Questions and Answers
What is the shape of oocysts of Toxoplasma gondii?
Where are bradyzoites or cysts of Toxoplasma gondii typically found?
What is the duration of the acute phase of Toxoplasma gondii infection?
What is the impact of Toxoplasma gondii infection on immune-deficient individuals?
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What is the form of Toxoplasma gondii present in the bloodstream?
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What is the characteristic of Toxoplasma gondii infection in immune-competent individuals?
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What is the phase of Toxoplasma gondii infection caused by bradyzoites?
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What is the number of sporozoites present in each sporocyst of Toxoplasma gondii?
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What is the primary way in which Toxoplasma gondii is transmitted from the cat to the environment?
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In which stage of the life cycle do sporoblasts divide to form sporocysts?
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How many sporozoites are formed within each sporocyst?
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What is the mode of transmission of Toxoplasma gondii from mother to fetus?
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What is the primary source of Toxoplasma gondii infection in humans?
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What is the stage of the life cycle in which the parasite invades the mucosal cell of the small intestine of cats?
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What is the definitive host of this organism?
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What is the shape of the tachyzoite?
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What is the location of the nucleus in the tachyzoite?
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What is the size range of the tachyzoite?
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What is an intermediate host of this organism?
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What is the function of the microneme?
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What is the function of the apicoplast?
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What is the function of the conoid complex?
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What is the definitive host of Toxoplasma gondii?
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What is the role of the rat and sparrow in the life cycle of Toxoplasma gondii?
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How do humans typically become infected with Toxoplasma gondii?
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What is the form of Toxoplasma gondii that is found in cat feces?
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What is the result of consuming undercooked meat infected with Toxoplasma gondii?
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What is the tissue in which Toxoplasma gondii can form cysts?
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How do cats become infected with Toxoplasma gondii?
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What is the stage of the parasite that is infectious to humans?
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What is a common symptom of Toxoplasmosis in immunocompetent individuals?
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Which of the following is NOT a symptom of Toxoplasmosis in pregnancy?
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What is the primary method of diagnosis for Toxoplasmosis?
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What is the treatment for Toxoplasmosis during pregnancy?
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What is a common complication of Toxoplasmosis in infants?
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Which of the following is NOT a treatment for Toxoplasmosis?
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Study Notes
Toxoplasma gondii
- T. gondii can infect all warm-blooded animals, including humans, and is a benign parasite in immune-competent individuals, but can cause death in immune-deficient people and fetuses.
- The parasite has two forms: tachyzoites (found in the blood) and bradyzoites (found in skeletal muscle and central nervous system).
Morphology
- Tachyzoites are typically 3-7 μm in size and have a single nucleus surrounded by a cell membrane.
- They have a unique shape, with one end often appearing more rounded than the other.
Transmission
- Intermediate hosts: humans, birds, ruminants, and rodents.
- Definitive host: cat.
- Transmission can occur through:
- Eating undercooked contaminated meat.
- Eating food contaminated by utensils, cutting boards, etc. that have come into contact with raw contaminated meat.
- Drinking water contaminated with cat feces.
- Contaminated meat handling without washing hands.
- Mother-to-fetus transmission (congenital).
- Blood transmission or organ transplantation.
Life Cycle
- In the cat (definitive host), the parasite forms schizonts and gametocytes, which then fuse to form zygotes, which develop into oocysts.
- The oocysts are excreted in the cat's feces and can contaminate soil, water, and food.
- In intermediate hosts (including humans), the parasite can form bradyzoites in tissue cysts.
Pathogenesis
- In immune-competent individuals, symptoms may include cervical lymphadenopathy, fatigue, chorioretinitis, and flu-like symptoms.
- In immunocompromised individuals, symptoms can include encephalitis, brain abscess, seizures, and retinochoroiditis.
- In pregnant women, infection can cause abortion, intrauterine death, and birth defects such as hydrocephalus, hepatomegaly, and cerebral calcification.
Diagnosis
- ELISA tests can detect IgM, IgG, and IgA antibodies.
- PCR can be used to detect the parasite's DNA.
Treatment
- Pyrimethamine + sulfadiazine or clindamycin + folinic acid can be used orally.
- Trimethoprine + sulfamethoxazole can be used via injection.
- During pregnancy, spiramycin is used.
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Description
This quiz covers the biology of Toxoplasma gondii, a parasitic protozoan. Test your knowledge of its characteristics, life cycle, and effects on hosts.
