28 Questions
Which type of eggs is associated with Paragonimus and Fasciolopsis?
Immature eggs
In terms of habitat, where do Schistosomes reside?
Mesenteric vein
What is the mode of transmission for Schistosomes?
Skin penetration
Which of the following is an infective stage for most Trematodes except Schistosomes?
Metacercaria
What is the morphology of Trematodes, excluding Schistosomes?
Flat and leaf-like
Which of the following is not a general feature of Trematodes?
Having separate sexes
Which species of fluke inhabits the portal blood stream of vertebrates?
Schistosoma japonicum
What is the class of the phylum Platyhelminthes that includes flukes?
Trematoda
Which of the following flukes inhabits the lungs of vertebrates?
Paragonimus westermani
What is the name of the species of fluke that inhabits the small intestines of vertebrates?
Fasciolopsis buski
Which of the following is NOT a species of liver fluke?
Echinostoma ilocanum
What is the drug of choice for the treatment of lung flukes?
Praziquantel
Which drug can be used as an additional treatment for lung fluke infection involving cerebral symptoms?
Corticosteroids
Which drug is considered an alternative to praziquantel for lung fluke treatment?
Bithionol
What is the mechanism of action of triclabendazole in affecting lung flukes?
Damaging the nuclear membrane of the parasite
In the diagnosis of paragonimiasis, which diagnostic tool is considered the most basic and readily available?
Acid fast stain
How does human infection with P. westermani occur?
By eating undercooked or pickled crab or crayfish
Where do the miracidia hatch and seek the first intermediate host?
A snail
What is the infective stage for the mammalian host in the life cycle of P. westermani?
Metacercariae
How does P. westermani enter the human lungs during the infection process?
Through the intestinal wall
Where does the parasite encyst as a metacercaria in the crustacean host?
Gills
What prevents the completion of the life cycle of P. westermani when the worms reach the brain or striated muscles?
Eggs getting trapped in these structures
What is the size of the Adult Heterophyid Fluke?
2 mm in length
Where is the genital sucker located in the Adult Heterophyid Fluke?
At the left posterior border of the ventral sucker
Which suckers does the Adult Heterophyid Fluke possess?
Oral, Genital, Acetabulum
Where are the vitellaria located in the Adult Heterophyid Fluke?
At the lateral sides, occupying the lower thirds of the body
Which method is used for stool analysis to detect the presence of eggs?
Kato-Katz method
Why is PCR considered a useful diagnostic tool for low-intensity heterophyid infections?
Because it has higher sensitivity, particularly for low-intensity infections
Study Notes
Diagnosis of Heterophyid Fluke
- Clinical history: Peptic Ulcer Disease manifestation with bowel disturbance and history of eating raw fish
- Adult Heterophyid Fluke: elongated, oval, or pyriform, measuring 2 mm in length
- Tegument: fine scale-like spines
- Genital sucker: located at the left posterior border of the ventral sucker, also known as gonotyl
- Three suckers: oral sucker, genital sucker, and acetabulum (ventral sucker at the posterior border)
- Esophagus: present
- Ovary: one, globular, and slightly lobed, located in the submedian, pre- or post-testicular area
- Testes: two, variously arranged, located in the posterior end of the body
- Hermaphrodite: yes
- Vitellaria: located at the lateral sides, occupying the lower thirds of the body
Detection and Diagnosis of Heterophyid Fluke
- Kato-Katz method (Stool analysis): detects the presence of eggs
- Definitive diagnosis: has higher sensitivity compared to formalin-ether/ethyl acetate concentration technique
- Difficult to distinguish between Clonorchis and Opistorchis eggs
- Heterophyid eggs: referred to as Opisthorchid-like eggs where the liver fluke is endemic
- PCR: may be useful as a sensitive diagnostic tool, particularly for low-intensity heterophyid infections
Trematodes (Flukes)
- Phylum: Platyhelminthes
- Class: Trematoda
- Infection: 4 types
- Blood Flukes: Schistosomes
- Liver Flukes: Fasciola, Clonorchis, Opistorchis
- Lung Flukes: Paragonimus worms
- Intestinal Flukes: Fasciolopsis, Echinostoma, Heterophyids
Characteristics of Trematodes (except Schistosomes)
- Flat, leaf-like body
- Hermaphrodite
- Egg: Operculated
- Habitat: Lungs, Liver, bile passage, intestine
- Mode of transmission (MOT): Ingestion
- Infective stage: Metacercaria
- Two intermediate hosts: Snail and Fish, Crab, Snail, or Plant/Vegetation
Characteristics of Schistosomes (Blood Flukes)
- Elongated and Cylindrical body
- Separate sexes
- Egg: Non-operculated
- Habitat: Mesenteric vein
- Mode of transmission (MOT): Skin penetration
- Infective stage: Cercaria
- Intermediate host: Snail (only one)
Intestinal Flukes
- Species: Heterophyid Flukes, Echinostomid Flukes, Fasciolid Fluke
- Second Intermediate Hosts:
- Snail: Echinostoma ilocanum, Artyfechinostoma malayanum
- Water plant: Fasciola hepatica, Fasciola gigantica, Fasciolopsis buski
- Freshwater fish: Clonorchis sinensis, Opistorchis felinus, Heterophyes
- Crab: Paragonimus westermani
Treatment Strategies
- Praziquantel: Drug of choice, 25 mg/kg of BW x 3 times a day, for 2-3 days
- Corticosteroids: used as an additional drug for cerebral involvement
- Bithionol: alternative drug, 15-25 mg/kg BID on alternate days for 10-15 days
- Triclabendazole: damages the nuclear membrane of the parasite
Test your knowledge on intestinal and lung flukes with this quiz covering topics like Paragonimus westermani, Heterophyid Flukes, Echinostomid Flukes, and Fasciolid Fluke. Learn about Trematodes infection and the different types of flukes that can affect humans.
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