Details of classification, management and treatment of fasciolasis, life cycle, life style management prepared by RWAPEMBE STEPHEN

1. MICROBIOLOGY
GENUS FASCIOLA
BY
RWAPEMBE STEPEHN
2022/U/MMU/BNSD/003

2. INTRODUCTION
Fasciola hepatica (liver fluke) is
a platyhelminth (flatworm) that is bilaterally
symmetrical, triploblastic and dorso-ventrally
flattened. They are unsegmented and
acoelomates. They are trematodes belonging to
subclass digenea. Thus, they are endoparasites
with two suckers without hooks.

3. STRUCTURE

4. CLASSFICATION
KINGDOM ANIMALIA
PHYLUM PLATYHELMINTHES
CLASS TREMATODA
SUBCLASS DIGENEA
ORDER ECHINOSTOMIDA
GENUS FACIOLA
SPECIES HEPATICA

5. GENERAL CHARACTEISTICS
Fasciola hepatica is found in the bile duct of sheep’s
liver as an endoparasite.
The body is dorso-ventrally flattened, leaf-like and
measures about 25-30 mm in length and 4-5 mm in
breadth.
The anterior end is produced into a conical
projection called the cephalic cone.
The mouth is situated ventrally at the anterior end,
and it is surrounded by oral sucker
A highly muscular ventral sucker or acetabulum is
situated a little posterior to the oral sucker.

6. The posterior end is large and more rounded
in the front than the back.
The digestive system comprises oesophagus,
pharynx and diverticulated intestine.
The excretory pore is situated at the posterior
extremity.
They are hermaphrodites, i.e, they have both
female and male reproductive parts.
The eggs pass to the exterior through the
median genital pore present between the
ventral and oral suckers.

7. LIFE CYCLE OF FASCIOLA
People most commonly get infected with liver
flukes through the following ways:
consuming freshwater fish infested with the
flukes
eating freshwater vegetables, such as
watercress
drinking contaminated water
washing vegetables or fruits with
contaminated water

8. STAGES OF DEVELOPMENT AND LIFE CYCLE
1) The Egg – Stage 1 –
The adult female liver fluke parasite passes
immature eggs in the bile duct and comes out
into the environment through the faeces. If and
when the eggs come in contact with water, the
eggs become embryonated and form into a
larva called miracidia.

9. 2) The Intermediate Host
A miracidia larva infects a snail and the miracidia
larva transforms into cercaria larvae. Here, the
snail acts as an intermediate host and the cercaria
larvae have a long tail that helps them swim in the
water. The cercaria larva grows, leaves the snail
host and looks for vegetation, where it forms cysts
called metacercariae. Metacercariae is the
infective stage in animals like sheep and cattle
and in human beings.

10. Metacercariae have a rigid hard outer layer,
which helps them live for longer periods of
time. When human beings consume
contaminated water or fish contaminated with
cysts, the cysts release immature eggs into the
small intestine of the human host.

11. 3) The Young Fluke – Stage 3 –
The fluke parasite penetrates the small
intestinal wall and enters the peritoneal cavity.
After this, it enters the liver and the parasite
starts feeding on liver cells. This occurs a few
days after the host comes in contact with the
parasite. After eating plenty of liver cells, the
young flukes migrate to the bile duct and
transform into adult liver flukes.

12. 4) The Adult – Stage 4 –
The metacercariae transform into an adult liver
fluke parasite after around three months. An
adult liver fluke measures up to 3 cm in length.
A gravid adult female liver fluke can produce
20,000 to 25,000 eggs per day.

14. DISEASE CAUSED AND TYPES OF FASCIOLA
The scientific name for liver flukes
is Fasciola, and the disease they cause is
called fascioliasis.
The Centers for Disease Control and
Prevention (CDC) have identified two types of
liver flukes that can infect people: Fasciola
hepatica and Fasciola gigantica.

15. CLINICAL MANIFESTATIONS
Nausea
Vomiting
Abdominal pain
Diarrhea
Vomiting
Weight loss
Hives
Fever
Malaise
Pancreatitis

16. Diagnosis
Microscopic examination of stool or duodenal
or biliary material for eggs
Antibody assays

17. Prevention
cooking all vegetables grown near cattle and
sheep
cooking animal livers and not consuming them
raw
boiling all untreated water
not drinking water directly from a stream near
where cattle and sheep live

18. Controll
No vaccine exists for fasciolasis
Treatment of fascioliasis for patients ≥ 6 years
of age is with 2 doses of 10
mg/kg triclabendazole given 12 hours apart,
orally with food.
Nitazoxanide 500 mg orally twice a day for 7
days may be effective.
Praziquantel 25 mg/kg orally 3 times a day for 1
day..

19. REFERENCES
Fürst T, Keiser J, Utzinger J. Global burden of human
food-borne trematodiasis: a systematic review and
meta-analysis. The Lancet Infectious Diseases.
2012;12(3):210–221. PubMed Web of Science
®Google Scholar
McNulty SN, Tort JF, Rinaldi G, et al. Genomes of
Fasciola hepatica from the Americas reveal
colonization with neorickettsia endobacteria related to
the agents of potomac horse and human sennetsu
fevers. PLoS Genet. 2017;13(1):e1006537.
PubMed Web of Science ®Google Scholar