Toxoplasma Gondii

Question 1

What is the definitive hosts of Toxoplasma Gondii?

Answer 1

Domestic cats

Question 2

What are the intermediate hosts for Toxoplasma gondii?

Answer 2

All mammals including humans or birds;

• Pigs
• Goats
• Sheep
• Warthog
• Dog
• Cat

Question 3

What is the site of reproduction in felids for toxoplasma gondii?

Answer 3

Shizonts and gamonts are found in the small intestines.

Question 4

What is the site of reproduction in intermediate hosts of Toxoplasma gondii?

Answer 4

Tachyzoites and Bradyzoites are found in extra-intestinal tissue including lungs, muscle, brain and liver.

Question 5

The trophozoite form of Toxoplasma gondii, also known as the proliferative form, most commonly infect what in humans?

Answer 5

Most commonly the brain, retina, heart, and skeletal tissue.

Question 6

Describe the Trophozoites (Tachyzoites or bradyzoites) of Toxoplasma gondii

Answer 6

crescent-shaped and approximately 4-8 μm long and 2-4μm wide.

Question 7

How are cats most commonly infected with Toxoplasma gondii?

Answer 7

Through eating mice or birds (Bradyzoites)

Question 8

What happens after cats ingest Toxoplasma gondii cysts?

Answer 8

cysts are digested in the cat’s stomach and in the intestinal epithelium the liberated trophozoites undergo a cycle of schizogonous and gametogonous development culminating in the production of oocysts after 3-10 days.

Question 9

What are the 4 clinical patterns of Toxoplasmosis?

Answer 9

• The acquired disease
• The acquired disease in immunocompromised patients
• The congenital infection
• The ocular disease

Question 10

What are two ways to acquire Toxoplasma gondii infection?

Answer 10

-ingestion of infective oocysts
-ingestion of cysts in undercooked meat.
(Most are asymptomatic.)

Question 11

What is the most common clinical manifestation in symptomatic patients infected with Toxoplasma gondii?

Answer 11

Lyphoadenopathy

Question 12

What occurs in patients who have been previously infected with Toxoplasma gondii?

Answer 12

Lifelong immunity and positive IgG

Question 13

What symptoms do healthy people with infected with Toxoplasma gondii exhibit?

Answer 13

Asymptomatic

Question 14

How do the Tachyzoites of Toxoplasma gondii usually enter into cats?

Answer 14

raw milk

Question 15

How is Toxoplasma gondii transmitted?

Answer 15

• Eating undercooked meat (bradyzoites)
• Cat feces (oocytes)
• Drinking raw milk (tachyzoites)
• Vertical transmission from mother to child

Question 16

Describe the life cycle of Toxoplasma gondii

Answer 16

• Cats become infected with bradyzoites (rodent meat) or tachyzoites (raw milk).
• Reproduction to oocyst after 3-10 days.
• Unsporulated oocysts are shed for 1-3 weeks.
• Sporulate after 2-5 days (oocysts can last > 1 yr in environment
• Humans ingest sporulated oocysts, raw milk, undercooked meat
• invade adjacent cells - retina, brain, heart, and skeletal tissues.
• Infection can persist indefinitely

Question 17

How would one directly diagnose Toxoplasma gondii

Answer 17

Tissue biopsy

Question 18

Tachyzoites of Toxoplasma gondii are transported around the body in what?

Answer 18

Leucocytes

Question 19

What do you do for a negative IgG maternal test?

Answer 19

retest for IgM monthly

Question 20

What do you do for a positive IgG maternal test?

Answer 20

Rule out recent or active infection

Question 21

What do you do for a positive IgM maternal test?

Answer 21

Follow up infant and treat prophylactically

Question 22

What would you give in order to prevent vertical transmission of infants whose mothers become IgM postive during pregnancy?

Answer 22

Spiramycin

prophylactic for IgG(-) or IgM(+)

Question 23

What occurs with the rate of infection of vertical transmission depending upon trimester of pregnancy?

Answer 23

Increases depending upon which trimester infection occurs. (e.g. first tri = rate of infection is low during 1st trimester, but severity is high vs. rate of transmission is high 3rd trimester but severity is low since fetus builds immunity)

Question 24

What are some severe vertical transmission outcomes of toxoplamsa gondii infection in children?

Answer 24

-Chorioretinitis
-Hydrocephalus (obstruction of 3rd ventricle - bradyzoites in periventricular area of brain)
Chronic outcomes: Cognitive skills, visual impairment.

Question 25

Who is most at risk for developing toxoplasma gondii infection?

Answer 25

• People who eat undercooked meat.. esp lamb, goat or pork
• Cat owners
• Abattoir workers, butchers
• Veterinarians
• Children who eat soil or people who eat unwashed vegetables