Fascioliasis Definition Etiology

1. Name – Alok Kumar
Grp – 09
Sem – 09
Topic - Fascioliasis

2. Definition
 Fascioliasis is an infectious disease caused by Fasciola parasites, which are flat worms
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.
 Two Fasciola species (types) infect people. The main species is Fasciola hepatica, which is

3. How do people get infected
with Fasciola?
 People get infected by accidentally ingesting (swallowing) the parasite. The
main way this happens is by eating raw watercress or other contaminated
freshwater plants. People also can get infected by ingesting contaminated
water, such as by drinking it or by eating vegetables that were washed or
irrigated with contaminated water.

4. Epidemiology
 Fascioliasis is found in more than 50 countries, especially where sheep or
cattle are reared. Fasciola hepatica is found in all continents except
Antarctica. Fasciola gigantica has been found in some tropical areas. Except
for parts of Western Europe, human fascioliasis has mainly been
documented in developing countries.
 Fascioliasis occurs in many areas of the world and usually is caused by F.
hepatica, which is a common liver fluke of sheep and cattle. In general,
fascioliasis is more common and widespread in animals than in people. Even
so, the number of infected people in the world is thought to exceed two
million.

5.  Fasciola hepatica is found in focal areas of more than 70 countries, in all
continents except Antarctica. It is found in parts of Latin America, the
Caribbean, Europe, the Middle East, Africa, Asia, and Oceania. Fasciola
gigantica is found in fewer geographic regions. Human cases have been
reported in the tropics, in parts of Africa and Asia, and also in Hawaii.
 In some areas where fascioliasis is found, human cases are uncommon
(sporadic). In other areas, human fascioliasis is very common (hyperendemic).
For example, the areas with the highest known rates of human infection are
in the Andean highlands of Bolivia and Peru.

7.  Infective Fasciola larvae (metacercariae) are found in contaminated water—typically, stuck
to (encysted on) water plants or, potentially, floating in the water—such as in marshy
areas, ponds, or flooded pastures. The main way people (and animals) become infected is
by eating raw watercress or other contaminated water plants (for example, if the plants are
eaten as a snack or in salads or sandwiches). Some data suggest people also might get
infected by ingesting contaminated water, such as by drinking it or by eating vegetables
that were washed or irrigated with contaminated water. Under unusual circumstances,
infection might result from eating raw or undercooked sheep or goat liver that contains
immature forms of the parasite.
 The possibility of becoming infected in the United States should be considered, despite the
fact that few locally acquired cases have been documented. The prerequisites for
the Fasciola life cycle exist in some parts of the United States. In addition, transmission
because of imported contaminated produce could occur, as has been documented in
Europe

8. Causal Agent
 The trematodes Fasciola hepatica (also known as the common liver fluke or the
sheep liver fluke) and Fasciola gigantica are large liver flukes (F. hepatica: up to
30 mm by 15 mm; F. gigantica: up to 75 mm by 15 mm), which are primarily
found in domestic and wild ruminants (their main definitive hosts) but also are
causal agents of fascioliasis in humans.
 Although F. hepatica and F. gigantica are distinct species, “intermediate forms”
that are thought to represent hybrids of the two species have been found in
parts of Asia and Africa where both species are endemic. These forms usually
have intermediate morphologic characteristics (e.g. overall size, proportions),
possess genetic elements from both species, exhibit unusual ploidy levels (often
triploid), and do not produce sperm. Further research into the nature and origin
of these forms is ongoing.

9.  Left: Fasciola hepatica egg in an unstained wet mount (400x magnification).
 F. Hepatica eggs are broadly ellipsoidal, operculated, and measure 130–150 μm by 60–90 µm.
 Right: Adult Fasciola hepatica fluke stained with carmine (30mm x 13mm).

10. Life Cycle
 1.Immature eggs are discharged in the biliary ducts and passed in the stool .
 2.Eggs become embryonated in freshwater over ~2 weeks ;
 3.embryonated eggs release miracidia ,
 4.which invade a suitable snail intermediate host .
 In the snail, the parasites undergo several developmental stages (4a sporocysts , 4b
rediae , and 4c cercariae ).
 5.The cercariae are released from the snail and
 6.encyst as metacercariae on aquatic vegetation or other substrates. Humans and other
mammals become infected by ingesting metacercariae-contaminated vegetation (e.g.,
watercress) .
 7.After ingestion, the metacercariae excyst in the duodenum and
 8.penetrate through the intestinal wall into the peritoneal cavity. The immature flukes then
migrate through the liver parenchyma into biliary ducts, where they mature into adult
flukes and produce eggs .
 In humans, maturation from metacercariae into adult flukes usually takes about 3–4
months; development of F. gigantica may take somewhat longer than F. hepatica.

12. Classification
 The Acute Phase (Acute Fascioliasis)
 In the early (acute) phase, symptoms can occur as a result of the parasite’s migration from the
intestines to and through the liver. Symptoms can include gastrointestinal problems such as nausea,
vomiting, and abdominal pain/tenderness. Fever, rash, and difficulty breathing may occur.
 The acute phase is also referred to as the migratory, invasive, hepatic, parenchymal, or larval phase.
Immature larval flukes migrate through the intestinal wall, the peritoneal cavity, the liver capsule, and
hepatic tissue and, ultimately, to the bile ducts. The acute phase lasts up to approximately 3 to 4
months and ends when the larvae reach and mature in the bile ducts. Larval migration, especially
through the liver, can result in tissue destruction, inflammation, local or systemic toxic/allergic
reactions, and internal bleeding. Symptoms, in addition to those listed above, can include urticaria,
cough, and shortness of breath. This phase can be life threatening in sheep infected with large inocula
of parasites. However, severe illness is uncommon in people, although some young children have
intense abdominal pain.

13.  The Chronic Phase (Chronic Fascioliasis)
 The chronic phase is also referred to as the biliary or adult phase. The chronic phase
begins when immature larvae reach the bile ducts, mature into adult flukes, and start
producing eggs. The eggs are passed from the bile ducts into the intestines and then
into the feces. During this phase, the patient may be asymptomatic for months, years,
or indefinitely. The only finding on routine blood testing might be peripheral
eosinophilia, which typically is less prominent than during the acute phase.
 During the chronic phase (after the parasite settles in the bile ducts), the clinical
manifestations may be similar or more discrete, reflecting inflammation and blockage of
bile ducts, which can be intermittent. Inflammation of the gallbladder and pancreas also
can occur.

14. Diagnosis
 The standard way to be sure a person is infected with Fasciola is by seeing the parasite. This is
usually done by finding Fasciola eggs in stool (fecal) specimens examined under a
microscope. More than one specimen may need to be examined to find the parasite.
Sometimes eggs are found by examining duodenal contents or bile.
 Infected people don’t start passing eggs until they have been infected for several months;
people don’t pass eggs during the acute phase of the infection. Therefore, early on, the
infection has to be diagnosed in other ways than by examining stool. Even during the chronic
phase of infection, it can be difficult to find eggs in stool specimens from people who have
light infections.
 Certain types of blood tests can be helpful for diagnosing Fasciola infection, including routine
blood work and tests that detect antibodies (an immune response) to the parasite

15.  The drug of choice is triclabendazole. The drug is given by mouth,
usually in two doses. Most people respond well to the treatment.
 Triclabendazole 10mg/kg 1-2 days.
 Nitazoxanide might be effective therapy in some patients. The drug
is given orally, with food. The dosage regimen for adults is 500 mg
po bid (twice a day) for 7 days.
 Bithionol 30-50mg/kg on alternate days ,10-15 days.
 Prednisolone 10-20mg/day to tackle toxaemia.
Treatment

16. Prevention & Control
 No vaccine is available to protect people against Fasciola infection.
 In some areas of the world where fascioliasis is found (endemic), special control
programs are in place or are planned. The types of control measures depend on the
setting (such as epidemiologic, ecologic, and cultural factors). Strict control of the
growth and sale of watercress and other edible water plants is important.
 Individual people can protect themselves by not eating raw watercress and other water
plants, especially from Fasciola-endemic grazing areas. As always, travelers to areas
with poor sanitation should avoid food and water that might be contaminated (tainted).
Vegetables grown in fields that might have been irrigated with polluted water should be
thoroughly cooked, as should viscera from potentially infected animals.

17. THANK YOU !