1A: General Characteristics of Trematodes

Multicellular

The cellular classification of trematodes.

Eukaryotes

The membrane-bound classification of trematodes.

Parasites

The lifestyle of trematodes.

Unsegmented

The segmentation of trematodes.

No coelom, Tough syncytial tegument on surface, & anterior & ventral suckers

3 physical characteristics of trematodes.

Monoecious

The separation of reproductive parts of trematodes.

Schistosomes

The classification of helminths that are dioecious.

Protection against digestive enzymes present in the gut of the host

The significance or importance of tough syncytial teguments being found on the surface of trematodes.

Oral Sucker

The anterior sucker of trematodes.

Complex & Digenetic

The life cycle of trematodes.

Digenetic (2)

The number of host organisms required for trematodes to have a complete life cycle and the term for it.

Snails

The intermediate host of trematodes.

Infected host releases egg containing miracidium ⟶ Snail ingests miracidium ⟶ Sporocyst ⟶ Radial Stage ⟶ Transform to cercaria ⟶ Exit snail ⟶ Cercaria ingested by fish ⟶ Metacercaria ⟶ Consumed by humans or mammals ⟶ Develop into adults

The 10 steps in the life cycle of trematodes.

Sporocyst

The stage of development trematodes turn into after miracidium. A sausage-like structure.

Radial Stage

The stage of development trematodes turn into after sporocyst.

Cercaria

The stage of development trematodes turn into after radial stage.

Metacercaria

The stage of development trematodes turn into after cercaria. The infective stage of fishborne parasites.

2 weeks

The development time for radial stage trematodes to transform into cercaria.

Parasitologic, Serologic, & Microscopy

3 means of diagnosis of trematode infection.

Parasitologic

The means of diagnosing trematode infections through detecting parasite eggs.

Serologic

The means of diagnosing trematode infections through antibody detection.

Kato-Katz Technique

The gold standard technique of detecting parasitic eggs.

Labor intensive, Requires microscopic skills, & Low sensitivity

3 limitations of the Kato-Katz technique.

Requires thousands of 40mg stool samples and replicates

The reason that the Kato-Katz technique is labor intensive.

Underestimates infections in those who are lightly infected

The reason that the Kato-Katz technique is prone to low sensitivity.

Difficult in large scale production, Low sensitivity & specificity, & Cross reaction with other antigens of the parasites

3 limitations of antibody detection in serologic means of diagnosis.

Recombinant agents

What improves the limitation of cross-reactions of other pathogen antigens in antibody detection.

Soluble Egg Antigen (SEA)

A requirement of antibody detection that is used to prepare reagents.

Mice are abdominally exposed ⟶ Eggs are laid in liver ⟶ Livers are removed & homogenized ⟶ Liquid is centrifuged

The 4 steps of isolating the Soluble Egg Antigen in antibody detection of trematode infections.

Isolate the whole, intact eggs

Why mice liver are removed and homogenized in the antibody detection of trematode infections.

Circumoval Precipitin Test (COPT) & Enzyme-Linked Immunosorbent Assay (ELISA)

2 tests done during the antibody detection of trematode infections after the isolation of the Soluble Egg Antigen (SEA).

Circumoval Precipitin Test (COPT)

An antibody detection test that uses intact eggs for Soluble Egg Antigen centrifuging.

Enzyme-Linked Immunosorbent Assay (ELISA)

An antibody detection test that uses crushed eggs for Soluble Egg Antigen centrifuging.

Collect patient blood & centrifuge ⟶ Serum + drop of blood on slide & whole eggs for SEA ⟶ 24 hour incubation for egg antigen diffusion ⟶ microscope examination

The 4 steps in the process of the Circumoval Precipitin Test (COPT).

Visible precipitates around the egg cell

The positive test results during a Circumoval Precipitin Test (COPT).

96 well ELISA plate & different recombinant antigens ⟶ Mix antigens in equivalent molar concentrations

The 2 steps in the process of the Enzyme-Linked Immunosorbent Assay (ELISA).

Cannot discriminate previous & current infections & must be coupled with stool PCR or microscopy

2 limitations of the Enzyme-Linked Immunosorbent Assay (ELISA).

Antibodies remain in the blood 5 years after parasite death

Why the Enzyme-Linked Immunosorbent Assay (ELISA) has a limitation of causing false positives if someone had a previous infection.

Praziquantel cannot kill juveniles & No vaccine is developed against worms

2 weakpoints in the disease control of trematode infections.

Repeated large-scale use led to resistant S. mansoni strains.

The reason why praziquantel cannot kill juveniles.

Formalin Ether Concentration Technique

The test used in the microscopy-centered diagnosis of trematode infections.

10% formalin & ether

The 2 reagents used in the Formalin Ether Concentration Technique.

Fixative

The purpose of formalin in the Formalin Ether Concentration Technique.

Dissolves fats in stool

The purpose of ether in the Formalin Ether Concentration Technique.

Parasite eggs have a high specific gravity

The reason why parasite eggs are recovered in the sediment rather than displaying sedimentation floatation.

S. japonicum

S. haematobium

S. mansoni

70-100 um

The length of S. japonicum spines.

114-180 um

The length of S. haematobium & S. mansoni spines.

Vestigial spine

The type of spines seen in S. japonicum.

Terminal spine

The type of spines seen in S. haematobium.

Lateral spine

The type of spines seen in S. mansoni.