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Questions and Answers
What is the primary route of transmission for Entamoeba histolytica?
What is the primary route of transmission for Entamoeba histolytica?
Which symptom is NOT associated with intestinal amebiasis caused by Entamoeba histolytica?
Which symptom is NOT associated with intestinal amebiasis caused by Entamoeba histolytica?
Which of the following factors does NOT belong to the host in relation to susceptibility to parasite infection?
Which of the following factors does NOT belong to the host in relation to susceptibility to parasite infection?
What describes cyst passers in relation to Entamoeba histolytica?
What describes cyst passers in relation to Entamoeba histolytica?
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Which of the following is an example of a urogenital flagellate?
Which of the following is an example of a urogenital flagellate?
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What defines a visiting ectoparasite?
What defines a visiting ectoparasite?
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Which type of host harbors the adult stages of a parasite?
Which type of host harbors the adult stages of a parasite?
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What characterizes a heteroxenous parasite?
What characterizes a heteroxenous parasite?
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Which type of endoparasite has a simple life cycle involving only one host?
Which type of endoparasite has a simple life cycle involving only one host?
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What is the role of a vector in the context of parasitology?
What is the role of a vector in the context of parasitology?
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Study Notes
Ectoparasites
- Organisms that live on the outside of their host (skin, feathers, hairs, gills).
- Types:
- Visiting: Visit hosts for blood meals (e.g., fleas, mosquitoes)
- Temporary: Remain attached for short periods (e.g., some leeches)
- Permanent: Remain attached for their entire life (e.g., ticks, mites)
Endoparasites
- Organisms that live within their host's body (gut, cavities, lungs, body fluids).
- Types:
- Homoxenous/Monoxenous: Use only one host during their life cycle.
- Heteroxenous: Require multiple hosts (often different phyla) to complete development.
- Heterogenetic: Have alternating parasitic and free-living generations.
- Heterogenic: Alternation of generations where one reproduces sexually and gives rise to the other generation which reproduces asexually.
Hosts
- Definitive/Primary Host: Hosts that harbor the adult parasite stages and where the parasite may reproduce sexually.
- Intermediate Host: Hosts that harbor the larval or juvenile stage of the parasite.
- Reservoir Host: Hosts that harbor the adult parasite without being harmed.
- Transport Host: Hosts that carry the parasite, but the parasite doesn't develop in this host.
- Vector: Hosts that transmit the parasite to other hosts.
Factors Affecting Host Susceptibility
-
Host Factors:
- Age
- Physiological status
- Genetic factors
-
Parasite Factors:
- Dose of infective stage
- Viability of infective stage
- Species of parasite
- Site of parasite development
- Genetic factors
Modes of Transmission (e.g., Entamoeba histolytica)
- Fecal-oral route (most common): Ingestion of contaminated food or water with mature quadrinucleated cysts.
- Infective form: Mature quadrinucleated cyst
Pathology and Symptomatology (e.g., Intestinal Amebiasis)
- Intestinal Amebiasis: Ulcers, dysentery, fever, colic, frequent motions in acute cases; disappear in chronic cases.
- Extraintestinal Amebiasis: Trophozoites carried to organs, causing abscesses (liver, brain etc).
- Cyst Passers: Individuals with parasites that pass cysts in stool without symptoms.
Intestinal (Non-Pathogenic) Amebae
- Entamoeba dispar, Endolimax nana, Entamoeba coli, Entamoeba hartmanni, Entamoeba polecki, Iodamoeba butschlii.
Species living in the small/large intestine
- (Examples too numerous to list; they are highly specific parasite species to particular hosts, so don't expect a perfect list of examples).
Urogenital Flagellates (e.g., Trichomonas vaginalis)
- Found in the urogenital tract, often affecting vagina in women and urethra in men.
Hemoflagellates (Blood Flagellates; e.g., Leishmania spp. and Trypanosoma spp.)
- Live in the blood and/or tissues of humans, causing several diseases.
Trypanosoma spp. (African Trypanosomiasis)
- Transmitted by tsetse flies (Genus Glossina) through the saliva.
- The tsetse fly carries the parasite, and after infecting the mammal, undergoes multiplication by binary fission.
- Affects the lymphatic and circulatory system.
- Has two sub-species (T. brucei gambiense and T. brucei rhodesiense)
- Control and prevention include minimizing contact with tsetse flies, wearing appropriate clothing, insect repellents. There is no vaccine/drug for prophylaxis.
Leishmania spp.
- Causes cutaneous, mucocutaneous, and visceral forms of leishmaniasis.
- Transmitted by sand flies.
Balantidium coli (Ciliophora)
- Only species of Ciliophora that parasitizes man.
- Lives in the large intestine of pigs.
- Nonpathogenic to pigs.
- Causes balantidiasis (balantidial dysentery).
- Transmitted by ingestion of cysts.
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Description
Explore the fascinating world of parasites with this quiz that covers both ectoparasites and endoparasites. Learn about their types, life cycles, and the different hosts they inhabit. Test your knowledge on the complex relationships between parasites and their hosts.
