Parasite Transmission and Hosts Quiz

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Questions and Answers

What is the disadvantage of using the Zinc sulfate flotation technique for parasite recovery?

It yields a preparation with more fecal debris (correct)

It is difficult to perform

It requires a lot of time

It stains the sample excessively

What is the main principle of the Zinc sulfate flotation technique?

Based on sample texture

Based on differences in specific gravity (correct)

Based on sample color

Based on sample volume

Why is the Zinc sulfate flotation technique able to yield a cleaner preparation compared to other methods?

It does not require stains

It requires less sample

It can remove more fecal debris (correct)

It uses a special microscope

Which layer of the test tube do parasites typically float to in the Zinc sulfate flotation technique?

Upper layer Signup and view all the answers

What is the final step in the microscopic examination after using the Zinc sulfate flotation technique?

Staining Signup and view all the answers

Which type of immunopathologic reaction involves antibody-antigen complex deposition in organs and tissues?

Type 3 Signup and view all the answers

In the context of allergic reactions to parasites, which example manifests as pruritus ani?

Enterobius vermicularis Signup and view all the answers

What mechanism characterizes Type 2 immunopathologic reactions?

Antibody + parasite antigen on cell surface Signup and view all the answers

Which parasitic infection may lead to the development of cancer of the biliary ducts?

Clonorchis sinensis Signup and view all the answers

What is the outcome of Type 1 immunopathologic reactions involving parasite antigen and IgE?

Bronchospasm Signup and view all the answers

Which infection triggers sensitized T cell reactions with antigens according to the text?

Toxoplasma gondii Signup and view all the answers

What is a common feature of Nematodes?

Separate sexes with possible attachment teeth Signup and view all the answers

What is a key characteristic of the larvae of Nematodes?

Aerobic Signup and view all the answers

What is recommended regarding the collection of stool specimens?

Collect stool in a clean, water-tight container Signup and view all the answers

What is the recommended amount of stool to collect for testing?

2-5g Signup and view all the answers

What is the preferred method of sealant for the container of stool specimens?

Ziplock plastic bag Signup and view all the answers

What is a vital consideration in specimen collection for parasites?

Properly sealed to prevent contamination Signup and view all the answers

What specimen is the specimen of choice for detecting the blood fluke Schistosoma haematobium?

Genitourinary secretions Signup and view all the answers

In cases of suspected malaria infection, what type of blood smears must be prepared and examined within 1 hour of collection?

Thick and thin blood smears Signup and view all the answers

Which specimen may be utilized to detect the presence of Toxoplasma gondii in tissues?

Tissue and biopsy specimens Signup and view all the answers

What is the specimen of choice in patients with suspected amebic liver abscess?

Abscess material from the liver Signup and view all the answers

If detection of parasite motility is desired, what must be immediately examined?

Wet preparations Signup and view all the answers

Which material is used to detect eggs of the tapeworm Taenia spp?

Feces Signup and view all the answers

How do blood-sucking insects contribute to the transmission of diseases?

By transporting the infective stage of parasites Signup and view all the answers

Which mechanism is NOT a way in which parasites may damage their hosts?

Metastasis to distant organs Signup and view all the answers

Which parasite is transmitted through the inhalation of eggs?

Enterobius vermicularis Signup and view all the answers

What is a common way for fecal-oral transmission of parasites to occur?

Consuming contaminated food and water Signup and view all the answers

Which mechanism may involve systemic increase in circulating eosinophils?

Stimulation of host tissue reaction Signup and view all the answers

Which portal of exit is associated with the eggs of medically important roundworms?

Anus Signup and view all the answers

How do migrating birds contribute to human infections?

By acting as reservoir hosts for parasites like Capillaria philippinensis Signup and view all the answers

What is a way in which parasites may open pathways for other pathogens into the tissues?

Trauma or physical damage Signup and view all the answers

Which mode of transmission involves the bite of a blood-sucking insect vector?

Inhalation of eggs Signup and view all the answers

What role do paratenic hosts play in the lifecycle of parasites?

They act as transport for the infective stage of parasites Signup and view all the answers

Study Notes

Parasite Transmission and Exposure

Migratory birds serve as reservoir hosts for the parasite Capillaria philippinensis, which is typically acquired through contaminated freshwater.
Paratenic hosts act as transport vehicles for parasites, allowing them to reach their final hosts.

Sources of Exposure

Contaminated soil and water can harbor parasitic worms or helminths, such as Ascaris lumbricoides, Trichuris trichiura, and Strongyloides stercoralis.
Blood-sucking insects, like female Anopheles mosquitoes, can transmit parasites like Plasmodium.
Domestic or wild animals can harbor parasites, such as the dog tapeworm Echinococcus granulosus.
Another person's clothing, bedding, or environment can also serve as a source of exposure to parasites.

Modes of Transmission

Fecal-oral transmission: the most common mode of transmission for most intestinal parasites, typically through contaminated food and water.
Contaminated water: can transmit intestinal protozoa and the embryonated egg stage of intestinal roundworms.
Penetration of the skin: can occur through contact with contaminated soil or water, allowing parasites like hookworms and Strongyloides to enter the body.
Bite of blood-sucking insects: can transmit parasites like malaria, leishmaniasis, and trypanosomiasis.
Inhalation: can transmit parasites like pinworms or Enterobius vermicularis.
Transplacental or congenital infection: can occur through transmission from mother to child, such as with Toxoplasma gondii.
Transmammary infection: can occur through mother's milk, such as with Strongyloides.
Sexual intercourse: can transmit parasites like Trichomonas vaginalis.

Portals of Exit

Anus: the most common portal of exit for parasite eggs, such as those of medically important roundworms.
Urine: can transmit parasites like Trichomonas vaginalis, Strongyloides stercoralis, and Schistosoma haematobium.
Sputum: can transmit parasites like lung fluke Paragonimus westermani and the intestinal roundworm Ascaris lumbricoides.
Vaginal discharge: can transmit parasites like Trichomonas vaginalis.

Mechanisms of Disease Production

Trauma or physical damage: can occur through direct physical damage caused by the parasite.
Lytic necrosis: can occur through enzymes and other substances released by parasites, such as Entamoeba histolytica.
Stimulation of host tissue reaction: can occur through cellular proliferation and infiltration at the site of parasite entry.
Toxic and allergic phenomena: can occur through immunopathologic reactions, such as anaphylactic shock, bronchospasm, and local inflammation.

Specimen Collection and Handling

Stool specimens: should be collected in a clean, water-tight container, and covered tightly, with approximately 2-5g of stool recommended.
Blood specimens: should be collected using universal precautions and asepsis, with blood from the fingertip or earlobe (without anticoagulant) or from standard venipuncture (with anticoagulant).
Cerebrospinal fluid (CSF) specimens: should be immediately examined if detection of parasite motility is desired.
Tissue and biopsy specimens: can be used to detect parasites like Leishmania, Toxoplasma gondii, Trypanosoma, and Trichinella spiralis.
Genitourinary secretions: can be used to detect parasites like Schistosoma haematobium.

Microscopic Examination

Three stages: including preparation, concentration, and staining.
Zinc sulfate flotation technique: uses differences in specific gravity to separate parasites from debris, with advantages including removal of fecal debris and yielding a cleaner preparation.
Permanent stains: used in the final step of microscopic examination, involving staining of a fixed sample on a slide glass.

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Description

Test your knowledge on parasitic transmission and hosts with this quiz. Learn about how migratory birds serve as reservoir hosts for parasites and the role of paratenic hosts in parasite transmission. Explore sources of exposure to infection or infestation from contaminated soil or water.