces deposited on sandy shores and washed into streams

Laboratory Diagnosis-recovery of the ypical eggs in the stool or by duodenal intubation

-elongate, ovoid in shape with an operculum that fits into a thickened rim of the shell proper

-light yellowish brown and are about 3 times as long as broad

-a minute tubercular thickening at the posterior end-has a miracidium when laid-resembles Chlonorchis sinensis but:

-are narrower and have more tapering ends-a pointed terminal knob-a less conspicuous opercular

Treatment-praziquantel: 40 mg/kg body weight in a single dose after a meal

Side effects: abdominal pain, vomiting, diarrhea, lassitude, myalgia, headache, and rashes

Prevention-cooking of fish or abstain from eating raw or inadequately cooked fish-sanitary excreta disposal not effective: reservoir hosts and man pollute the waters containing the IH

Opistorchis Vivernini

-dse produced: Opistorchiasis vivernini-geographic distribution: an important parasite in northeastern Thailand and in the northernmost province of Udorn

Morphology-can be distinguished from O felineus:

-greater proximity of is ovary and testes, both of which are deeply lobulated

-aggregation of is vitellaria into a few clusters of glandular material

-esophagus is elongated

Pathologic Changes-dilatation and thickening of bile duct walls-presence of stones and sludge in the gall bladder-hyperplastic biliary epithelium from presence of worms-further simulated by nirosamines 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:

-abdominal distress-epigastric pain-generalized malaise

Epidemiology-definitive hosts: civet cat, cat, dog and other fish eating mammals-accidental final host: man-1st IH: snails (Bithynia goniumphalus, B funiculate, B laevis)-2nd IH: freshwater fish (Punteus orphoides, Hampala dispar, Cyclocheilichthys siaja)-infection is acquired by eating uncooked fish containing the infective metacercariae

Laboratory Diagnosis-finding eggs in feces or duodenal aspirates: eggs are relatively short and broad with a length of 26.7 um and breadth of 15 um-ultrasonography: to screen for the presence of cholangiocarcinoma

Treatment-praziquantel: 25 mg/kg body weight 3x daily for 2 days

Prevention and Control-same as O felineus and C sinensis

Family Dicrocoellidae

-small o 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 Dendriticum

-common name: lance fluke-dse 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 to 15 mm by 1.5 to 2.5 mm-acetabulum lies at the beginning of the second fifth of the body-two 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 the midline and somewhat anterior to the equator of the worm-discrete vitelline follicles occupy lateral fields in the midline of the body

Pathology-same as F hepatica-in animals

-enlargement of the bile ducts-hyperplasia of the biliary epithelium-formation of the periductal fibrous connective tissue-atrophy 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 fasciolasis

Epidemiology-principal definitive host: sheep and other herbivores

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-accidental final host: man-1st IH: land snails of the genera Abida, Cochlicopa, Helicella and Zebrina-2nd IH: ants (Formica fusca)-infection of the mammalian definitive host and man is by ingestion of ants harboring the metacercaria

Laboratory Diagnosis-finding the eggs consistently in the feces and duodenal drainage-eliminate spurious infections from eating livers containing the eggs-eggs are deep golden brown, thick shelled, distinctly operculated, measuring 38 to 45 u by 22 to 30 u containing a fully developed miracidium

Treatment-same as C 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 the ants

Scientific name

Common name

Infective stage

Diagnostic stage

F hepatica Sheep liver fluke

metacercaria Unembryonated ova

F gigantica Giant liver fluke

metacercaria Unembryonated ova

C sinensis Chinese liver fluke

metacercaria Embryonated ova

O felineus Cat liver fluke metacercaria Embryonated ova

O vivernini metacercaria Embryonated ova

D dendriticum Lancet fluke metacercaria Unembryonated ova

Scientific name

1st IH 2nd IH FH AFH

F hepatica snail Aquatic vegetation

Herbivores, sheep

man

F gigantica snail Aquatic vegetation

Camels, wild hogs, cattle, water buffalo

man

C sinensis snail Freshwater fish

man

O felineus snail Freshwater fish

Cats, dogs, fox, wolves, seals

man

O vivernini snail Freshwater fish

Civet cat, cat, dog, and other fish eating animals

man

D dendriticum snail ants sheep man

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