Fasciola hepatica also
called (Liver fluke) is a parasitic disease caused by infection of trematode
belongs to genus (F. hepatica, F. gigentica). Fasciola hepatica is distributed worldwide
and cause great economic loss in livestock sector. Infected animal become
anemic and loss of significant amount of weight.
Fasciola hepatica is mainly found in hilly area and F. gigentica is mainly found in planes area and restricted to warmer region.
Definitive host: sheep/ cattle, human (Accidental)
Intermediate host:
fresh water snail (genus: Lymnaea)
- The common species of trematode are:
- Fasciola hepatica (liver fluke)
- Fasciola gigentica (liver fluke)
- Fasciolopsis buski (intestinal fluke)
- Fasciola indica (liver fluke)
- Paramphistome cervi ( stomach fluke)
- Schistosomiasis (Nasal granuloma)
How animal infected by F.
hepatica?
When heavy rain or flood in rainy season, the pasture is heavily contaminated encyst cercariae. Snail are the intermediate host and multiply very rapidly in water. The animal are attracted by lush, green grasses around the pond, stream and other water sources full of snail and get themselves infected.
Life cycle of liver
fluke:
- The
lifecycle of F.hepatica start when a female laid egg in the liver of infected
animals.
- Immature
egg are discharge in the billary duct and taken out in the feces.
- If
they landed in water, the egg become embryonated and develop larvae called miracidium.
- Meracidium
find its host which is snail and convert into sporocyst, rediae, and cercariae
in snail.( larvae which is capable of swimming with its large tail).
- Cercariae
should be converted into metacercariae and this metacercariae through
vegetation ingested by cattle, goat, sheep and other host.
- Then metacercariae goes into the first part of small intestine, duodenum. Then it’s penetrated the intestinal wall and gets into peritoneal cavity and the larva goes into the liver.
- And start to eating liver cell. Usually the larvae spent a few weeks just browsing and eating the liver. It takes about 3 month for metacercariae to develop into adult.
Clinical sign and
symptoms:
F. hepatica is a zoonotic
disease. The clinical sign include high fever, profuse diarrhea, loss of
weight, sub mandibular edema (bottle jaw), pale mucus membrane, anemic
condition, reduce milk production, poor fertility and debilitation.
Acute fascioliasis: This stage is mostly common in sheep and goat but not common in cattle and other large animal. Lack of appetite, weakness, edema of mucosa and conjunctiva are common sign of this stage. Also cause traumatic hepatitis, and fibrosis clot on liver surface is seen, liver enlarge.
Chronic fascioliasis: in this stage, this is most common type of fascioliasis which is found in all type of animal of all age including man also. Sign include, anemic with rough andoffcoloured skin coat. Mucus membrane becomes pale and skin become dry, sub mandibular edema (bottle jaw), milk production decrease and chronic diarrhea may occur.
Fig:1. Profuse diarrhea in goat
Fig:3. Pale mucus membrane
Fig:5. Administer fluid therapy
Diagnosis:
Generally F. hepatica is
diagnosis by fecal test, such as sedimentation or centrifugation for the
detection of egg.
It also depends on the history of snail habitat or fascioliasis on the farm, clinical symptoms, post mortem examination, blood examination etc.
Fig: 6. Fasciola hepatica Fig:7. Fasciola buski
Treatment and prevention:
Albendazole
7.5 mg /kg bwt in small animal and 10 mg/kg bwt large animal is effective
against adult flukes.
Prevention:
. As we know that snail is intermediate host so that infective stage of snail is meracidium and infective stage for final host is metacercariae. So if we break the cycle of these 2 stages so that we can prevent this disease.
Control the population of snail.
Use deworming regularly.
. It is essential to remove animal form infected pasture. They should not be allowed to graze on flood inundated pasture.
Author: Dr. Manoj karki (BVSC&AH)
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