Biology: Toxoplasma Gondii

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Questions and Answers

What is the shape of oocysts of Toxoplasma gondii?

Round

Oval (correct)

Square

Triangular

Where are bradyzoites or cysts of Toxoplasma gondii typically found?

Bloodstream

Skeletal muscle and central nervous system (correct)

Lymph nodes

Liver

What is the duration of the acute phase of Toxoplasma gondii infection?

1-5 days

1-2 months

20-40 days

7-20 days (correct)

What is the impact of Toxoplasma gondii infection on immune-deficient individuals?

Death Signup and view all the answers

What is the form of Toxoplasma gondii present in the bloodstream?

Tachyzoite Signup and view all the answers

What is the characteristic of Toxoplasma gondii infection in immune-competent individuals?

Benign parasite Signup and view all the answers

What is the phase of Toxoplasma gondii infection caused by bradyzoites?

Chronic phase Signup and view all the answers

What is the number of sporozoites present in each sporocyst of Toxoplasma gondii?

4 Signup and view all the answers

What is the primary way in which Toxoplasma gondii is transmitted from the cat to the environment?

Through the cat's feces Signup and view all the answers

In which stage of the life cycle do sporoblasts divide to form sporocysts?

Zygote stage Signup and view all the answers

How many sporozoites are formed within each sporocyst?

4 Signup and view all the answers

What is the mode of transmission of Toxoplasma gondii from mother to fetus?

Congenital transmission Signup and view all the answers

What is the primary source of Toxoplasma gondii infection in humans?

Contaminated food Signup and view all the answers

What is the stage of the life cycle in which the parasite invades the mucosal cell of the small intestine of cats?

Sporozoite stage Signup and view all the answers

What is the definitive host of this organism?

Cat Signup and view all the answers

What is the shape of the tachyzoite?

One end is more rounded than the other Signup and view all the answers

What is the location of the nucleus in the tachyzoite?

Surrounded by the cell membrane Signup and view all the answers

What is the size range of the tachyzoite?

3-7 pm by 2-4 pm Signup and view all the answers

What is an intermediate host of this organism?

Humans, birds, ruminants, and rodents Signup and view all the answers

What is the function of the microneme?

Invasion of the host cell Signup and view all the answers

What is the function of the apicoplast?

Metabolic processes Signup and view all the answers

What is the function of the conoid complex?

Invasion of the host cell Signup and view all the answers

What is the definitive host of Toxoplasma gondii?

Cat Signup and view all the answers

What is the role of the rat and sparrow in the life cycle of Toxoplasma gondii?

Intermediate host Signup and view all the answers

How do humans typically become infected with Toxoplasma gondii?

Through consumption of contaminated crops, soil, and feces Signup and view all the answers

What is the form of Toxoplasma gondii that is found in cat feces?

Fecal oocyst (sporulated) Signup and view all the answers

What is the result of consuming undercooked meat infected with Toxoplasma gondii?

Ingestion of tissue cysts containing the parasite Signup and view all the answers

What is the tissue in which Toxoplasma gondii can form cysts?

Myocardium Signup and view all the answers

How do cats become infected with Toxoplasma gondii?

Through consumption of infected rodents Signup and view all the answers

What is the stage of the parasite that is infectious to humans?

Sporulated oocyst Signup and view all the answers

What is a common symptom of Toxoplasmosis in immunocompetent individuals?

Cervical lymphadenopathy Signup and view all the answers

Which of the following is NOT a symptom of Toxoplasmosis in pregnancy?

Cervical lymphadenopathy Signup and view all the answers

What is the primary method of diagnosis for Toxoplasmosis?

ELISA Signup and view all the answers

What is the treatment for Toxoplasmosis during pregnancy?

Spiramycin Signup and view all the answers

What is a common complication of Toxoplasmosis in infants?

All of the above Signup and view all the answers

Which of the following is NOT a treatment for Toxoplasmosis?

Azithromycin Signup and view all the answers

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.