FASCIOLA HEPATICA - PowerPoint Presentation

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FASCIOLA HEPATICA

MUZAFFAR KHAN ALAM KHAN

Student of TSMUSlide2

A Parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism & which causes harm to the host without immediately killing it.

Every free-living species has its own unique species of parasite, so the number of parasitic species greatly exceeds the number of free living species.

ParasiteSlide3

PARASITOLOGY & MEDICAL PARASITOLOGY:

It is the study of parasites, their hosts & the relationship between them.

One of the largest fields in parasitolgy, medical parasitology is the subhect which deals with the parasites that infect humans, the diseases caused by them, clinical picture and the response generated by humans against them. It is also concerned with the various methods of their diagnosis, treatment & finally their prevention & control.Slide4

Scientific Classification

Kingdom: Animalia

Phylum: Platyhelminthes Class: Trematoda Subclass: Digenea Order: Echinostomida Family: Fasciolidea Genus: Fasciola Species: hepaticaSlide5

TREMATODES-FLAT WORMS(FLUKES)

Opisthorchis

O. sinensisO. felineusO. viveriniParagonimus P. westermani

P.

kellicotti

E

chinostoma

Schistosoma

S.

mansoni

S.

hematobium

S.

japonicum

Fasciolopsis

Fasciolopsis

buski

Fasiola

Fasiola

hepatica

Fasiola

giganticaSlide6

Trematodes: Morphological Features

Mouth connects to pharynx, leads to esophagus, bifurcates into 2 ceca

No anus: releases cecal contents back through mouth into tissue it infectsCecal contents can be seen in histopathologic section and are colloquially referred to as “fluke puke”Also possess and acetabulum, or ventral sucker – holdfast organ not associated with feeding Near anterior end, mouth is surrounded by muscular oral suckerSlide7

Trematodes: ReproductionWith exception of schistosomes (blood flukes) all flukes are hermaphroditic

Each fluke possesses both sex organs

Self-fertilization usually takes place, but cross-fertalization can also occurSlide8

Fasciola hepatica

Fasciola hepatica

, also known as the common liver fluke or sheep liver fluke. Is a parasitic flatworm of the class Trematoda, phylum Platyhelminthes that infects liver of various mammals, including humans. The disease caused by the fluke is called fascioliasis (also known as fasciolosis). F. hepatica is world-wide distributed and causes great economic losses in sheep and cattle.Slide9

Definitive host:

Sheep

CattleHumans (Accidental)Other Mammals Intermediate host:Fresh Water Snail Geographic Range:Cosmopolitan; anywhere sheep and cattle are raisedSlide10
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Morphology of adult Fasciola hepatica

acetabulumSlide12

Morphology

:

(Angus, 1978)SpecieSizeShapeF.hepatica5cm length/1.5cm wideLeaf shape with prominent shoulders

F.gigantica

7.5cm length/1.2cm wide

Leaf shape with scarcely perceptible

shouldersSlide13

Dr.T.V.Rao MD

13Slide14

Life cycle outside the animal

Eggs hatch in spring (>10 °C) to release

miracidia which must penetrate a mud snail (Lymnaea [syn. Galba] truncatula) within 3 hours Develop inside snail Cercariae emerge from snail Encyst on grass (metacercariae) Infection of a snail with one miracidium can produce over 600 metacercariae Slide15

Life cycle inside the animal

Once ingested metacercariae excyst in SI and immature fluke migrate through the gut wall to penetrate the liver

Tunnel through liver for 6-8 weeks before entering bile ducts where they reach maturity Time from infection of cattle/sheep to adult egg-laying fluke is 10-12 weeks Little or no development of immunitySlide16

Cycle of Events in Fasciola hepatica

The life cycle of Fasciola hepatica starts when a female lays eggs in the liver of an infected human. Immature eggs are discharged in the biliary ducts and taken out in the feces. If landed in water, the eggs become embryonated and develop larvae called miracidia. A miracidium invades an aquatic snail and develops into cercaria, a larva that is capable of swimming with its large tail.

Dr.T.V.Rao MD16Slide17

The cercaria exits and finds aquatic vegetation where it forms a cyst called Metacercariae. A human eats the raw freshwater plant containing the cyst. The Metacercariae excysts in the first part of the small intestine, duodenum. It then penetrates the intestinal wall and gets into the peritoneal cavity.

Cycle of events in infection

Dr.T.V.Rao MD17Slide18

Cycle of events in infectionIt finds the liver and starts eating liver cells. This happens only a few days after the initial contact with the parasite. Usually the larva spends a few weeks just browsing and eating the liver. Then it relocates to the bile duct where it begins its final stage and becomes an adult. It takes about three months for the Metacercariae to develop into an adult. Adults are about 3 cm long and 1 cm wide. Adult females can produce up to 25000 eggs per day.

Dr.T.V.Rao MD

18Slide19

Ingestion MetacercariaeEx-cyst in DuodenumBurrows through Intestinal Wall

Enters Peritoneal Cavity

Migrates to LiverProgress of InfectionDr.T.V.Rao MD19Slide20

MACROSCOPIC & MICROSCOPIC EXAMINATIONSlide21

Egg capsule with emerging miracidium of Fasciola hepatica.  400x Slide22

F.hepatica

, egg: eggs measure 140 by 80 µm and are

operculated. The colour is yellow to brown. (Formol-ether concentration).Slide23

egg capsule with emerging miracidium

of

Fasciola hepatica

.  400x

unembryonated egg

capsule of

F. hepatica

. earlier stage of development.  400x

embryonated egg

capsule of

Fasciola hepatica. 

So-named because the

miracidium

is fully formed and ready to emerge.  The operculum can be seen to the left.  400x Slide24

Redia and cercaria of

Fasciola hepatica

Miracidium of

Fasciola hepatica

. This ciliated, non-feeding larval stage, has about 24 hours to find its specific snail host, such as

Fossaria

modicella

or

Stagnicola bulimoides. 

400x Slide25

The ova

Length 130-145 µm

Width 70-90 µm

Regular ellipse

Thin shell

Operculum at one pole

Granular yellowish-brown contents filling whole egg Slide26

The Adult

one of the largest flukes in the world.

20 -30mm in length and 13 mm in width Leaf shape characteristic with the anterior end broader than the posterior end and an anterior cone-shaped projection. Possesses a powerful oral sucker at the anterior cone and a ventral sucker at the base of the cone  attach to the lining of the biliary ducts.monoecious - possesses ovaries and testes which are highly branched and allow for individual flukes to produce eggs independently.Slide27

A stained adult

Fasciola hepatica

; approximate length = 20 mm.  The internal organs are highly branched, thus making it very difficult to differentiate the various internal organs

All of their major systems are branched, including the intestine, testes, and ovary.Slide28
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F.hepatica

,

adult worm, macroscopic examination: adults measure 2-5 cm by 8-13 mm, are flat, oval in shape with a cephalic cone containing the oral sucker.The adults live in biliary ducts for up to 10 years.

Fasciola

hepatica

, living adult in bile duct of sheep. Slide30

F.hepatica

, adult worm, liver biopsy: after

excistation in the small intestine, metacercariae penetrate the intestinal wall and the Glisson capsule, cross the liver parenchima to the bile ducts.Eggs can be found in

faeces

3-4 months after penetration.Slide31

F.hepatica

, adult worm, macroscopic

examination: higher magnification: particular of the cephalic cone with the oral sucker.Slide32

SYMPTOMS:Slide33

The first stage:

prepatent or larval period: Abdominal Pain Fever Backache, headache Chills Weight loss Urticaria Eosinophilia, elevation of AST, ALT Cough and chest discomfort

The second stage: patent or

biliary

period:

Intermittent right upper quadrant pain

Enlarged, tender liver

Diarrhea

Eosinophilia

Complications:

Anemia,

cholangitis

,

biliary

obstruction,

subcapsular

liver hematomas,

hemoperitoneum

SymptomsSlide34

Condemned Liver

Annual condemnation of livers of 3-4% of cattle at $3-5 each due to parasites

.

Adult-

Biliary

hyperplasia, dilatation, fibrosis, calcification

Migration-Diffuse fibrosis, shrunken ventral lobeSlide35

The course of infection passes through three phases:

• The

acute phase • The chronic phase • The obstructive phasePathology / clinical manifestations are related to the phaseSlide36

Acute Phase:

Rarely seen in humans and occurs only when a

large number of metacercariae are ingested at once. Fever, tender hepatomegaly, and abdominal pain are the most frequent symptoms of this stage of infection vomiting, diarrhea, urticaria (hives), anemia, may be present. Caused by the migration of the F. hepatica larvae throughout the liver parenchyma. The larvae penetrate the liver capsule and begin to produce symptoms 4-7 days after ingestion. Migration and acute phase continues for 6-8 weeks until the larvae mature and settle in the bile ducts. Slide37

The acute phase:

Coincides with migration of the immature flukes through the peritoneal cavity, penetrating liver capsule then through liver parenchyma till they reach the bile ducts.

liverSlide38

Symptoms :

Acute symptoms Asymptomatic (unusual) Severe illness (prostration & jaundice) (unusual)

Acute dyspepsia

Prolonged high fever

Hepatomegaly/ abdominal pain in the right hypochondrium

Urticaria

Peripheral eosinophilia, up to 80%

.

AnaemiaSlide39

Cont..

Chronic Phase:

more common in human include biliary cholic, abdominal pain, tender hepatomegaly, and jaundice. In children, severe anemia - common result of infectionbiliary obstruction and inflammation  caused by the presence of the large adult worms and their metabolic waste in the bile ducts. Inflammation of the bile ducts  leads to fibrosis and a condition called "pipestem liver", (white appearance of the biliary ducts after fibrosis). The final outcome  portal cirrhosis and even death.Slide40

The

chronic

phase, coincides with the presence of the flukes in the bile ducts The life span of the parasite is 10-13 yearsPathology tends to be mildSlide41

Symptoms

: Asymptomatic Few gastrointestinal symptoms Intermittent fever with persistent prominent eosinophilia Recurrences of the acute signs & symptoms Recurrent cholangitis Slide42

Obstructive phase

(heavy / prolonged infection) Coincides with epithelial changes in the bile ducts due to irritation of the epithelium by the spines& the activity of proline Slide43

Diagnosis

Fasciola

is diagnosed by fecal sedimentation examinationEggs are large, operculated and golden in colorSlide44

DIAGNOSIS:Slide45

Laboratory diagnosis

The definitive and most widely used form of diagnosis is the directly observed presence of Fasciola hepatica eggs either in a

stool sample, duodenal aspirate or biliary aspirate. However, the flukes do not begin to produce eggs until roughly 4 months after infection. Until this time and in the case of ectopic infections where eggs are not present in the stool, serological tests can be used, the FAST-ELISA being the most popular. It has a sensitivity of 95% and can detect specific F. hepatic antibodies as early as 2 weeks after infection .Ultrasound can be used to visualize the adult flukes in the bile ducts CT scan may reveal the burrow tracts made by the worms and dilation of the bile ducts. Slide46

Computed tomography (CT) and magnetic-resonance-imaging (MRI)are used for further characterization of the

lesion.They

are indispensable for the evaluation of extrahepatic affection in AE and they are used for a preoperative evaluation.CT best depicts the typical calcifications and it is used for follow-up examinations at longer intervalls. For serology an ELISA was established based on the purified E.multilocularis carbohydrate antigen Em2 (derived from the laminated layer). It is the reference test for diagnosis and it may allow discrimination of AE from E.granulosus infection.However, in a significant percentage of cases the two species can not be differentiated simply by serological means. Slide47

Halzoun

: worm

settles in the pharynx. Occurs when an individual consumes infected raw liver  The young adult worms then attach themselves to the pharyngeal mucosa  causes considerable pain, edema, and bleeding that can interfere with respiration. The adults can live in the biliary ducts, causing symptoms for up to 10 years. Ectopic Infection: Ectopic infections through normal transmission are infrequent but can occur in the peritoneal cavity, intestinal wall, lungs, subcutaneous tissue, and very rarely in other locations.Slide48

Fasciola

hepatica:

although direct diagnosis by observation of eggs in faecal smears it the reference method, indirect diagnostic tests such as IF may allow diagnosis when direct observation is negative. Immunodiagnosis by indirect mmunofluorescence.

Antigen: frozen sections of

Fasciola

hepatica.

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epidemiology

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Infection begins when Metacercariae infected aquatic vegetation is eaten or when water containing Metacercariae is drunk. Humans are often infected by eating watercress. Human infections occur in parts of Europe, northern Africa, Cuba, South America, and other locales. It is one of the most important disease agents of domestic stock throughout the world and shows promise of remaining so for years to come.Slide50

Treatment

Bithional

Highly EffectiveLarge DoseHigh CostLong Treatment PeriodTriclabendazoleEasier to Use1-2 Oral Doses in 24 hrsVirtually 100% EffectiveSurgery50Slide51

Prevention

The presence of a substantial reservoir

- keep domestic animal herds separate from the growing sites of aquatic. This limits the risk of contaminating the vegetation and thus decreases both human infection and the animal reservoirThe presence of the intermediate host, the Lymanaea snails - application of molluscicides to decrease the population of Lymnaea snails.The opportunity for water source contamination by human and non-human hosts Dietary practices that include the consumption of raw, untreated aquatic vegetation.Slide52
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References:www.slideshare.net