24 Questions
What is the common name of the Fasciolopsis buski?
Intestinal Fluke
Which of the following is a characteristic feature of Heterophyes heterophyes?
Presence of a genital sucker
What is the common habitat of Echinostoma ilocanum?
Intestine
What is the name of the pancreatic fluke?
Eurytrema pancreaticum
What is the common name of the Paragonimus westermani?
Lung Fluke
Which of the following is NOT a characteristic feature of trematodes?
Round body
How are Fasciola spp. typically transmitted to humans?
Through ingestion of undercooked or raw aquatic plants
What is the name of the smallest trematode?
Heterophyes heterophyes
What is the definitive host of Paragonimus westermani?
Humans
What is the characteristic feature of Paragonimus westermani eggs?
Abopercular thickening
What is the habitat of Schistosoma spp.?
Mesenteric veins or blood
What is the mode of transmission of Paragonimus westermani?
Ingestion of undercooked crabs with metacercaria
What is the intermediate host of Paragonimus westermani?
Crabs
What is the diagnosis of Paragonimus westermani infection?
Microscopy of stool or sputum
What is the characteristic feature of Schistosoma japonicum eggs?
Oval with recurved hook or knob
What is the habitat of Schistosoma japonicum?
Superior mesenteric vein
What is the habitat of Fasciolopsis buski?
Small intestine
What is the mode of transmission for Echinostoma ilocanum?
Ingestion of metacercariae encysted in snails
What is the characteristic feature of the adult worm of Heterophyes heterophyes?
Gonotyl
What is the intermediate host of Eurytrema pancreaticum?
Macrochlamys indica
What is the habitat of Paragonimus westermani?
Lungs
What is the characteristic feature of the eggs of Fasciolopsis buski?
Large and operculated
What is the disease caused by Echinostoma ilocanum?
All of the above
What is the mode of transmission for Heterophyes heterophyes?
Ingestion of metacercariae encysted in fish
Study Notes
Intestinal Flukes
- Fasciolopsis buski:
- Also known as the Giant Intestinal Fluke
- 1st Intermediate Host (IH): Segmentiina
- 2nd IH: Water plants
- Mode of Transmission (MoT): Ingestion of encysted metacercaria from aquatic plants
- Adult worms:
- No cephalic cone
- Intestinal ceca is simple and unbranched
- Dendritic testes arranged in tandem
- Branched ovary lies to the right of the midline
- Eggs:
- Large and operculated
- Indistinguishable from Fasciola
- Disease:
- Parasite attached to the small intestine (Pathology due to adult)
- Traumatic, obstructive, toxic, and marked eosinophilia and malabsorption of vitamins
- Diagnosis:
- Direct Fecal Smear (DFS), Kato Katz
- Clinical impression
- Echinostoma ilocanum:
- Also known as Garrison's fluke
- First Intermediate Host (IH): Gyraulus convexiusculus
- 2nd IH: Pila luzonica and Vivipara angularis
- Mode of Transmission (MoT): Ingestion of metacercariae encysted in snails
- Adult worms:
- Circumoral disk (spines surrounding the oral sucker)
- Testes deeply bilobed in tandem
- Intestinal ceca simple and unbranched
- Eggs:
- Straw-colored or light brown, operculated
- Less prominent operculum (dot-like appearance)
- Disease:
- Inflammation at the site of attachment
- Diarrhea (in heavy infections)
- Intoxication due to release of metabolites
- Heterophyes heterophyes:
- Wide range of Intermediate Hosts (FISH)
- Mode of Transmission (MoT): Ingestion of encysted metacercariae in fish
- Habitat: Small intestine
- Adult worm:
- Gonotyl – characteristic for Heterophyes
- Eggs:
- Light brown color, ovoid, operculated
- Embryonated
- Disease:
- Local inflammation at the site of attachment
- Diagnosis:
- Demonstration of egg from stool
- Adults may be seen during autopsy
Pancreatic Flukes
- Eurytrema pancreaticum:
- Also known as the Pancreatic Fluke
- Humans act as accidental host
- 1st Intermediate Host (IH): Macrochlamys indica
- 2nd IH: Technomyrmex deterquens
- Mode of Transmission (MoT): Ingestion of ant or grasshopper
Lung Flukes
- Paragonimus westermani:
- Also known as the Oriental Lung Fluke
- Found in the sputum or feces and embryonate in water
- 1st Intermediate Host (IH): Antemelania asperata
- 2nd IH: Sundathelphusa philippina (freshwater/mountain crab)
- Mode of Transmission (MoT): Ingestion of undercooked crabs with metacercaria
- Reservoir Hosts: Dogs, Cats, Rodents
- Paratenic Hosts: Boars and Pigs
- Adult:
- Reddish-brown, coffee bean-shaped
- Presence of spines on tegument
- Testes: Lobed, usually two, arranged in opposites
- Ovary: Anterior to testes and posterior to ventral sucker
- Eggs:
- Opercular shoulder
- Abopercular thickening (characteristic of Paragonimus)
- Disease:
- Lung fluke disease
- Heavy infections would have dry cough, blood-stained or rust-colored sputum (fishy odor)
- Mimics signs of TB
- Pathology: Adult worms provoke a granulomatous reaction
- Diagnosis:
- Microscopy: Detection of eggs in stool or sputum
Blood Flukes
- Schistosoma spp.:
- MoT: Skin penetration
- Infective Stage (IS): Fork-tailed cercaria
- Intermediate Host (IH): Snails
- Habitat: Mesenteric veins or blood
- Worms ingest RBCs and possess hemoglobinase breaking down globulin and hemoglobin
- Main pathology is caused by the egg
- Types of Schistosoma:
- S. japonicum: Oriental blood fluke
- S. mansoni: Manson's blood fluke
- S. haematobium: Vesical blood fluke
Generalities
- All trematodes appear flat and leaf-like, except schistosomes
- All possess two suckers, except Heterophyes heterophyes
- Eggs (diagnostic): Operculated except Schistosoma (non-operculated)
- Mode of Transmission (MoT): Ingestion (except Schistosoma)
- Mature Eggs: COSH
- Smallest Trematode: Heterophyes heterophyes
- Biggest Trematode: Fasciolopsis buski
- Life Cycle: Egg → Miracidium → Sporocyst → Redia → Cercaria → Metacercaria → Adult Worm
Test your knowledge of intestinal flukes and liver flukes, including their habitats, intermediate hosts, and definitive hosts. Learn about Fasciolopsis buski, Echinostoma ilocanum, and more.
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