Toxoplasmosis & Trichomonas Flashcards
How can you get toxoplasma infection?
Ingesting tissue cyst stage in infected, undercooked meat
Ingesting oocyst stage, which comes from cat feces, in contaminated water or food
Congenital infection
Organ transplant or blood transfusion
Once you ingest toxo, how does it spread and cause disease?
If you ingest bradyzoite from meat – acid in stomach liberates it, then penetrates mucosa of small intestine, multiplies in lamina propria, then spread through lymphatics and vasculature
If you ingest oocyte, they get liberated in duodenum, then penetrate mucosa of small intestine, etc
Why shouldn’t pregnant women change cat litter?
Because they can get infected with toxoplasmosis gondii & it can spread to the fetus
What is the clinical manifestation of Toxoplasma gondii in immunocompletent patients?
Most are asymptomatic
Can get a viral-like illness during primary infection: lymphadenitis, chorioretinitis (inflammation of uvea=middle layer of eye)
Rarely: myocarditis, polymyositis, encephalitis
What is the clinical manifestation of toxoplasma in those with impaired cell immunity?
Mononucleosis-like syndrome: cervical lymphadenopathy, flu-like symptoms, hepatosplenometaly, etc.
Overlap with mono due to EBV, CMV, lymphoma
Who can transmit toxoplasmosis during pregnancy?
Pregnant women who have negative serology tests
Rarely transmitted if mom is seropositive, bc the infection is now latent
What are the symptoms of congenital toxo infection?
Strabismus (cross eye), epilepsy, mental retardation, anemial, jaundice, rash, thrombocytopenia, encephalitis, microcephaly, sensorineural hearing loss, intracranial calcifications, hydrocephalus
Who can get chorioretinitis due to toxoplasmosis?
Congenital or acquired infections can cause it
Relapsing disease bc it is reactivation of latent infection
What are the symptoms of chorioretinitis? Why do you get these symptoms?
Reactivation –> bradyzoites transform to tachyzoites –> proliferate, cause acute chorioretinitis
Congenital patients get it around age 30
Acquared infections between 40-70 years old
Blurred vision, scotoma (partial alteration of field of vision), pain, photophobia, epiphora (tears overflow down face)
What is the clinical presentation of encephalitis due to toxo in HIV patients?
CD4 count <100
Focal CNS lesions: enhancement (which means that there’s necrosis, disturbance of BBB), edema, midline shift
Altered MS, seizures, weakness, neuropsych symptoms, stroke-like presentaiton
Rarely see chorioretinitis
How do you diagnose T. gondii?
**Serology
PCR & histology
Which medications can you use to treat toxo? What is their mechanism of action?
Inhibit folate synthesis in the parasite
Pyrimethamine
Sulfadiazine
What is the mechanism of action of pyrimethamine?
Inhibits folate pathway: dihydrofolic reductase inhibitor (trimethoprim also inhibits this enzyme)
SE include bone marrow suppression, thrombocytopenia, neutropenia, anemia
What should you co administer with the folate inhibitors?
Folinic acid: because our cells can use it but the parasite cells can’t
That way you get fewer side effects
What’s the mechanism of action of sulfadiazine? SE?
Inhibits dihydropteroate, which is an earlier step in folate synthesis
SE include hypersensitivity, Stevens Johnson
