36 Questions
What is the primary vector responsible for transmitting the Rhodesian strain of trypanosomiasis?
Tsetse fly
What is the primary reservoir of the Trypanosoma brucei rhodesiense parasite?
Infected wild animals and humans
What is the disease caused by the Leishmania parasite?
Cutaneous Leishmaniasis
What is the estimated number of people affected by Leishmaniasis?
12 million
What is a common symptom of the late stage of African Sleeping Sickness?
Indifference to environment
What is the vector responsible for transmitting Leishmaniasis?
Sand fly
What is the primary function of a vector in the context of parasitic life cycles?
To transmit a disease organism from one host to another
What is the term for the host in which the terminal stage of the parasite occurs?
Definitive host
What is unique about the organelle found in Phylum Euglenozoa?
It is a modified mitochondrion
Which of the following is NOT a characteristic of Phylum Euglenozoa?
Being photosynthetic
What is the disease caused by the parasite Leishmania?
Leishmaniasis
What is the shape of the amastigote parasite?
Spherical
Which of the following parasites is responsible for causing Chagas disease and sleeping sickness?
Trypanosoma
What is the direction of the flagellum in relation to the organism's interior end?
The flagellum pulls the organism in the opposite direction of the interior end
Where is the kinetoplast typically located in an amastigote?
Near the nucleus
What is the term for the stage of the parasite that occurs in the reservoir host?
Partial development
What is the characteristic of the amastigote stage?
Non-motile and intracellular
Which disease is associated with the promastigote parasite?
African sleeping sickness
What is the typical location of the kinetoplast in a promastigote?
At the anterior end
What is the estimated number of people affected by African sleeping sickness?
60 million
When did the number of cases of African sleeping sickness start to increase?
Mid-1960s
What is the approximate number of reported cases of African sleeping sickness in 1998?
100,000-500,000
Which of the following is a characteristic of Giardia lamblia?
It inhabits the intestines of several animals and humans
What is the primary method of acquiring Giardia lamblia?
By drinking water with cysts
What is the primary characteristic of the phylum Apicomplexa?
Presence of complex organelles for penetrating host cells
What is the disease caused by Toxoplasma gondii?
Toxoplasmosis
What is the primary vector of malaria?
Mosquito of genus Anopheles
What is the most widespread and dangerous form of malaria?
P.falciparum
What is the infectious stage of the malaria parasite transmitted through a mosquito bite?
Sporozoites
What is the process by which merozoites produce more merozoites in the liver?
Schizogony
What is the characteristic feature of Cercozoans?
Thread-like pseudopodia
What is the mode of nutrition in Amoebas?
Holozoic
What is the disease caused by Entamoeba histolytica?
Amebic dysentery
What is the process by which gametes unite to form oocysts in the mosquito's stomach?
Fertilization
What is the characteristic feature of Amoebozoans?
Lobe-shaped pseudopodia
What is the habitat of Gymnamoebas?
Soil and aquatic environments
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).
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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