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Questions and Answers
What is the feeding and reproducing stage of a protozoan called?
What is the feeding and reproducing stage of a protozoan called?
Which of the following is a primary reservoir for Trypanosoma cruzi, the causative agent of Chagas' disease?
Which of the following is a primary reservoir for Trypanosoma cruzi, the causative agent of Chagas' disease?
What happens during the process of excystment in protozoan parasites?
What happens during the process of excystment in protozoan parasites?
What severe condition is associated with invasive amoebic dysentery caused by amoebae?
What severe condition is associated with invasive amoebic dysentery caused by amoebae?
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Which stage of African Trypanosomiasis is associated with mental deterioration and neurological problems?
Which stage of African Trypanosomiasis is associated with mental deterioration and neurological problems?
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What is the primary method of preventing disease transmission from tsetse flies?
What is the primary method of preventing disease transmission from tsetse flies?
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Which statement regarding Leishmania is true?
Which statement regarding Leishmania is true?
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What distinguishes Plasmodium falciparum among the malaria-causing parasites?
What distinguishes Plasmodium falciparum among the malaria-causing parasites?
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How does Toxoplasma affect behavior in infected rats?
How does Toxoplasma affect behavior in infected rats?
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Which of the following is a characteristic of trematodes?
Which of the following is a characteristic of trematodes?
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What is a common result of Ascaris lumbricoides infection?
What is a common result of Ascaris lumbricoides infection?
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How does Ancylostoma duodenale typically enter the human body?
How does Ancylostoma duodenale typically enter the human body?
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What behavior change can Toxoplasma induce in infected men compared to women?
What behavior change can Toxoplasma induce in infected men compared to women?
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Study Notes
Parasitology: Protozoan and Helminthic Parasites
- Emerging as serious threats in developed nations
- Parasites infect humans via ingestion, vectorborne transmission, or direct contact
- Arthropod vectors carry microbial pathogens
- Protozoa are unicellular eukaryotes
Protozoan Parasites of Humans
- Trophozoite: Feeding and reproducing stage within the host
- Cyst: Infective form; survives in the environment; develops into trophozoites after ingestion
- Parasites grouped by locomotion: ciliates, amoebae, flagellates, apicomplexans
Amoebae
- Water sources: Few cause disease
- Drinking contaminated water
- Excystment in small intestine; trophozoites migrate to large intestine
- Invasive amebic dysentery (severe diarrhea)
- Naegleria fowleri: Inhaled by swimmers; infects nasal mucosa, travels to the brain, feeding on brain tissue; 37 infections (2006-2015)
Flagellates
- Trypanosoma cruzi: Causes Chagas disease
- Opossums and armadillos are primary reservoir
- Feeds preferentially on blood vessels in the lips
- Myocarditis, asymptomatic chronic stage, congestive heart failure
- Leading cause of death in Latin America
- African Trypanosomiasis.
- Causative agent: Trypanosoma brucei gambiense
Other Protozoan Diseases
- Leishmania: Fatal in 95% of untreated cases
- Giardia: Ranges from asymptomatic infection to gastrointestinal disease
- Hydrogen sulfide detected in breath/stools; beavers are a common reservoir
- Trichomonas vaginalis: Most common protozoan causing human disease in industrialized nations; transmitted almost exclusively via sex; treated with nitroimidazole drugs
- Plasmodium vivax: Fever every 2 days
- Plasmodium falciparum: Most deadly
- Anopheles mosquitoes transmit Plasmodium
- Parasite hidden from immune system while in erythrocytes;
- Induces "bite me" chemical signal in humans
- Genetic traits increase malaria resistance (sickle-cell trait)
- Death of brain tissue can be fatal within 24 hours
- Toxoplasma: Cats are the definitive host; alters rat behavior to be attracted to cat urine; may alter human behavior (men:introverted, suspicious; women: extraverted, trusting)
Helminths
- Toxoplasmosis: More severe in AIDS patients and fetuses; transplacental transfer can cause abortion, stillbirth, or various birth defects
- Macroscopic: 3 groups: Cestodes, Trematodes, Nematodes
- Cestodes (tapeworms): -Taenia saginata: Beef tapeworm -Taenia solium: Pork tapeworm -Diphyllobothrium latum: Fish tapeworm
- Trematodes (flukes): -Fasciola hepatica: Accidental definitive hosts in humans (blood, liver, lung, intestinal) -Schistosoma: Humans are the principal definitive host
- Nematodes (roundworms): -Ascaris lumbricoides: Most common nematode infection of humans -Enterobius vermicularis: (pinworms); usually asymptomatic; highly infectious -Ancylostoma duodenale: (hookworm) enters through feet; anemia, weakness, craving for peculiar foods (pica) -Trichinella spiralis: (trichinellosis), forms cysts in muscle tissue; encysted larvae ingested from undercooked pork and other meats
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Description
Explore the fascinating world of protozoan and helminthic parasites. This quiz covers their life cycles, modes of transmission, and the diseases they can cause in humans. Test your knowledge on the emerging threats posed by these parasites in developed nations.
