TOXOPLASMA

Question 1

What kind of pathogen is Toxoplasma?

Answer 1

Intracellular parasite protozoan

Question 2

What is a strain of Toxoplasma?

Answer 2

Toxoplasma gondii

Question 3

What is the epidemiology of Toxoplasma gondii?

Answer 3

-Infects a lot of the world’s population without causing significant disease
-Wide spectrum in humans
80-90% asymptomatic

Question 4

How is Toxoplasma gondii transmitted?

Answer 4

Principle stage will be in cats and cat prey
and can be transmitted by changing a cat’s litterbox

Question 5

What is the pathogenesis of Toxoplasma gondii?

Answer 5

Starts in cats/cat prey
-Host ingests cysts/eggs, these will invade the gut
-Parasite will be resistant to proteases (enzymes) and can spread into other tissues like the CNS and eyes

-Can remain as cysts for years but when activated will replicate and invade adjoining cells: causing necrosis with acute inflammation

Question 6

Who is at greater risk for Toxoplasma gondii symptomatic infections?

Answer 6

-Fetuses in pregnant mothers
-Newborns
-Immunocompromised

Question 7

How does a Toxoplasma gondii infection present?

Answer 7

Acute toxoplasmosis in immunosuppressed patients:
-cervical lymphadenopathy (swelling of lymph nodes in neck)
-CNS effects: seizure, ataxia (involuntary movement), altered mental status, focal neuro deficits
-fever, malaise, night sweats, myalgias, sore throat
-retropharyngeal and abdominal mesenteric swelling
-Retinochoroiditis (ocular disease)
-Myocarditis/pneumonitis

CONGENITAL DEFECTS IN FETUS: infection of mother when pregnant can spread to fetus in utero or delivery and cause severe infant toxoplasmosis:
-encephelomyelitis
-abortion
-neonatal death
-survivors will have severe deficits (microencephaly, seizures, visual defects, mental development delays)
*the later the pregnancy, the more severe risks

Question 8

How can a Toxoplasma gondii infection be diagnosed?

Answer 8

-CT/MRI
-Hitopathology: biopsy
-Serology (blood): IgG and IgM (10-15% will be positive in the US even if asymptomatic)
-PCR

Question 9

How can Toxoplasma gondii be treated?

Answer 9

-Pyrimethamine, sulfadiazine, leucovorin
-Bactrim, atovaquone, azithromycin

-Prophylaxis (preventative) treatment for high risk exposure: Bactrim or Pyrimethamine, clindamycin, leucovorin