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Fascioliasis: Causative agent, Life cycle, Symptoms, Treatment.

Fascioliasis is an infectious disease caused by Fasciola parasites, which are flatworms referred to as liver flukes. The adult (mature) flukes are found in the bile ducts and liver of infected people and animals, such as sheep and cattle. In general, fascioliasis is more common in livestock and other animals than in people.

What is fascioliasis?

Fascioliasis is an infectious disease caused by Fasciola parasites, which are flatworms referred to as liver flukes. The adult (mature) flukes are found in the bile ducts and liver of infected people and animals, such as sheep and cattle. In general, fascioliasis is more common in livestock and other animals than in people.

  • This infection is caused by Fasciola hepatica as well as by Fasciola gigantica. They are also termed “the common liver fluke” and “the sheep liver fluke.”
  • More than 70 countries are affected by this infectious disease where mainly sheep or cattle are reared. Fasciola hepatica can be found in all continents except Antarctica, while Fasciola gigantica has been found in some tropical areas.
  • These causative agents cause infection when an individual accidentally ingests (swallowing) parasite contaminated foods or raw watercress or other contaminated freshwater plants. 
  • This infection does not spread from person to person.
  • It is a plant originating from trematode zoonosis and is grouped as a neglected tropical disease (NTD).
  • This pathogen can infect humans as well as ruminants such as cattle and sheep.
  • Fascioliasis developed in 4 distinct phase such as;
    • An initial incubation phase, it takes time a few days up to three months and develops little or no symptoms.
    • An invasive or acute phase,  in this phase different symptoms, are developed such as fever, malaise, abdominal pain, gastrointestinal symptoms, urticaria, anemia, jaundice, and respiratory symptoms.
    • Latent phase, with fewer symptoms.
    • Chronic or obstructive phase, develop after a month to years later of Latent phase. In this phase, inflammation occurs in bile ducts, gall bladder and may lead to gallstones as well as fibrosis.
  • The death rate is significant in both cattle (67.55%) and goats (24.61%), but generally low among humans.

Causative Agent of Fascioliasis

Morphology of Fasciola

Scientific Classification

KingdomAnimalia
PhylumPlatyhelminthes
ClassTrematoda
SubclassDigenea
OrderEchinostomida
FamilyFasciolidea
GenusFasciola
SpeciesFasciola hepatica

Epidemiology of Fasciola

Transmission of Fascioliasis

Host/Reservoir of Fascioliasis

Fascioliasis life cycle/ Pathogenesis of fascioliasis

  1. First of all the immature eggs are released in the biliary ducts and passed in the stool.
  2. In freshwater, it becomes embryonated which takes over ~2 weeks.
  3. Now, these embryonated eggs release miracidia within the water.
  4. These released miracidia invade within a suitable snail intermediate host.
  5. After the invasion, the parasites undergo different developmental stages such as; sporocysts, rediae, cercariae.
  6. The snail discharged the cercariae and encyst as metacercariae on aquatic vegetation or other substrates.
  7. When a human or other mammals ingest this metacercariae-contaminated vegetation they got infected(e.g., watercress).
  8. After ingestion, the metacercariae excyst in the duodenum and enter through the intestinal wall into the peritoneal cavity. 
  9. The young flukes then through the liver parenchyma into biliary ducts, where they develop into adult flukes and produce eggs.
  10. In humans, maturation from metacercariae into adult flukes normally takes about 3–4 months. The development of F. gigantica may take somewhat longer than F. hepatica.

Fascioliasis symptoms

In most cases this infection is asymptomatic, but the symptoms can appear from a few days to several years after infection. Some common symptoms are Fever [usually the first symptom of the disease; 40–42 °C (104–108 °F)]; Abdominal pain; Gastrointestinal disturbances: loss of appetite, flatulence, nausea, diarrhea; Urticaria; Respiratory symptoms (very rare): cough, dyspnoea, chest pain, hemoptysis; Hepatomegaly and splenomegaly; Ascites; Anaemia; Jaundice.

The symptoms of Fascioliasis appears in the following phases;

Acute Phase

Chronic Phase ­

Halzoun 

Ectopic Infection

Diagnosis of Fascioliasis

Fascioliasis treatment

Fascioliasis Prevention and Control

Currently, there is no vaccine developed against Fascioliasis infection.

References

  • http://web.stanford.edu/class/humbio103/ParaSites2001/fascioliasis/Fasciola.htm#:~:text=Morphology%3A,an%20anterior%20cone%2Dshaped%20projection.
  • https://en.wikipedia.org/wiki/Fasciolosis#Cause
  • https://www.cdc.gov/parasites/fasciola/prevent.html

Citation

APA

MN Editors. (May 11, 2021).Fascioliasis: Causative agent, Life cycle, Symptoms, Treatment.. Retrieved from https://microbiologynote.com/fascioliasis-causative-agent-life-cycle-symptoms-treatment/

MLA

MN Editors. "Fascioliasis: Causative agent, Life cycle, Symptoms, Treatment.." Microbiology Note, Microbiologynote.com, May 11, 2021.

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