Toxoplasma Gondii Flashcards
What is the definitive hosts of Toxoplasma Gondii?
Domestic cats
What are the intermediate hosts for Toxoplasma gondii?
All mammals including humans or birds;
- Pigs
- Goats
- Sheep
- Warthog
- Dog
- Cat
What is the site of reproduction in felids for toxoplasma gondii?
Shizonts and gamonts are found in the small intestines.
What is the site of reproduction in intermediate hosts of Toxoplasma gondii?
Tachyzoites and Bradyzoites are found in extra-intestinal tissue including lungs, muscle, brain and liver.
The trophozoite form of Toxoplasma gondii, also known as the proliferative form, most commonly infect what in humans?
Most commonly the brain, retina, heart, and skeletal tissue.
Describe the Trophozoites (Tachyzoites or bradyzoites) of Toxoplasma gondii
crescent-shaped and approximately 4-8 μm long and 2-4μm wide.
How are cats most commonly infected with Toxoplasma gondii?
Through eating mice or birds (Bradyzoites)
What happens after cats ingest Toxoplasma gondii cysts?
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.
What are the 4 clinical patterns of Toxoplasmosis?
- The acquired disease
- The acquired disease in immunocompromised patients
- The congenital infection
- The ocular disease
What are two ways to acquire Toxoplasma gondii infection?
-ingestion of infective oocysts
-ingestion of cysts in undercooked meat.
(Most are asymptomatic.)
What is the most common clinical manifestation in symptomatic patients infected with Toxoplasma gondii?
Lyphoadenopathy
What occurs in patients who have been previously infected with Toxoplasma gondii?
Lifelong immunity and positive IgG
What symptoms do healthy people with infected with Toxoplasma gondii exhibit?
Asymptomatic
How do the Tachyzoites of Toxoplasma gondii usually enter into cats?
raw milk
How is Toxoplasma gondii transmitted?
- Eating undercooked meat (bradyzoites)
- Cat feces (oocytes)
- Drinking raw milk (tachyzoites)
- Vertical transmission from mother to child
Describe the life cycle of Toxoplasma gondii
- 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
How would one directly diagnose Toxoplasma gondii
Tissue biopsy
Tachyzoites of Toxoplasma gondii are transported around the body in what?
Leucocytes
What do you do for a negative IgG maternal test?
retest for IgM monthly
What do you do for a positive IgG maternal test?
Rule out recent or active infection
What do you do for a positive IgM maternal test?
Follow up infant and treat prophylactically
What would you give in order to prevent vertical transmission of infants whose mothers become IgM postive during pregnancy?
Spiramycin
prophylactic for IgG(-) or IgM(+)
What occurs with the rate of infection of vertical transmission depending upon trimester of pregnancy?
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)
What are some severe vertical transmission outcomes of toxoplamsa gondii infection in children?
-Chorioretinitis
-Hydrocephalus (obstruction of 3rd ventricle - bradyzoites in periventricular area of brain)
Chronic outcomes: Cognitive skills, visual impairment.
Who is most at risk for developing toxoplasma gondii infection?
- 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
