Toxoplasmosis

Question 1

What is the source of Toxoplasma gondii?

Answer 1

Waterborne and foodborne

Question 2

What are the stages of Toxoplasma gondii?

Answer 2

Asexual and sexual cycle

Question 3

Associate the following descriptions with either the asexual or sexual cycle
a. Definitive hosts
b. Intermediate hosts
c. Macro- and microgametes
d. Tachyzoites
e. Bradyzoites in tissue cysts
f. Sporozoites in oocysts

Answer 3

a. Sexual
b. Asexual
c. Sexual
d. Asexual
e. Asexual
f. Sexual

Question 4

What is the life cycle of Toxoplasma gondii?

Answer 4

Cats are infected by eating contaminated vertebrae -> oocyst hatches in GI tract of the cat and is shed in the feces -> cattle are infected via ingestion of fecal oocysts and water and vegetables contaminated -> humans are contaminated

Question 5

True or false: Pregnant women can pass the disease to their children

Answer 5

True

Question 6

What is the global distribution of Toxoplasma gondii?

Answer 6

Worldwide

Question 7

True or false: Toxoplasmosis is usually benign

Answer 7

True

Question 8

The acute stage comprises which form of the parasite?

Answer 8

Tachyzoites

Question 9

The latent stage of the infection comprises what form of the parasite?

Answer 9

Bradyzoites

Question 10

In which cases is toxoplasmosis not benign?

Answer 10

Immunocompromised patients and primary infection with T. gondii during pregnancy

Question 11

True or false: There is a higher incidence of transplacental infection in the 1st trimester than in the 3rd trimester

Answer 11

False

Question 12

True or false: Allograft organ recipients and patients on prolonged corticosteroid therapy are at a higher risk of infection

Answer 12

True

Question 13

Which surface antigen on tachyzoites binds to self-proteoglycans on host cells?

Answer 13

SAG

Question 14

Which cellular structures are found in tachyzoites?

Answer 14

Dense granules and rhoptries

Question 15

How do tachyzoites divide?

Answer 15

Endodyogeny

Question 16

Where are tachyzoites found?

Answer 16

In bradyzoites

Question 17

Where do bradyzoites reside?

Answer 17

Tissue cysts

Question 18

What cellular feature is found in bradyzoites?

Answer 18

Amylopectin granules

Question 19

In which group do bradyzoites reactivate into tachyzoites?

Answer 19

Immunosuppressed patients

Question 20

Which of these conditions favor tachyzoite-bradyzoite conversion or bradyzoite-tachyzoite conversion?
a. Low pH, nitric oxide
b. Lack of nitric oxide, lack of T cells and cytokines

Answer 20

a. Tachyzoite-bradyzoite
b. Bradyzoite-tachyzoite

Question 21

True or false: Oocysts are not viable in moist soil for up to 18 months

Answer 21

False

Question 22

How many sporocysts are contained in oocysts?

Answer 22

2

Question 23

Why are coccidian oocysts a problem?

Answer 23

The oocyst wall makes them resistant to desiccation and chemical disinfection

Question 24

What are oocysts resistant to?

Answer 24

UV, dessication, freezing, chemical agents

Question 25

True or false: When excreted, the oocyst is sporulated and infectious

Answer 25

False, it is unsporulated and non-infectious

Question 26

What are contained in the sporocysts?

Answer 26

Infectious sporozoites

Question 27

When do oocysts become infectious?

Answer 27

24-48 hours after shedding

Question 28

True or false: Oocyst shedding does not recur even after repeated exposure to the parasite

Answer 28

True

Question 29

True or false: Oocysts on cat fur are infectious

Answer 29

False

Question 30

True or false: Ocular toxoplasmosis occurs in children more than in elderly people

Answer 30

True

Question 31

What is the immune response against T. gondii in immunocompetent hosts?

Answer 31

Cell-mediated and humoral immunity

Question 32

What is the immune response during acute and chronic phase of toxoplasmosis?

Answer 32

CD8 T cells and CD4 T cells, NK cells, macrophages, IL-12 from Th1 response

Question 33

What is the major effector against T. gondii?

Answer 33

IFN-gamma

Question 34

Which antibodies are detected in acute infection?

Answer 34

IgG and IgM

Question 35

What is the diagnostic technique of toxoplasmosis?

Answer 35

Serology

Question 36

Which diagnostic method is better than serology?

Answer 36

ELISA

Question 37

Which treatments are for acute or chronic toxoplasmosis? a. Alovaquone, Clindamycin c. Pyrimethamine, Sulfadiazine, Spiramycin

Answer 37

a. Chronic b. Acute

Question 38

True or false: Treatment for the disease is not efficient due to the conversion of tachyzoites to bradyzoites

Answer 38

True