Toxoplasma Gondii

Question 1

Classification of toxoplasma gondii

Answer 1

Kingdom protozoa
Phylum sporozoa
Class coccidia
Order emiritida

Question 2

Habitat of t gondii

Answer 2

Obligate intracellular parasite found in re cells

Question 3

Morphology of t gondii

Answer 3

1. Tachyzoite stage
2. Tissue cyst
3. Oocyst
   All these stages are infectious to man

Question 4

What does the term ‘Toxoplasma’ mean?

Answer 4

‘Toxoplasma’ comes from ‘taxon’ meaning ‘bow’ and ‘plasma’ meaning ‘form’, relating to the crescent shape of the tachyzoite stage of the parasite

Question 5

To which kingdom and phylum does Toxoplasma gondii belong?

Answer 5

Toxoplasma gondii belongs to the kingdom Protozoa and phylum Sporozoa

Question 6

What are the definitive hosts of Toxoplasma gondii?

Answer 6

Members of the cat family, Felidae, are the only known definitive hosts for the sexual stage of T. gondii

Question 7

What percentage of individuals are estimated to be exposed to T. gondii during their lives?

Answer 7

Upto 70% of all individuals are exposed to T. gondii at some point during their lives

Question 8

What type of parasite is Toxoplasma gondii?

Answer 8

T. gondii is an obligate intracellular parasite

Question 9

List the important stages of the T. gondii life cycle.

Answer 9

• Tachyzoites
• Tissue cysts
• Oocysts

Question 10

What is the shape and size of the tachyzoite?

Answer 10

The tachyzoite is crescent-shaped, measuring 6 μm in length and 2 μm in breadth

Question 11

What is a pseudocyst in the context of T. gondii?

Answer 11

Groups of proliferating tachyzoites within a host cell are known as pseudocysts

Question 12

What are tissue cysts and where do they occur?

Answer 12

Tissue cysts occur in chronic infection when parasites multiply and produce a wall within a host cell

Question 13

What are bradyzoites?

Answer 13

Bradyzoites are the slowly multiplying forms of the trophozoites contained in tissue cysts

Question 14

What is the size and structure of an oocyst?

Answer 14

The oocyst is oval, 10-12 μm in diameter, and contains a sporoblast with a wall that has two colourless layers

Question 15

What are the two cycles of T. gondii’s life cycle?

Answer 15

• Enteric cycle
• Exoenteric cycle

Question 16

What occurs during the enteric cycle of T. gondii?

Answer 16

Schizogony and gamatogony occur within the mucosal epithelial cells of the small intestine of definitive hosts

Question 17

How does a cat acquire T. gondii infection?

Answer 17

By ingestion of tachyzoites, bradyzoites from tissue cysts, or sporozoites from oocysts in cat faeces

Question 18

Fill in the blank: Humans acquire T. gondii infection primarily through ingestion of contaminated food and drinks or undercooked _______.

Answer 18

meat

Question 19

What underlying conditions may influence the outcome of T. gondii infection?

Answer 19

• Various types of malignancies
• Collagen vascular disease
• Organ transplantation
• AIDS

Question 20

What is the most common cause of secondary CNS infection in patients with AIDS?

Answer 20

T. gondii is the most common cause of secondary CNS infection in patients with AIDS

Question 21

What specimens are used for laboratory diagnosis of T. gondii?

Answer 21

• Blood
• Sputum
• Bone marrow
• CSF
• Biopsy material from lymph node, spleen, and brain

Question 22

What method can be used to isolate T. gondii in the lab?

Answer 22

Inoculation of tissue culture

Question 23

What is the primary treatment for toxoplasmic encephalitis?

Answer 23

• Pyrimethamine
• Sulphadiazine
• Folinic acid

Question 24

True or False: There is an effective vaccine for T. gondii.

Answer 24

False

Question 25

List three recommended prevention measures for toxoplasmosis.

Answer 25

• Avoidance of contact with cat faeces and uncooked meat
• Proper cooking of meat
• Thorough washing of hands and surfaces that come in contact with uncooked meat