Trematodes
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Questions and Answers

What is the characteristic feature of the body of trematodes?

  • Presence of a tail
  • Segmented body
  • Presence of anus
  • Presence of two suckers (correct)

    • Which type of fluke is responsible for water-borne parasitic disease?

  • Lung fluke
  • Hepatic fluke
  • Blood fluke (correct)
  • Intestinal fluke

    • Where do adult worms of S.mansoni inhabit in the human body?

  • Mesenteric veins of sigmoido-rectal region (correct)
  • Mesenteric veins of ileo-cecal region
  • Hepatic veins
  • Veins of vesical and pelvic plexuses

    • What is the intermediate host of the schistosome life cycle?

    <p>Snail</p> Signup and view all the answers

    What is the process by which the conjoined couple of worms ascend the mesenteric vessels?

    <p>Using their suckers to move against the flow of blood</p> Signup and view all the answers

    What is the type of reproduction that occurs within the intermediate host?

    <p>Asexual reproduction</p> Signup and view all the answers

    What is the primary site where the eggs of S.haematobium are discharged?

    <p>Urine</p> Signup and view all the answers

    What is the intermediate host for S.mansoni?

    <p>Biomphalaria</p> Signup and view all the answers

    What is the primary site where the eggs of S.mansoni and S.japonicum are swept back into the circulation and lodge in?

    <p>Liver</p> Signup and view all the answers

    What is the final host for S.japonicum?

    <p>Man and domestic animals</p> Signup and view all the answers

    What is the stage of the parasite that penetrates human skin?

    <p>Cercariae</p> Signup and view all the answers

    What is the most significant pathology associated with in schistosomiasis?

    <p>The schistosome eggs</p> Signup and view all the answers

    What is the result of a granulomatous reaction surrounding the eggs in the liver with S.mansoni and S.japonicum?

    <p>Fibrosis and impeded blood flow to the liver</p> Signup and view all the answers

    What is the characteristic of S.haematobium infections?

    <p>Urinary tract involvement and bladder obstruction</p> Signup and view all the answers

    What is the term for the symptoms that occur after cercarial penetration in travelers to endemic countries?

    <p>Katayama fever</p> Signup and view all the answers

    What is the primary cause of morbidity and mortality in chronic schistosomiasis?

    <p>Immunological reaction and granuloma formation</p> Signup and view all the answers

    What is the duration of localized pruritus after cercarial penetration?

    <p>Few hours</p> Signup and view all the answers

    What is the incubation period for the development of Katayama syndrome in non-immune individuals?

    <p>1-2 months</p> Signup and view all the answers

    What is a common symptom associated with the onset of fever in this syndrome?

    <p>Right upper quadrant pain</p> Signup and view all the answers

    What is the result of gradual accumulation of scar tissue within the bladder and ureters?

    <p>Hydronephrosis and bladder calcification</p> Signup and view all the answers

    What type of inflammation is formed by host lymphocytes, eosinophils, and macrophages in response to trapped parasite eggs?

    <p>Delayed-type hypersensitivity granulomatous inflammation</p> Signup and view all the answers

    What is the result of eggs passing into the brain, spinal cord, and meninges?

    <p>Central nervous system disorders</p> Signup and view all the answers

    What is the outcome of the inflammation associated with scar formation in the bladder and ureters?

    <p>Obstruction and hydronephrosis</p> Signup and view all the answers

    What is the result of chronic systemic inflammatory illness in this syndrome?

    <p>Weight loss and persisting clinical signs</p> Signup and view all the answers

    What is the primary goal of controlling schistosomiasis infection?

    <p>Eradication of the intermediate snail hosts</p> Signup and view all the answers

    What is the mechanism of action of Praziquantel against Schistosoma species?

    <p>It damages the worm's outer tegument membrane and exposes it to the immune response</p> Signup and view all the answers

    What is the typical diagnostic method for schistosomiasis?

    <p>Detection of ova in fecal or urine smear preparations</p> Signup and view all the answers

    What is the recommended treatment for Katayama syndrome?

    <p>No specific therapy is available</p> Signup and view all the answers

    What is the consequence of schistosomiasis infection if left untreated?

    <p>All of the above</p> Signup and view all the answers

    What is the effective way to prevent schistosomiasis infection?

    <p>Avoidance of swimming in contaminated water</p> Signup and view all the answers

    What is the possible outcome of inflammation caused by Schistosoma infection?

    <p>Seizures, spinal cord compression, or hydrocephalus</p> Signup and view all the answers

    What is the primary mechanism of action of Praziquantel against Schistosoma species?

    <p>It damages the worm's outer tegument membrane and exposes it to the immune response</p> Signup and view all the answers

    What is the most effective way to control Schistosoma infection?

    <p>Eradicating the intermediate snail hosts</p> Signup and view all the answers

    What is the primary purpose of biopsies in diagnosing Schistosoma infection?

    <p>To visualize the eggs in the stool or urine samples when testing is negative</p> Signup and view all the answers

    What is the role of antihistamines and corticosteroids in treating Katayama syndrome?

    <p>They may be helpful in relieving symptoms</p> Signup and view all the answers

    What is the result of the granulomatous reaction surrounding the eggs in the liver?

    <p>Fibrosis</p> Signup and view all the answers

    What is the primary method of diagnosing Schistosoma infection?

    <p>Detection of ova in fecal or urine smear preparations</p> Signup and view all the answers

    What is the consequence of chronic Schistosoma infection?

    <p>Chronic systemic inflammatory illness</p> Signup and view all the answers

    What is the primary goal of controlling Schistosoma infection?

    <p>To prevent the transmission of the disease</p> Signup and view all the answers

    What is the effect of Praziquantel on the Schistosoma worms?

    <p>It damages the worm's outer tegument membrane and exposes it to the immune response</p> Signup and view all the answers

    Study Notes

    Trematodes (Flukes)

    • Leaf-like, unsegmented flat worms with two suckers (oral and ventral)
    • Body consists of a mouth surrounded by oral suckers, a pharynx, and an esophagus; anus is absent

    Classification

    • Blood fluke
    • Intestinal fluke
    • Hepatic fluke
    • Lung fluke
    • Blood flukes: Schistosoma japonicum, Schistosoma mansoni, and Schistosoma haematobium cause water-borne parasitic disease (Schistosomiasis or Bilharziasis)

    Life Cycle

    • Adult dioecious (male and female) sexual stage within the definitive host (human)
    • Asexual reproductive stage within an intermediate host (snail)
    • Female schistosomes lay hundreds or thousands of eggs per day within the venous system
    • Eggs are discharged in urine (S. haematobium) or feces (S. mansoni and S. japonicum)
    • In water, eggs hatch, releasing miracidia (first larval stage)
    • Miracidia are eaten by certain snails (intermediate hosts)
    • Miracidia develop to a second larval stage (sporocyst stage) and then the infectious stage cercariae
    • Cercariae leave the snail and swim to penetrate human skin
    • Cercariae transform into schistosomules, which enter the peripheral circulation and eventually become adults in the hepatoportal system or venous plexus surrounding the bladder

    Pathology and Pathogenesis

    • Most significant pathology is associated with schistosome eggs, not adult worms
    • Eggs cause granulomatous reaction, leading to fibrosis in the liver with S. mansoni and S. japonicum
    • Chronic cases lead to portal hypertension, accumulation of ascites in the abdominal cavity, hepatosplenomegaly, and esophageal varices
    • S. haematobium infections involve urinary tract: urethral pain, increased urinary frequency, dysuria, hematuria, and bladder obstruction leading to secondary bacterial infections

    Signs and Symptoms

    • Acute manifestations: localized pruritus, urticarial rash, fever, headache, chills, diarrhea, and eosinophilia (snail fever or Katayama fever)
    • Chronic systemic inflammatory illness: weight loss, hepatosplenomegaly, diarrhea, constipation, and dysentery-like illness with bloody bowel movements
    • Bilharzia: S. haematobium eggs trapped in host tissues, leading to delayed-type hypersensitivity granulomatous inflammation, scar formation, and obstruction, resulting in hydronephrosis, bladder calcification, and squamous cell carcinoma of the bladder

    Diagnosis

    • Detection of ova in fecal or urine smear preparations
    • Invasive procedures—biopsy material are effective in visualizing eggs when the stool or urine sample testing is negative
    • Serology: S. mansoni, S. haematobium, S. japonicum

    Treatment

    • Praziquantel is active against all Schistosoma species
    • Praziquantel’s mechanism of action: damages the worm’s outer tegument membrane, exposing the worm to the body’s immune response, leading to worm death
    • No specific therapy is available for the treatment of Katayama syndrome
    • Antihistamines and corticosteroids may be helpful

    Control of Infection

    • Eradication of the intermediate snail hosts
    • Prevention of water pollution with human excreta
    • Avoidance of swimming in contaminated water
    • Effective treatment of infected persons

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    Microbiology Trematodes PDF

    Description

    Test your knowledge on Trematodes, also known as flukes, a type of flat worm. This quiz covers their life cycle, pathology, signs and symptoms, diagnosis, treatment, and control of infection.

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