Protozoa: Medical Importance
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Questions and Answers

What is the most common manifestation of extraintestinal amebiasis?

  • Brain abscess
  • Pleuropulmonary abscess
  • Amoebic liver abscess (correct)
  • Necrotic lesions on the skin

Which of the following is primarily responsible for the asexual reproduction of ciliates?

  • Conjugation
  • Budding
  • Binary fission (correct)
  • Autogamy

Which organism is the only known human parasite among the ciliates?

  • Amoeba proteus
  • Entamoeba histolytica
  • Amoebic granuloma
  • Balantidium coli (correct)

What structure in Balantidium coli leads to the cytostome or mouth?

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

What typically happens after conjugation in ciliates?

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

In the context of Balantidium coli, what does the cyst stage primarily have in terms of visibility?

<p>Both nuclei and cilia (B)</p> Signup and view all the answers

Which complication may result from severe chronic infections of Entamoeba histolytica?

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

What role do micronuclei play in ciliates?

<p>Necessary for reproduction (A)</p> Signup and view all the answers

What characteristic distinguishes protozoans from multicellular organisms?

<p>They exist as solitary cells or cell colonies. (A)</p> Signup and view all the answers

What mode of nutrition is common among protozoans?

<p>Heterotrophic (A)</p> Signup and view all the answers

Which protozoan is known to be a pathogenic species in humans?

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

What feature is primarily used by amoebas for movement?

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

How many nuclei can the cysts of E. coli possess?

<p>Eight (A)</p> Signup and view all the answers

What type of environment do protozoans predominantly inhabit?

<p>Moist and aquatic habitats (A)</p> Signup and view all the answers

Which of the following is NOT a major group of protozoans based on locomotion?

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

What is the primary characteristic of Entamoeba cells?

<p>They contain a single nucleus. (B)</p> Signup and view all the answers

What is a potential complication of acute infections that can lead to life-threatening consequences?

<p>Perforation of the colon (D)</p> Signup and view all the answers

In what context is extraintestinal infection considered serious?

<p>As a secondary complication to intestinal infection (B)</p> Signup and view all the answers

What might be a reason for severe symptoms in infected individuals?

<p>Debilitation or immunocompromised state (D)</p> Signup and view all the answers

Which of the following treatments is NOT listed for acute infections?

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

How do Plasmodium species primarily complete their life cycle?

<p>Developing in a blood-feeding insect host (B)</p> Signup and view all the answers

What happens to red blood cells during a Plasmodium infection?

<p>They are destroyed (D)</p> Signup and view all the answers

Which of the following species of Plasmodium is known to infect humans regularly?

<p>P. vivax (A)</p> Signup and view all the answers

Which mosquito genus is primarily associated with the transmission of Plasmodium species?

<p>Anopheles (A)</p> Signup and view all the answers

What is the primary mode of reproduction for the trophozoite of Entamoeba histolytica?

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

Which of the following statements is true regarding cysts formed by Entamoeba species?

<p>Cysts vary in size and number of nuclei depending on the species. (D)</p> Signup and view all the answers

Where are pathogenic Entamoeba species most commonly found?

<p>In fresh water contaminated with human faeces. (D)</p> Signup and view all the answers

What is the most common manifestation of invasive amoebiasis?

<p>Amoebic liver abscess (D)</p> Signup and view all the answers

Who is considered at higher risk for amoebiasis?

<p>Men who have sex with men and immunocompromised persons. (D)</p> Signup and view all the answers

What is required to cause amoebic dysentery in animal models?

<p>1-100 cysts (D)</p> Signup and view all the answers

What is the infectious stage of E.histolytica?

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

What makes E.histolytica a classified category B biodefense pathogen?

<p>Its low infectious dose and environmental stability. (C)</p> Signup and view all the answers

What is the primary reservoir for Balantidium coli?

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

How is balantidiasis typically transmitted to humans?

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

What triggers the encystation of trophozoites in Balantidium coli?

<p>Dehydration of intestinal contents (B)</p> Signup and view all the answers

What role do proteolytic enzymes play in the life cycle of Balantidium coli?

<p>They help trophozoites invade the colon wall. (C)</p> Signup and view all the answers

Which population is at higher risk of infection by Balantidium coli?

<p>Malnourished individuals with low stomach acidity (B)</p> Signup and view all the answers

What happens to the cyst of Balantidium coli once ingested by the host?

<p>It forms a protective layer. (C)</p> Signup and view all the answers

What percentage of the human population is affected by balantidiasis?

<p>Less than 1% (A)</p> Signup and view all the answers

In which part of the gastrointestinal tract does encystation of Balantidium coli primarily occur?

<p>Distal large intestine (C)</p> Signup and view all the answers

What is the primary mode of transmission for Entamoeba histolytica?

<p>Ingestion of mature cysts from contaminated sources (B)</p> Signup and view all the answers

What occurs during the excystation process in the life cycle of Entamoeba histolytica?

<p>Cysts are converted into mature trophozoites (B)</p> Signup and view all the answers

Which syndrome is associated with invasive intestinal amoebiasis?

<p>Secretory bloody diarrhea and colitis (D)</p> Signup and view all the answers

How do trophozoites of Entamoeba histolytica reproduce?

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

What is the most common site of extraintestinal amoebiasis?

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

What best describes asymptomatic carriers of Entamoeba histolytica?

<p>They continue to pass cysts in their stool. (B)</p> Signup and view all the answers

Which factor contributes to the survival of cysts of Entamoeba histolytica in the external environment?

<p>The protective walls that encase them (D)</p> Signup and view all the answers

What characterizes amoebic colitis?

<p>Invasion of the mucosa leading to inflammation (A)</p> Signup and view all the answers

Flashcards

Entamoeba histolytica

A pathogenic amoeba species that can cause amoebic dysentery in humans.

Amoeboid Movement

A method of movement for some protozoa using pseudopodia (false feet).

Entamoeba species

Group of amoeba species that live in the human gut; some are pathogenic.

Pseudopodia

Temporary extensions of cytoplasm used for movement and feeding in some protozoa.

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Heterotrophic

Obtaining energy by consuming other organisms.

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Protozoa

Single-celled eukaryotic organisms.

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Eukaryotes

Cells containing a nucleus.

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Amoeba

A protozoan that moves using pseudopodia.

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Amoebiasis transmission

Contaminated food, water, or hands transmits the cystic form of Entamoeba histolytica.

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Trophozoite

The feeding and dividing form of Entamoeba histolytica, typically 10-20µm

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Entamoeba cyst

Infective stage; a dormant form of the parasite for transmission through the environment.

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Amoebiasis symptoms

Can be asymptomatic or cause dysentery, liver abscess, other invasive diseases.

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Binary fission

The way trophozoites reproduce, dividing into two smaller cells.

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Infective dose (amoebiasis)

Only 1-100 cysts needed to cause dysentery in animal models.

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Risk groups (amoebiasis)

Developing countries, immunocompromised, institutionalized populations, and travellers.

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Balantidium coli

A large ciliated protozoan that can cause intestinal infections in humans.

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Ciliates

Single-celled organisms that have cilia, small hair-like structures for movement and feeding.

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Macronucleus

A large nucleus in ciliates that controls metabolic and developmental functions.

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Micronucleus

The smaller nucleus in ciliates, responsible for sexual reproduction.

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Cyst

The dormant, resistant stage of Balantidium coli, used for transmission.

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Peristome

The opening at the anterior end of Balantidium coli that leads to the mouth.

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What distinguishes Balantidium coli from other ciliates?

It is the only known ciliate that can infect humans.

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Amoebiasis

A disease caused by the parasitic amoeba Entamoeba histolytica. It can manifest in two main forms: dysentery and liver abscesses.

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Cysts vs. Trophozoites

Cysts are the dormant, resistant form of E. histolytica that can survive outside the body. Trophozoites are the active, invasive form that causes disease.

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How is E. histolytica spread?

Infection occurs through the ingestion of mature cysts from contaminated food, water, or hands. It can also spread through direct contact with feces during sexual practices.

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Excystation

The process where the dormant cyst changes into the active trophozoite in the intestines.

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Luminal Amoebiasis

A non-invasive form of amoebiasis where E. histolytica stays in the intestinal lumen, often without symptoms.

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Amoebic Colitis

An invasive form of amoebiasis where E. histolytica invades the intestinal mucosa, causing bloody diarrhea and inflammation.

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Extraintestinal Amoebiasis

Complications of invasive amoebiasis where the trophozoites spread to other organs, most commonly the liver.

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Erythrophagocytosis

The process where E. histolytica engulfs and digests red blood cells, a characteristic feature for identifying it.

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Balantidiasis

A zoonotic disease caused by the ciliated protozoan Balantidium coli, typically acquired through contaminated water or food.

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B. coli life cycle

Starts with ingestion of a cyst, which releases trophozoites in the small intestine. Trophozoites colonize the large intestine, reproduce, and form new cysts.

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Where does B. coli thrive?

It lives in the large intestine, feeding on intestinal flora. Some trophozoites may invade the colon wall, causing ulcers.

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How does B. coli spread?

Through the fecal-oral route, mainly via contaminated water or food.

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Who is most at risk for Balantidiasis?

People with malnutrition (low stomach acidity) or compromised immune systems are more susceptible.

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Balantidium coli vs. other ciliates

It is the only known ciliated protozoan that can infect humans.

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What is encystation?

The process where B. coli trophozoites form resistant cysts, typically triggered by dehydration.

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Transmission of B. coli

It is primarily transmitted through contaminated water, particularly in areas where sanitation is poor and pigs are raised.

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Balantidium coli Transmission

Spread through ingesting cysts in contaminated water or food, or through contact with feces.

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Balantidium coli Symptoms

Often asymptomatic. When present, may include diarrhea, abdominal pain, and dysentery, especially in immunocompromised people.

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Balantidium coli Treatment

Antibiotics like metronidazole and tetracycline, as well as iodoquinol.

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Plasmodium Species

Group of parasitic protozoans that cause malaria, with complex life cycles involving mosquitoes and humans.

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Plasmodium Life Cycle

Involves development in a mosquito, then transmission to a vertebrate, including humans. It infects liver cells and red blood cells, leading to malaria.

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Merogony (Plasmodium)

Asexual replication process occurring inside red blood cells, producing pigment hemozoin as a byproduct of hemoglobin digestion.

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Impact of Plasmodium Infection

Destruction of red blood cells can cause malaria, a serious disease with symptoms like fever, chills, sweating, and anemia.

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Study Notes

PROTOZOA: MEDICAL IMPORTANCE

  • Protozoa are single-celled, heterotrophic eukaryotes found in moist environments.
  • They use organic carbon for energy.
  • They often possess flagella, cilia, or pseudopodia for movement.
  • Protozoa are grouped into Amoeba, Ciliates, Flagellates, Sporozoa, and Microspora, based on locomotion and reproduction.

AMOEBA (SARCODINA)

  • Amoeba use pseudopodia for movement.
  • Entamoeba, Naegleria, and Acanthamoeba are examples of medically important species.
  • Entamoeba are found in the gut of humans and animals.
  • E. histolytica is a pathogenic species causing amoebiasis.
  • Amoebiasis involves cysts and trophozoites in the faeces, and transmission via ingestion.

CILIATES (CILIOPHORA)

  • Ciliates use cilia for movement and feeding.
  • Balantidium coli is the only ciliate known to infect humans.
  • Balantidiasis is acquired through ingestion, and these organisms have a trophozoite, and a cyst stage.
  • Balantidiasis is transmitted through contaminated water or food.

SPOROZOA

  • Sporozoans undergo complex sexual and asexual reproduction.
  • Plasmodium species are medically important, causing malaria.
  • Malaria is spread by the bite of an infected mosquito.
  • Symptoms include fever and chills.
  • Parasites multiply in the red blood cells and liver.
  • There are several species of Plasmodium causing malaria including Falciparum, malariae, ovale, vivax and knowlesi.
  • Quinine, chloroquine and artemisinin combination therapies are among the treatment methods for malaria.

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Description

Explore the fascinating world of protozoa and their significance in medicine. This quiz covers different types of protozoa, such as amoebas and ciliates, along with their diseases and pathogenic potential. Assess your understanding of their structures, movements, and medical implications.

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