Protozoan Pathogens and Giardia Overview

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Questions and Answers

Which of the following statements accurately describes the habitat of Giardia lamblia?

  • It is primarily found in the blood and tissues.
  • It primarily resides in the alimentary tract and urogenital tract. (correct)
  • It is exclusively found in the urogenital tract.
  • It is only found in tropical and subtropical regions.

What is the primary means of locomotion for flagellates?

  • Undulating membrane
  • Flagella (correct)
  • Cilia
  • Pseudopodia

What is the most common protozoan pathogen, based on the provided text?

  • Giardia lamblia (correct)
  • Plasmodium spp.
  • Trichomonas vaginalis
  • Cryptosporidium

Which of the following is NOT a characteristic of flagella?

<p>They are primarily responsible for cell division. (A)</p> Signup and view all the answers

Based on the text, where are flagellates grouped based on their habitat?

<p>Their location in the body (D)</p> Signup and view all the answers

What is the scientific name for the organism that causes traveller's diarrhoea, according to the text?

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

Which of the following diseases can be caused by Trichomonas vaginalis?

<p>Vaginitis (D)</p> Signup and view all the answers

What is the term used to describe flagellates found in the blood and tissues?

<p>Hemoflagellates (C)</p> Signup and view all the answers

In what part of the human small intestine is Giardia lamblia primarily found?

<p>Duodenum and upper Jejunum (B)</p> Signup and view all the answers

Which of the following is NOT a characteristic of Giardia lamblia?

<p>It primarily infects only humans. (C)</p> Signup and view all the answers

What is the infective stage of Giardia lamblia?

<p>Cyst (C)</p> Signup and view all the answers

What is the main function of the adhesive sucking disk in Giardia lamblia?

<p>To attach the parasite to the intestinal mucosa. (D)</p> Signup and view all the answers

Which of the following individuals are more susceptible to Giardia infection?

<p>Individuals with a deficiency in IgA. (B)</p> Signup and view all the answers

What is the typical shape of a Giardia lamblia trophozoite?

<p>Pear-shaped (D)</p> Signup and view all the answers

How many nuclei are typically present in a mature Giardia cyst?

<p>2-4 (A)</p> Signup and view all the answers

Which of the following statements is true about the movement of Giardia lamblia trophozoites?

<p>They move in a slow, oscillating motion. (B)</p> Signup and view all the answers

What is the typical incubation period for acute Giardiasis?

<p>1-3 weeks (A)</p> Signup and view all the answers

Which of the following is NOT a factor that increases susceptibility to Giardiasis?

<p>High levels of stomach acid (C)</p> Signup and view all the answers

How do Giardia Trophozoites multiply?

<p>Binary fission (B)</p> Signup and view all the answers

What is the primary mode of transmission for Giardia lamblia?

<p>Ingestion of contaminated food or water (C)</p> Signup and view all the answers

What are the defining characteristics of encystation in G. lamblia?

<p>High pH, low cholesterol, and presence of bile salts (D)</p> Signup and view all the answers

What is the typical clinical presentation of Giardia lamblia infection?

<p>Diarrhea, bloating, flatulence, and abdominal pain (D)</p> Signup and view all the answers

Which of these are characteristics of the Giardia Trophozoite?

<p>Two nuclei (B), Flagella (C)</p> Signup and view all the answers

In which part of the digestive system does Giardia lamblia encyst?

<p>Large intestine (B)</p> Signup and view all the answers

Which of the following is a drug of choice for treating Giardiasis?

<p>Tinidazole (C)</p> Signup and view all the answers

Which of the following is NOT an effective method for preventing Giardiasis?

<p>Community Chlorination of water (B)</p> Signup and view all the answers

What is the purpose of the Entero-Test?

<p>To collect a sample of duodenal fluid for microscopic analysis (D)</p> Signup and view all the answers

What is the duration of the Entero-Test?

<p>4-6 hours (A)</p> Signup and view all the answers

What is the primary reason for performing the Entero-Test?

<p>To confirm a diagnosis of Giardiasis when no parasites have been found in the stool (A)</p> Signup and view all the answers

Which of the following medications is recommended for the treatment of Giardiasis in pregnant females?

<p>Parmomycin (D)</p> Signup and view all the answers

How long is Metronidazole typically administered for treating Giardiasis?

<p>5-7 days (C)</p> Signup and view all the answers

What is the primary reason for using Furazolidone and Nitazoxamide in children?

<p>They have fewer adverse effects in children. (B)</p> Signup and view all the answers

Which of the following is NOT a typical symptom of chronic giardiasis in children?

<p>Bloody diarrhea (B)</p> Signup and view all the answers

What is the infective dose for Giardia lamblia?

<p>10-25 cysts (D)</p> Signup and view all the answers

Which of these is a critical virulence factor for Giardia lamblia?

<p>Variant-Specific Surface Proteins (VSSP) (B)</p> Signup and view all the answers

How does Giardia lamblia affect the intestinal epithelium?

<p>It adheres to the mucosa and disrupts the epithelial cells. (B)</p> Signup and view all the answers

Which of the following is a method of diagnosing Giardiasis using immunologic testing?

<p>Enzyme-Linked Immuno Sorbent Assay (ELISA) (D)</p> Signup and view all the answers

How does Giardia lamblia cause fat malabsorption?

<p>By directly destroying the villi responsible for fat absorption. (C)</p> Signup and view all the answers

What is a characteristic feature of Giardiasis that distinguishes it from Amebiasis and bacterial dysentery?

<p>Absence of fever (B)</p> Signup and view all the answers

Which of the following groups is LEAST susceptible to Giardia infection?

<p>Adults with healthy immune systems (B)</p> Signup and view all the answers

Flashcards

Flagellates

Parasitic protozoa with whip-like flagella for movement.

Flagella

Slender, long extensions of cytoplasm aiding in locomotion.

Kinetoplast

A structure containing mitochondrial DNA that gives rise to flagella.

Intestinal flagellates

Flagellates found primarily in the alimentary tract.

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Lumen-dwelling flagellates

Flagellates located in the alimentary and urogenital tracts.

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Giardia lamblia

Protozoan pathogen causing diarrhoea, common worldwide.

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Traveller's diarrhoea

Diarrhoea caused by giardiasis from contaminated water.

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Hemoflagellates

Flagellates found in blood and tissues.

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Chronic Giardiasis

A prolonged form of giardiasis with possible malabsorption, diarrhea, and weight loss.

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Infective Dose

As few as 10–25 cysts of Giardia can cause infection in humans.

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Risk Factors

Children and elderly debilitated persons are at higher risk for giardiasis.

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Trophozoites

The active, motile form of Giardia lamblia that interacts with the intestinal epithelium.

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Variant-Specific Surface Proteins (VSSP)

Proteins that assist Giardia in evading the immune system through antigenic variation.

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Microscopic Examination

Diagnosis of giardiasis by identifying cysts and trophozoites in stool samples.

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Fecal Antigen Detection

Methods like IFA and ELISA used to identify Giardia antigens in stool.

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Molecular Method

Advanced techniques like PCR using DNA probes for Giardia diagnosis.

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Entero-test

A diagnostic test using a capsule and thread to obtain duodenal fluid.

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Giardiasis Treatment

Medications like Metronidazole and Tinidazole treat Giardiasis effectively.

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Metronidazole

An antibiotic used for treating Giardiasis with high cure rates.

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Tinidazole

A single-dose treatment for Giardiasis, more effective than Metronidazole.

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Furazolidone

Medication given to children for Giardiasis with fewer side effects.

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Nitazoxamide

Another pediatric medication for Giardiasis with fewer side effects.

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Giardiasis Prevention

Involves proper hygiene, disposal of wastewater, and boiling water.

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Asymptomatic Carriers Treatment

Treatment of asymptomatic carriers helps prevent Giardiasis spread.

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Mode of transmission

Infection occurs via ingestion of contaminated food and water.

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Excystation

Process where cysts hatch into Trophozoites in the duodenum.

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Clinical features of giardiasis

Can range from asymptomatic to acute with various symptoms.

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Asymptomatic carriers

Individuals who carry Giardia without showing symptoms.

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Acute Giardiasis

Sudden onset of symptoms after an incubation period.

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Encystation

Process of Trophozoites forming cysts for survival.

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Giardiasis

An infection caused by Giardia lamblia, leading to weight loss and absorption issues of fats and vitamins.

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Cyst form

The infective and diagnostic form of Giardia lamblia, oval-shaped with 2-4 nuclei.

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Infection sources

Giardia lamblia is commonly found in contaminated soil, food, and water from infected feces.

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IgA deficiency

A condition making individuals more susceptible to Giardia infections due to lower immunity.

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Morphology of Trophozoites

Trophozoites have 2 nuclei, 8 flagella, and a sucking disk for attachment; measures 10-20 micrometers.

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Distribution of Giardia lamblia

Giardia lamblia is distributed worldwide and causes both endemic and epidemic intestinal diseases.

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Study Notes

Giardia Lamblia Overview

  • Giardia lamblia (also known as Giardia intestinalis, Giardia duodenalis) is a protozoan parasite.
  • It's one of the earliest protozoan parasites identified and is widespread globally.
  • It is highly prevalent in areas with poor sanitation, especially tropical and subtropical regions.
  • Travelers to these areas are at risk of giardiasis, often from contaminated water.

Giardia Lamblia Habitats

  • Giardia lamblia lives in the duodenum and upper jejunum of the human small intestine.
  • This is the only protozoan parasite found in the lumen of the human small intestine.

Giardia Lamblia Morphology

  • Trophozoites (vegetative form): Pear or pyriform-shaped, with a sucking disk for attachment to the intestinal mucosa. Two large nuclei and eight flagella.
  • Cysts (infectious form): Oval or ellipsoid, surrounded by a hyaline cyst wall. Four nuclei and remnants of axonemes.

Giardia Lamblia Transmission

  • Infection occurs by ingesting mature cysts in contaminated food or water.
  • Rare direct person-to-person transmission may occur in children or specific at-risk populations.
  • Risk factors include impaired immune systems, blood type A, and certain medical conditions.

Giardia Lamblia Symptoms

  • Acute giardiasis: Incubation period is 1-3 weeks (average 12-20 days). Symptoms include diarrhea (often foul-smelling with fat and mucus), abdominal pain, bloating, belching, flatulence, and vomiting.
  • Chronic giardiasis: May occur with or without a prior acute episode. Symptoms can include chronic diarrhea, malabsorption of fat, vitamins, and sugars; weight loss; and a sprue-like syndrome.

Giardia Lamblia Diagnosis

  • Microscopic examination of stool: Identifying oval cysts or motile trophozoites in stool samples. Wet mounts with saline or iodine are used for specimen preparation. Stool specimens may have a noticeable odour, pale colour, and float in water.
  • Antigen detection assays (ELISA and IFA): Detecting antigens from Giardia in stool samples to identify presence of parasites.
  • Duodenal contents examination (aspiration and biopsies): Examining the upper small intestine for the presence of the parasite.
  • Entero-test (string test): Using a capsule-and-thread device to obtain duodenal fluid for examination.
  • Molecular methods (PCR): Detecting Giardia DNA in stool samples for confirmation.

Giardia Lamblia Treatment

  • Metronidazole (250 mg 3 times daily for 5-7 days)
  • Tinidazole (2 g orally, once)
  • Others: Furazolidone, and Nitazoxamide (for children), Parmomycin (for pregnant females)

Giardia Lamblia Prevention

  • Proper sanitation and wastewater disposal.
  • Handwashing before eating.
  • Proper diaper disposal.
  • Considering boiling or filtering drinking water in at-risk areas.
  • Treating symptomatic cases to prevent spread.

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Medical Parasitology - Lecture 3: Giardia lamblia PDF

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