CDC Fascioliasis

The trematodes Fasciola hepatica (also known as the ____or the __)

common liver fluke,sheep liver fluke

Fasciola gigantica are large liver flukes (F. hepatica: up to __

30 mm by 15 mm

F. gigantica up to ____

75 mm by 15 mm

Fasciola primarily found in__ (their main definitive hosts) but also are causal agents of fascioliasis in humans.

domestic and wild ruminants

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 _ where both species are endemic.

Asia and Africa

Immature eggs are discharged in the __ and passed in the stool

biliary ducts

1 Eggs become embryonated in freshwater over ~_____, which invade a suitable snail intermediate host

2 weeks

2 embryonated eggs release_____________

miracidia

3 which invade a suitable snail ____________

intermediate host

(4) In the snail, unundergo several developmental stages (sporocysts, rediae , and cercariae . The cercariae are released from the snail (5) and encyst as__ on aquatic vegetation or other substrates.

metacercariae

(5) Humans and other mammals become infected by ingesting __ (e.g., watercress) duodenum

metacercariae-contaminated vegetation

(6) After ingestion, the metacercariae excyst in the_______

duodenum

7 and penetrate through the intestinal wall into the ______________.

peritoneal cavity

7 The immature flukes then migrate through the liver parenchyma into ___, where they mature into adult flukes and produce eggs

biliary ducts

8 In humans, maturation from metacercariae into adult flukes usually takes about development of F. gigantica may take somewhat longer than F. hepatica

3–4 months

At least _ species have been identified as intermediate hosts for one or more Fasciola spp

20 snai

Fasciola hepatica is found on all inhabited continents, in more than __ countries, particularly where _ are raised. 70, sheep or cattle

“Intermediate forms” have been reported from areas, particularly in Asia, where both ___ are endemic.

F. hepatica and F. gigantica

However, other ________with unusual ploidy and morphology occasionally have been reported in areas where the two species are not sympatric (e.g., the United Kingdom), which underscores the need for more research into atypical forms

non-sperm-producing forms

Eggs of Fasciola spp. are broadly ellipsoidal, are operculated, measure 130–150 µm long by______wide, and are passed unembryonated in feces.

60–90 µm

During the early phase of the infection (usually referred to as the acute phase also, the migratory, invasive, hepatic, parenchymal, or larval phase), the period when the larval fluke is migrating from the intestines and through the liver parenchyma, larval migration can be associated with __.

inflammation, tissue destruction, and toxic/allergic reactions

Nonspecific symptoms/signs
(e.g., a_) and laboratory abnormalities (e.g., peripheral
eosinophilia, elevated transaminase levels) may develop.

bdominal pain, nausea, vomiting, hepatomegaly, malaise, fever, cough

Adult of F. hepatica stained with carmine