Parasitic Life Cycle and Vectors
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Questions and Answers

What is the primary vector responsible for transmitting the Rhodesian strain of trypanosomiasis?

  • Sand fly
  • Flea
  • Mosquito
  • Tsetse fly (correct)
  • What is the primary reservoir of the Trypanosoma brucei rhodesiense parasite?

  • Infected humans
  • Contaminated water
  • Infected livestock
  • Infected wild animals and humans (correct)
  • What is the disease caused by the Leishmania parasite?

  • Cutaneous Leishmaniasis (correct)
  • Trypanosomiasis
  • African Sleeping Sickness
  • Malaria
  • What is the estimated number of people affected by Leishmaniasis?

    <p>12 million</p> Signup and view all the answers

    What is a common symptom of the late stage of African Sleeping Sickness?

    <p>Indifference to environment</p> Signup and view all the answers

    What is the vector responsible for transmitting Leishmaniasis?

    <p>Sand fly</p> Signup and view all the answers

    What is the primary function of a vector in the context of parasitic life cycles?

    <p>To transmit a disease organism from one host to another</p> Signup and view all the answers

    What is the term for the host in which the terminal stage of the parasite occurs?

    <p>Definitive host</p> Signup and view all the answers

    What is unique about the organelle found in Phylum Euglenozoa?

    <p>It is a modified mitochondrion</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Phylum Euglenozoa?

    <p>Being photosynthetic</p> Signup and view all the answers

    What is the disease caused by the parasite Leishmania?

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

    What is the shape of the amastigote parasite?

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

    Which of the following parasites is responsible for causing Chagas disease and sleeping sickness?

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

    What is the direction of the flagellum in relation to the organism's interior end?

    <p>The flagellum pulls the organism in the opposite direction of the interior end</p> Signup and view all the answers

    Where is the kinetoplast typically located in an amastigote?

    <p>Near the nucleus</p> Signup and view all the answers

    What is the term for the stage of the parasite that occurs in the reservoir host?

    <p>Partial development</p> Signup and view all the answers

    What is the characteristic of the amastigote stage?

    <p>Non-motile and intracellular</p> Signup and view all the answers

    Which disease is associated with the promastigote parasite?

    <p>African sleeping sickness</p> Signup and view all the answers

    What is the typical location of the kinetoplast in a promastigote?

    <p>At the anterior end</p> Signup and view all the answers

    What is the estimated number of people affected by African sleeping sickness?

    <p>60 million</p> Signup and view all the answers

    When did the number of cases of African sleeping sickness start to increase?

    <p>Mid-1960s</p> Signup and view all the answers

    What is the approximate number of reported cases of African sleeping sickness in 1998?

    <p>100,000-500,000</p> Signup and view all the answers

    Which of the following is a characteristic of Giardia lamblia?

    <p>It inhabits the intestines of several animals and humans</p> Signup and view all the answers

    What is the primary method of acquiring Giardia lamblia?

    <p>By drinking water with cysts</p> Signup and view all the answers

    What is the primary characteristic of the phylum Apicomplexa?

    <p>Presence of complex organelles for penetrating host cells</p> Signup and view all the answers

    What is the disease caused by Toxoplasma gondii?

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

    What is the primary vector of malaria?

    <p>Mosquito of genus Anopheles</p> Signup and view all the answers

    What is the most widespread and dangerous form of malaria?

    <p>P.falciparum</p> Signup and view all the answers

    What is the infectious stage of the malaria parasite transmitted through a mosquito bite?

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

    What is the process by which merozoites produce more merozoites in the liver?

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

    What is the characteristic feature of Cercozoans?

    <p>Thread-like pseudopodia</p> Signup and view all the answers

    What is the mode of nutrition in Amoebas?

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

    What is the disease caused by Entamoeba histolytica?

    <p>Amebic dysentery</p> Signup and view all the answers

    What is the process by which gametes unite to form oocysts in the mosquito's stomach?

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

    What is the characteristic feature of Amoebozoans?

    <p>Lobe-shaped pseudopodia</p> Signup and view all the answers

    What is the habitat of Gymnamoebas?

    <p>Soil and aquatic environments</p> Signup and view all the answers

    Study Notes

    Parasitic Life Cycle

    • A vector is a carrier, especially an animal, that transmits a disease organism from one host to another.
    • An intermediate host is one that alternates with the definitive host.
    • A definitive host is one in which the terminal (frequently sexual) stage of the parasite occurs.
    • A reservoir host is a definitive host in which the parasite passes through partial development, but not to sexual maturity.

    Phylum Euglenozoa

    • Possess flagella.
    • Formerly under Phylum Sarcomastigophora.
    • Subphylum Kinetoplasta has a unique organelle, the kinetoplast (modified mitochondrion).
    • All are parasites.

    Trypanosoma

    • Causes sleeping sickness and Chagas disease.
    • Has a morphological form called amastigote, which is spherical in shape, has no free flagellum, and is non-motile.
    • Another form is the promastigote, which has a free flagellum and is motile.
    • African sleeping sickness is a chronic disease that lasts for years, transmitted by the Tsetse fly (Glossina), and affects 60 million people in 36 nations.

    Leishmaniasis

    • Caused by Leishmania, which is transmitted by the sand fly (Phlebotomus).
    • Affects 12 million people.

    Phylum Retortamonada

    • Lack mitochondria and Golgi bodies.
    • Class Diplomonadea includes Giardia, which causes giardiasis, also known as backpackers' disease or beaver fever.
    • Giardia inhabits the intestines of several animals and humans, and is acquired by drinking water with cysts.

    Phylum Apicomplexa

    • Parasites of animals and some cause serious human diseases.
    • Apex contains complex organelles specialized for penetrating host cells and tissues.
    • Locomotory structures are less obvious.
    • Includes Toxoplasma gondii, which causes toxoplasmosis, and can infect cats, humans, mammals, and birds.
    • Malaria is characterized by chills, fever, and in most cases, coma leading to death, transmitted by the mosquito genus Anopheles (60 spp.).
    • Protozoan parasites include Plasmodium falciparum, P.vivax, P.malariae, and P.ovale.
    • Infectious stage is sporozoites.

    Malaria

    • Sporozoites from a mosquito bite enter the liver and undergo schizogony to make merozoites.
    • Merozoites enter RBCs and undergo schizogony to make more merozoites.
    • Merozoites rupture RBCs to invade other RBCs, causing the sudden chills and fever typical of malaria.

    The Amoebas

    • Formerly under Phylum Sarcodina (under Phylum Sarcomastigophora).
    • Shape of pseudopodia is used for classification.
    • Found in aquatic and moist environments.
    • Few are parasitic.

    Cercozoans

    • Have thread-like pseudopodia.
    • A newly recognized clade, Cercozoa, contains a diversity of species that are among the organisms referred to as amoebas.

    Amoebozoans

    • Have lobe-shaped, rather than thread-like, pseudopodia.
    • Include gymnamoebas, entamoebas, and slime molds.

    Gymnamoebas

    • Common unicellular amoebozoans in soil, freshwater, and marine environments.
    • Most gymnamoebas are heterotrophic.
    • Actively seek and consume bacteria, other protists.

    Entamoebas

    • Parasites of vertebrates and some invertebrates.
    • Entamoeba histolytica causes amebic dysentery in humans.
    • Life-threatening manifestations are hemorrhage, perforation, appendicitis, and tumor-like growths (amebomas).

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    Learn about the different stages of a parasite's life cycle and the role of vectors, such as animals, in transmitting diseases from one host to another. Understand the importance of vectors in the spread of parasitic diseases.

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