Protozoa Biology Quiz

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Questions and Answers

What is one function of the cyst wall secreted by protozoa?

To promote rapid division

To attract other hosts

To help digest food

To resist unfavorable conditions (correct)

Which of the following is a type of asexual reproduction in protozoa?

Multiple fission (correct)

Conjugation

Gametogony

Syngamy

Where do protozoa primarily inhabit within their definitive host?

Jejunum

Stomach

Duodenum

Large intestine (correct)

Which of the following represents the infective stage of protozoa?

Mature quadri-nucleated cyst Signup and view all the answers

What characterizes the ectoplasm of protozoa?

Clear with pseudopodia Signup and view all the answers

Which type of sexual reproduction involves the exchange of nuclear material between organisms?

Conjugation Signup and view all the answers

What size range does the trophozoite stage of protozoa typically fall into?

15μm - 60μm Signup and view all the answers

Which organism is a common reservoir host for protozoa?

Dogs Signup and view all the answers

What is the primary form of locomotion for amoebae?

Pseudopodia Signup and view all the answers

Which component is NOT found inside the protoplasm of protozoa?

Cell wall Signup and view all the answers

What is the stage of protozoa characterized by a protective membrane?

Cyst Signup and view all the answers

How do ciliates primarily absorb nutrients?

Cytostome Signup and view all the answers

Which of the following protozoa is primarily classified as residing in the urogenital tract?

Trichomonas vaginalis Signup and view all the answers

What type of respiration do protozoa living in tissues and blood primarily use?

Aerobic Signup and view all the answers

Which type of nutrition involves ingesting solid particles?

Phagocytosis Signup and view all the answers

Which organism is associated with the bloodstream?

Plasmodium species Signup and view all the answers

Which method is used for morphological identification of E.histolytica?

Permanent stained smear Signup and view all the answers

What is one of the modes of transmission for this infection?

Consumption of contaminated foods or drinks Signup and view all the answers

What are Charcot-Leyden crystals associated with?

Chronic patients with E.histolytica Signup and view all the answers

Which serological test is considered the most sensitive for detecting amoebic liver abscesses?

Enzyme-linked immunosorbent assays Signup and view all the answers

What symptom is NOT commonly associated with severe cases of intestinal amebiasis?

Severe abdominal swelling Signup and view all the answers

Which organ is primarily affected in extra-intestinal amoebiasis due to trophozoite invasion?

Liver Signup and view all the answers

What is the infectious stage of E.histolytica?

Cyst Signup and view all the answers

Which of the following is a luminal amoebicide used in treatment?

Diloxanide furoate Signup and view all the answers

What is the purpose of cysteine proteinases secreted by trophozoites?

To penetrate the extracellular matrix Signup and view all the answers

What is the definitive host for E.histolytica?

Man Signup and view all the answers

What indicates the presence of intestinal amebiasis during a stool examination?

Identification of cysts or trophozoites Signup and view all the answers

Which of the following is NOT a complication of intestinal ulcers caused by amebiasis?

Skin rash Signup and view all the answers

Which diagnostic method is NOT typically used for identifying E.histolytica?

Electrocardiography Signup and view all the answers

What is a common preventive measure against E.histolytica infections?

Proper washing of vegetables Signup and view all the answers

What characterizes an ameboma?

Chronic granulomatous lesion Signup and view all the answers

How is autoinfection transmitted in amebiasis?

By hand-to-mouth contact Signup and view all the answers

What is the shape and size range of the cyst associated with balantidiasis?

Subspherical to oval, 52 to 55 µm Signup and view all the answers

Which of the following is NOT a mode of transmission for balantidiasis?

Airborne droplets Signup and view all the answers

What is the main component observed in the cytoplasm of the trophozoite that aids in movement and feeding?

Granular cytoplasm Signup and view all the answers

Which of the following clinical symptoms is NOT typically associated with severe balantidiasis?

Severe headache Signup and view all the answers

What is the first step in the laboratory diagnosis of balantidiasis?

Stool examination for detection of cysts Signup and view all the answers

Which of the following treatments is prescribed for adults suffering from balantidiasis?

Tetracycline 500 mg four times daily for 10 days Signup and view all the answers

What complication is associated with balantidiasis?

Intestinal perforation Signup and view all the answers

Which structure is characteristic of the cyst's wall in balantidiasis?

Double cyst wall with cilia visible in between Signup and view all the answers

Study Notes

Medical Protozoology

Protozoa are microscopic, single-celled organisms capable of all life functions.
Amoebas have a complex internal structure:
- Food vacuole
- Pseudopodia
- Plasmagel
- Plasmasol
- Ectoplasm
- Endoplasm
- Uroid
- Contractile vacuole
- Water vacuole
Protozoa have a relatively complex internal structure and carry out complex metabolic activities.
Protozoa's body consists of:
- Protoplasm, enclosed by a cell membrane
- Divided into outer ectoplasm and inner endoplasm,
- Nucleus, endoplasmic reticulum
- Food storage granules, contractile and digestive vacuoles.
The nucleus contains clumped or dispersed chromatin.
Locomotion by:
- Pseudopodia (amoebae)
- Cilia (ciliates)
- Flagella (flagellates)
- Undulant movement (sporozoa).

Life Cycle Stages of Protozoa

Trophozoites: actively feed and multiply.
Cysts: have a protective membrane, allow protozoa to survive outside the host, usually have resistant walls.

Classification of Protozoa

Small Intestine: Giardia lamblia
Large intestine: Entamoeba histolytica
Blood: Plasmodium species
Tissue: Toxoplasma gondii
Urogenital: Trichomonas vaginalis

Nutrition

Liquid food: Absorption through the body surface.
Solid particles:
- Pinocytosis (liquid form)
- Phagocytosis (using pseudopodia).
- Cytostome (flagellates or sporozoa, ciliates, amoeba)

Excretion

Excretion through contractile vacuoles rupturing to outside.
Some waste products are deposited in cytoplasm.
In sporozoa, waste is excreted as pigment.

Respiration

Aerobic: Protozoa living in tissues and blood.
Anaerobic: Protozoa living in the intestine lumen.

Secretion

Protozoa secrete digestive ferments, pigments.
Lytic enzymes help tissue lysis.
Toxins.
Cyst walls allow resistance from unfavorable conditions, transfer to other hosts without destruction.

Reproduction

Asexual reproduction:
- Simple fission: nucleus and cytoplasm divide into equal parts, forming two cells.
- Multiple fission: nucleus divides first into several parts, cytoplasm divides forming several small daughter cells.
Sexual reproduction:
- Conjugation: exchange of nuclear material between two organisms
- Gametogony: formation of male and female gametes, their union to form zygote.

Entamoeba histolytica

Geographical distribution: worldwide, areas with poor sanitation
Habitat: large intestine (caecum, colonic flexures, sigmoidorectal region).
Definitive host: Man
Reservoir host: Dogs, pigs, rats, monkeys
Infective stage: Mature cyst
Diagnostic stage: cyst and trophozoite
Trophozoite Size: 20µm (15-60μm)
Shape: Irregular
Cytoplasm: Differentiated into ectoplasm, endoplasm
Ectoplasm: Clear with a finger-like pseudopodia
Endoplasm: Granular, with nucleus, karyosome small and central
Spherical nucleus
Peripheral chromatin, uniform size, arranged on the inner surface of nuclear membrane
Food vacuoles: may contain RBCs (no bacteria)
Mature cyst (Quadrinucleate) Size: 15 um (10 - 20 um)
Shape: Rounded with thick cyst wall
Contents: one to four nuclei, glycogen vacuoles, chromatoid bodies

Mode of Transmission

Contaminated foods or drinks containing mature cysts.
Handling food by infected food handlers.
Flies and cockroaches that carry cysts to exposed food.
Autoinfection (faeco-oral or hand-to-mouth infection).

Life Cycle

Excystation in small intestine.
Trophozoite in large intestines.
Multiplication.
Cyst formation (mono-nucleated, bi-nucleated, quadri-nucleated.)
Extraintestinal spread (liver, lung, brain).

Pathogenesis and Symptomatology

Trophozoites secrete cysteine proteinases to invade extracellular matrix, host cell lysis and necrosis forming flask-shaped ulcers.
Amoeba spread from intestine to liver through portal circulation.
Ulcers may be complicated by secondary bacterial infections with necrosis, sloughing, perforation, peritonitis.

Clinical Pictures

Asymptomatic infections (cyst passers)
Symptomatic infections:
- Intestinal amebiasis (dysenteric or non-dysenteric colitis) -incubation period (1 week to 4 weeks)
- Clinical picture depends on parasite virulence factors and host immune response.
- Dysentery and diarrhea (up to 10 bowel movements).
- In severe cases: profuse diarrhea, fever, dehydration, electrolyte imbalance.
- Ameboma: chronic granulomatous lesion in the cecum or rectosigmoid junction.
Extraintestinal amebiasis:
- Liver, lung, brain abscesses.
- Skin Involvement (amebic cutis).

Diagnosis

Clinical and laboratory
- Microscopic: detects trophozoites (loose stools) or cysts (formed stools)
  - Direct smear of fresh stool samples.
  - Concentration methods (increase parasite detection).
  - Permanent stained smear (trichrome or iron hematoxylin).
  - Charcot-Leyden crystals (eosinophilic protein).
  - Sigmoidoscopy: visualize ulcer or trophozoites (in aspirate or biopsy).
Indirect: serodiagnosis (anti-amoebic antibody tests) including:
- Immunofluorescent antibody tests (IFAT)
- Indirect haemagglutination assays (IHAs)
- Radioimmunoassay (RIA).
- Enzyme-linked immunosorbent assays (ELISAs)
Stool antigen
Molecular diagnosis
- Radiological investigations (ultrasound or CT) detect complications.

Treatment

Medical treatment:
- Metronidazole (Flagyl) or Tinidazole (Fasigyn)
- Diloxanide furoate or Paromomycin, Luminal amoebicides (diloxanide furoate and iodoquinol).
Surgical treatment: rupturing abscess, intestinal perforation, and appendicitis.

Prevention and Control

Treatment of patients and carriers.
Proper washing of vegetables.
Sanitary sewer systems.
Avoid using human excreta as fertilizer.
Fly control.
Personal hygiene measures

Balantidium coli

Geographical distribution: worldwide, areas where pigs are raised and sanitation is inadequate.
Habitat: large intestine (caecum, colon).
Definitive host: Man.
Reservoir host: Pigs, less common monkey.
Infective stage: Mature cyst.
Diagnostic stage: cyst and trophozoite.
Trophozoite size: 60 × 45 µm, largest protozoon of man; Ovoid, tapers.
Covered with cilia.
Cytostome that extends to 1/3 of the body length.
Macronucleus (hyaline mass), micronucleus (small, spherical).
Granular cytoplasm, contractile vacuoles, food vacuoles (ingested microbes).
Cyst size: 52 to 55 μm.
Shape: Subspherical to oval.
Two nuclei (macronucleus and micronucleus)
Cytoplasm: granular, one or two contractile vacuoles
Double cyst wall. row of cilia between cyst wall layers.
Mode of transmission: similar to Entamoeba histolytica.
Life cycle: Multiplication by transverse binary fission, forming two young trophozoites. Cysts, excystation, multiplication, trophozoites in large and small intestine, pass in feces then to environment.
Complications: haemorrhage, secondary bacterial infection, appendicitis, intestinal perforation, and peritonitis.
Diagnosis: history, clinical picture, laboratory tests (stool examination, direct smear, concentration methods, permanent stains). Colonoscopy/sigmoidoscopy with biopsy.
Treatment: Tetracycline (adults 500 mg orally x 4 times daily for 10 days).
Prevention: care in handling pigs in pig farms, slaughter houses.

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Description

Test your knowledge on the fascinating world of protozoa! This quiz covers various aspects including their structure, reproduction, habitats, and nutrition modes. Dive deep into the biology of these single-celled organisms and discover how they thrive in different environments.