Flukes (Trematodes) 1-2

Front 1

Class of Flukes? Phylum?

Back 1

Class = TREMATODA

Phylum = PLATYHELMINTHES

Front 2

Fasciola hepatica - Final host? IMH? Significant in what species? Disease? Zoonotic?

Back 2

Final host = Most mammals

IMH = Galba truncatula (Amphibious small brown snail)

Significance = CATTLE & SHEEP

Disease = Fasciolosis

Zoonotic = Yes! Can cause severe illness in man!

Front 3

Where are the adult fasciola hepatica located?

Back 3

BILE DUCTS (Gall bladder)

Front 4

Leaf-shaped trematodes with oral sucker and a central sucker.

Back 4

FASCIOLA HEPATICA

Front 5

Describe the life cycle of liver fluke (fasciola hepatica):

Back 5

1. Eggs passed in feces (yellow, tannish color), but need to embryonate before infective

2. Embryonation occurs in about 9 days; required temps ~22C & light for hatching into infective miracidium.

3. Miracidium penetrates mud snail (Galba truncatula); requires watery environment for motility toward snail

4. Miracidium sporocysts to redia after about 6-7 weeks in the snail (multiplies x600 in the snai= pedogenesis)

5. Light, warmth and rainwater triggers the fluke to leave the snail in Cercaria form

6. Cercaria transforms to resistant metacercaria form and encysts on grass, awaiting to be ingested by a grazing mammal

7. Once ingested, excystation is induced by CO2 and bile, juvenile flukes in liver parenchyma 6-8 weeks & adults mature in bile ducts by 4 weeks.

* PPP = 10-12 weeks

Front 6

Pathogenesis of acute, subacute and chronic fasciolosis?

Back 6

** ACUTE FASCIOLOSIS

2-6 weeks post ingestion of >2000 metacercariae

* Detected autumn/early winter

CAUSED BY: Migration of juvenile flukes

RESULTS IN: Liver damage and hemorrhage

CLINICAL SIGNS: sudden death, weak animals with pale mucous membranes, dyspnoea, palpable liver, ascites, abdominal pain

** SUBACUTE FASCIOLOSIS:

6-10 weeks post ingestion of 500-1500 metacercariae

CAUSED BY: Juveniles migrating & ADULTS IN BILE DUCTS (feed on blood and damage biliary mucosa, inducing inflammation)

RESULTS IN: Liver damage (parenchyma, plus cholangitis), bile ducts & blood loss

CLINICAL SIGNS: Rapid/severe hemorrhagic anemia with hypoalbuminemia, pale mucous membrane, enlarged liver, some edema or ascites

** CHRONIC FASCIOLOSIS

4-5 months post ingestion of 200-500 metacarcariae

CAUSED BY: Adults feeding in bile ducts

RESULTS IN: Anemia, hypoalbuminemia, cholangitis

CLINICAL SIGNS: Progressive loss of condition, emaciation, pale mucous membranes, submandibular edema ("Bottle jaw"), ascites

Front 7

Acute fasciolosis disease symptoms caused by . . .? Results in? Clinical signs?

Back 7

CAUSED BY: Migration of juvenile flukes

RESULTS IN: Liver damage and hemorrhage

CLINICAL SIGNS: sudden death, weak animals with pale mucous membranes, dyspnoea, palpable liver, ascites, abdominal pain

Front 8

Describe a PM Liver of an animal who suffered with acute fasciolosis.

Back 8

- Enlarged hemorrhagic liver

- Rupture of sub-capsular hemorrhages

- Fibrinous exudate build up on fascia

- Necrotic migration tracks of juvenile flukes

Front 9

Chronic parasitic disease resulting in productivity loss, calcification of bile ducts and gall bladder enlargement.

Back 9

BOVINE FASCIOLOSIS (liver fluke; fasciola hepatica)

- Immune response limits primary infection & inhibits secondary infection

Front 10

How would you diagnose liver fluke in ovine? Bovine?

Back 10

OVINE:

- Clinical signs/seasonal occurrence

- Eggs in feces

- PM & identification of flukes

BOVINE:

- Eggs in feces

- Test for glutamate dehydrogenase

- Y glutamyl transpeptidase

- ELISA

* Same parasite causing disease in sheep and cattle

Front 11

Describe the epidemiology of fasciolosis (fasciola hepatica).

Back 11

SUMMER infection of snail (galba truncincta):

Optimal period for snail development/parasite development is MAY-OCT (snail breeding season)

- Snails infected by miracidia in late Spring/Summer, derived from overwintered eggs or eggs passed in feces of hosts

- Inc metacercariae on pasture Aug-Oct

WINTER infection of snail (less imp):

- Snails infected by miracidia in Autumn

- Conditions sub-optimal & development stops over winter, and resumes in Spring

- Metacercariae produced May-June

Front 12

Liver fluke infections in sheep have been rising each year.

True or False?

Back 12

TRUE

Front 13

Treatment protocols for Acute Fasciolosis? Subacute? Chronic?

Back 13

ACUTE = Dose with Triclabendazole & move to clean pasture!

SUBACUTE = Closantel, Nitroxynil dose & move to clean pasture

CHRONIC = range of drugs can be given but should rotate to avoid further resistance.

Front 14

Faciola hepatica resistance to ___________________ has been shown in Scotland and Whales.

Back 14

TRICLABENDAZOLE

Front 15

Control methods for fasciola hepatica?

Back 15

- Drainage of fields

- Fence off saturated pasture

- Move sheep to drier pasture when under threat

- Treat & quarantine new arrivals

- Prophylactic use of anthelmintics (dose in Oct & Jan)

Front 16

What are the four fluke families of major importance?

Back 16

1. Fasciolidae

- Fasciola hepatica, giagantica

2. Dicrocoeliidae

3. Paramphistomatidae

4. Schistosomatidae

Front 17

Fasciola gigantica distribution?

Back 17

Tropical & Sub-tropical regions (Africa, S Asia)

Front 18

Differences between Fasciola gigantica and hepatica?

Back 18

F. GIGANTICA

- Much bigger (75mm) compared to F. Hepatica (30mm)

- More pathogenic

- IMH are AQUATIC SNAILS (not amphibious)

Front 19

Epidemiology of F. gigantica?

Back 19

- Miracidia = hatch at beginning of wet season, infect snails & develop by the end of wet season

- Cercaria = shed from snail at beginning/during dry season

- Metacercaria = encyst on AQUATIC plants or in water

- Disease symptoms = end of dry season or beginning of next wet season

Front 20

PPP of F. gigantica?

Back 20

PPP = 13-16 weeks

Front 21

Control of F. Gigantica?

Back 21

1. ANTHELMINTICS - similar to F. hepatica

2. Snail control

- Fencing permanent water sources

- Pump water to troughs

Front 22

Dicrocoelium dendriticum distribution? Hosts? IMH? Predilection site?

Back 22

DISTRIBUTION: Worldwide (Europe, UK, USA)

MAIN HOSTS: Sheep, cattle, horses, & rabbits

IMH: Land snails & ants

PREDILECTION SITES: Bile ducts & gall bladder

Front 23

Lice cycle of dicrocoelium dendriticum?

Back 23

1. Yellow, brown egg is fully embryonated when laid.

2. Snails eat the eggs and once inside the snail, the eggs hatch.

3. Cercariae ejected with slimeball release from snail

4. Slimeballs eaten by ants and the metacercariae encysts in abdomen of ant

5. Then moves to the brain of the ant and controls it to move to the ends of grass, ready to be eaten by host mammal = ENSLAVER PARASITE

6. Within the host mammal, excystation in duodenum and migrate to liver via bile duct

7. In bile ducts, fluke develop to adults, begin reproducing and perpetuating the cycle.

Front 24

Pathogenesis of Dicrocoelium dendriticum results in heavy infections of older sheep. Clinical signs? PM signs?

Back 24

CLINICAL SIGNS:

- Weakness

- Anemia

- Emaciation

- Productivity losses (dec wool production, premature aging, repro losses)

PM SIGNS:

- Fibrosis of & distended bile ducts

- Progressive cirrhosis

Front 25

Treatment of dicrocoelium dendriticum?

Back 25

ALBENDAZOLE

Front 26

Conical, maggot-shaped flukes of ruminant rumens.

Back 26

PARAMPHISTOMATIDAE (Rumen fluke)

- Paramphistomum cervi & P. microbothrium

Front 27

Paramphistomes distribution? Hosts? IMH? Cause of pathology?

Back 27

DISTRIBUTION: Tropics, sub-tropics, S USA, emerging in UK

HOST: Ruminants

IMH: Aquatic snails

CAUSE OF PATHOLOGY: Juveniles, attach to mucosa of rumen (plug feeders)

Front 28

Life cycle of paramphistomums?

Back 28

Snail stages same as Fasciola species

- Metacercaria are ingested

- Excyt in duodenum where juveniles attach to intestinal wall and feed (6 weeks)

- Adults migrate to forestomach and reproduce

PPP = 7-10 weeks

Front 29

Pathogenesis of paramphistomums?

Back 29

Juveniles attach to mucosa of duodenum, causing intestinal infection

- Causes necrosis and hemorrhage/erosion of duodenal mucosa

- Results in gastroenteritis causing clinical signs of edema, hemorrhage, & ulceration

- Adults cause little harm

Front 30

Clinical signs of paramphistomes?

Back 30

- Fetid diarrhea (smelly)

- Anemia & Hypoalbuminemia

- Intense thirst & anorexia

- Potential for high mortality

Front 31

Diagnosis of paramphistomes? Treatment?

Back 31

DIAGNOSIS:

- PM (juveniles in duodenum)

- FEC = limited value

TREATMENT:

- OXYCYLOZANIDE

Front 32

SCHISTOSOMATIDAE major species? distribution? Hosts? IMH?

Back 32

MAJOR SPECIES:

- Schistosoma bovis, S. japonicum & S. matthei

DISTRIBUTION:

Tropics, subtropics & S. Europe

HOSTS:

- All domestic mammals, cattle and sheep

IMH:

Aquatic snails

Front 33

Life cycle of schistosomes?

Back 33

1. Eggs shed in feces

2. As soon as eggs touch water, miracidia emerge and infect snails

3. WIthin the snails transform from sporocyst to cercariae, which emerge from the snail.

4. Cercariae then attack skin of host mammal & within 15 minutes enter the blood circulation of the host mammal

5. Enter lymph glands and continue to circulate around the heart, lungs and liver

6. Eggs laid in mesenteric vessels and eventually tear through the BVs and into the gut cavity to be passed in feces

Front 34

Inflammatory response against eggs in veins, mucosa and liver, which lead to granuloma formation on intestinal mucosa and liver - Which parasite pathogenesis is this?

Back 34

SCHISTOSOMA

Front 35

ACUTE VS CHRONIC SCHISTOSOMA PATHOGENESIS?

Back 35

ACUTE:

- Mucosal hemorrhage, anemia, hypoalbuminemia & hepatosplenomegaly

- Clinical signs: diarrhea (mucous & bloody), thirst, anorexia, emaciation

CHRONIC:

- Marked granuloma of intestine & cirrhosis/periportal fibrosis of liver

- Reduced productivity

Front 36

Diagnosis of schistosoma infection?

Back 36

- Eggs in feces

- Clinical signs/infected water source (coupled to demonstration of granulomatous lesions and adults in mesenteric veins)

Front 37

Epidemiology, control and treatment of schistosomas?

Back 37

EPIDEMIOLOGY:

- Related to prevalence of aquatic snails

CONTROL:

- Clean water source available

- Controlled movement of cattle

TREATMENT:

- Praziquantel, albendazole