Liver fluke: Introduction, Classification, Fasciolasis Symptoms, Diagnosis

Liver Fluke: Introduction, Classification, Fasciolasis Symptoms, Diagnosis, Treatment and Prevention

Liver Fluke Introduction

Liver fluke is common of Fasciola hepatica and adult worm encountered during performing ERCP as shown above picture. Fascioliasis is a parasitic infection typically caused by Fasciola hepatica, which is also known as “the common liver fluke” or “the sheep liver fluke.” A related parasite, Fasciola gigantica, also can infect people. Fascioliasis is found in all continents except Antarctica, in over 70 countries, especially where there are sheep or cattle. People usually become infected by eating raw watercress or other water plants contaminated with immature parasite larvae. The young worms move through the intestinal wall, the abdominal cavity, and the liver tissue, into the bile ducts, where they develop into mature adult flukes that produce eggs. The pathology typically is most pronounced in the bile ducts and liver. Fasciola infection is both treatable and preventable

Classification of Fasciola hepatica

Kingdom: Animalia
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Rhabditophora
Clade: Trematoda
Clade: Digenea
Order: Plagiorchiida
Suborder: Echinostomata
Superfamily: Echinostomatoidea
Family: Fasciolidae
Genus: Fasciola
Species: F. hepatica

Mode of Transmission of Liver Fluke

Ingestion of freshwater plants with metacercaria or by drinking water with floating metacercariae.

Diagnostic Stage: Ova

Infective Stage: Metacercaria

Pathogenicity and Clinical Features

It causes zoonotic disease fascioliasis. After the larvae are ingested with contaminated food or water, a symptom-less incubation period starts, lasting for a few days to a few months. The disease may be in the following phases acute or invasive phase and Chronic or latent phase.

Asymptomatic phase

It can cause fever.
Right upper quadrant abdominal pain
Hypereosinophilia

Acute or invasive phase

The acute phase, lasting 2-4 months.
Migration from the intestine to the liver
Traumatic and necrotic lesions in liver parenchyma

Chronic or latent phase

The parasite has reached the bile ducts
Obstruction
Stimulates inflammation in the biliary epithelium leading to fibrosis
Obstruction causes biliary sepsis

Symptoms of Fascioliasis

Fascioliasis is mainly an infection of the bile ducts and liver, but infection can also occur in other parts of the body.

nausea
vomiting
abdominal pain/tenderness
Fever,
rash,
difficulty in breathing
inflammation and blockage of bile ducts
Inflammation of the gallbladder and pancreas also can occur.

Laboratory Diagnosis of Liver Fluke

Specimens- Stool, duodenal or biliary aspirates, blood

Microscopy: Demonstration of eggs in the feces.

Serological test: testing using an immunoblot assay that detects IgG antibody to FhSAP2, a recombinant antigen derived from Fasciola hepatica.

Molecular test: RFLP(restriction Fragment Length Polymorphism ): PCR-RFLP, is a technique that exploits variations in homologous DNA sequences. It refers to a difference between samples of homologous DNA molecules that come from differing locations of restriction enzyme sites, and to a related laboratory technique by which these segments can be illustrated.

Complete blood cell (CBC) count and biochemical test: Eosinophilia and abnormal liver function test parameters

Additional types of testing: Abdominal imaging, such as USG, computerized axial tomography (CAT scan), magnetic resonance imaging (MRI) scan, and endoscopic retrograde cholangiopancreatography (ERCP as shown below); and histopathologic examination of a biopsy specimen of liver or other pertinent tissue.

Treatment of Liver Fluke

The drug of choice for the treatment of fascioliasis is Triclabendazole, a benzimidazole compound active against immature and adult Fasciola parasites. The recommended due to having following properties-

Efficacy
Safety
Ease of use

Other drugs are-

Bithionol
Nitazoxanide

Note-Praziquantel, which is active against most trematodes (flukes), typically is not active against Fasciola parasites, and therefore, praziquantel therapy is not recommended for fascioliasis.

In some patients who have biliary tract obstruction, manual extraction of adult flukes e.g., via endoscopic retrograde cholangiopancreatography (ERCP) may be indicated as shown below-

Epidemiology

They are worldwide distribution in distribution and economic importance in livestock raising. Few human cases have been reported locally.

Prevention of Liver Fluke

The prevention can be achieved by using the following steps-

Inspecting the plants, especially watercress, very carefully for the metacercariae or more effectively by not eating plants grown in areas where herbivorous mammals (especially sheep) are found.
The contamination of water with feces from infected animals or people in areas where the aquatic plants are used for food should be prevented.
Water-grown vegetables should be washed with 6% vinegar or potassium permanganate( KMnO4) for 5-10 minutes, which kills the encysted metacercariae.
This approach is more successful than attempts to halt the consumption of raw vegetables.
Cook water-grown vegetables thoroughly before eating.
Avoid sewage contamination of growing areas.
The use of molluscicides is the most frequent public health intervention, as it prevents the transmission of many other trematodes, including Schistosoma species.

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