Platyhelminths - Fascioliosis

Question 1

Lifecycle of fasciola

Answer 1

Question 2

Fasciola species

Answer 2

F. hepatica - worldwide (SI, ruminants)

F. gigantica - Asia/Africa (SI, ruminants)

F. magna - USA/parts of Europe (deer)

Question 3

Fasciola snail IH

Answer 3

Lymnaeidae

Question 4

Morphology of Fasciola hepatica

Answer 4

• Large (1-3cm), leaf like, broad
• Anterior end broader
• highly branched caeca
• spines on tegument

Question 5

Whaich fasciola?

Answer 5

F. gigantica

Question 6

What is this?

Answer 6

Lymnaea tomentosa

Question 7

Common features of Lymnaea

Answer 7

• clockwise spiral
• no operculum
• Tentacles flat and triangular
• Length of shell 4-12cm (cometimes 10-25cm in lessoni)

Question 8

Pathogensis of F. heapatica

Answer 8

Metacercariae ingested on plant near water

► Juvenile flukes penetrate intestinal wall to peritoneal cavity (24hrs) -> penetrate liver capsule -> migrate through liver (destruction/bleeding)

► Adult flukes establish in bile ducts and cause fibrosis -> hypertrophy of bile duct epithelium, calcification of parasites & bile stones

Question 10

Acute/subactute phase of F. hepatica

Answer 10

• 4-6 weeks

Sheep > cattle

Massive intake of metacercariae (500-200)

Traumatic hepatitis, haemorrhage -> predispose to black disease by making room for clostridium novyi -> toxaemia -> black disease

• anaemia, abdominal pain, sudden death

Question 11

Chronic phase of F. hepatica

Answer 11

>>> 6 weeks

PPP ~ 3 months

Cattle > Sheep

Cirrhosis of liver

Biliary calcification

• anaemia, bottle jaw/ ascites, diarrhoea, wasting
• hypoalbuminaemia

Question 13

Acute findings of F. hepatica on PM

Answer 13

Liver is swollen, harmorrhagic, friable,

Question 14

Subacute liver features

Answer 14

Atrophy, repair and regeneration -> cirrosis and adhesions

Question 15

Diagnosis of actute fasciolasis

Answer 15

Necropsy

Swollen, haemorrhagic, friable, rounded, pale +/- fibrosed liver

• Take a cross section -> worm without coelon

Histology -> haemorrhade, evidence of black disease

• no eggs is faeces and no adults

Question 16

Diagnsis of chronic fascioliasis

Answer 16

• Faecal float (heavy eggs)

sedementation - eggs are large, tan and have operculum

serology - look for IgG (4-6 weeks sheep, 6-8 weeks cattle)

Biochem/CBC

• anaemia, hypoproteinemia, elevated liver enzymes

Question 17

Economic significance of F. hepatica

Answer 17

• Production loss - $60-80 million p.a.
• reduced production and quality of wool, low lambing rates, poor growth and feed conversion, sudden death
• Drenching cost $10 million
• Condemnation of liver

Question 18

Epidemiology of F. hepatica

Answer 18

• Parasite, snail + rainfall (> 50 mm) + temp >10 degrees
• Freshwater, shallow, stagnant, pond, trickle stream, irrigatiojn channels
• in all states but WA and NT

Question 19

Epidemiology -> pathogenesis in temperate climate zone

Answer 19

Eggs hatch and develop to miracidium mid Septepmber -> snail (-> cercariae) takes 2 months. By mid Novemeber start getting infections -> acute fasciolisis in sheep 4-6 weeks and cattle 6-8 weeks later.

-get deaths in Jan

Question 20

Grazing habits-> disease

Answer 20

In winter rainfall areas snails breed and egg hatching in spring & early summer, get metacercariae early to mid Dec

Sheep graze near water in summer.

Question 21

Treatment of fascioliasis

Answer 21

** Trichabendazon is the only drug that kills flukes as young as 2 weeks of age, specific to liver fluke, but resistance developing, only use when needed. Give just before they carc it in late Dec/Jan

Mid summer and autumn to get the adults

Closantel (also used in haemonchus) plus oxfendazole or albendazole get flukes 6 weeks of age.

Other drugs do adult flukes.

Oxycyclozanide with levamisol for dairy

Question 22

How to control fasciola?

Answer 22

Environment - fence off snail prone areas

• drain marshy pastures
• build dams

Strategic flukicidal treatment

5-in-1 vaccine

Question 23

Lifecycle of Fasciolopsis buski?

Answer 23