Lecture 71 - Leishmaniasis, Toxoplasmosis, and Trypanosomiasis Flashcards
toxoplasma Gondii
- what kind of parasite is it?
- what is the definitive host?
-
Single celled protozoa
Cats are the definitive host
what are the forms of the Toxoplamsma Gondii?
- which are infective?
- which are diagnositic?
- describe the transmission?
Oocysts — infective form which is excreted in feces; fecal oral transmission; contaminated soil, vegetables, water, cat litter
Tissue Cysts – infective form which forms intracellularly in muscle and brain. Can be acquired from eating undercooked pork, lamb
Tachyzoites – the diagnostic stage–localized in brain and muscle tissue. Develop into tissue cyst bradyzoites. Can be transmitted transplacentally, blood tranfusions
What are the different disease forms of Toxoplasmosis
Acute Acquired Toxoplasmosis (tachyzoites)
chronic toxoplasmosis – (Bradyzoites)
Reactivated infections
Congenital Toxoplasmosis
Ocular Toxoplasmosis
Compare acute vs chronic toxoplasmosis
Acute – Tachyzoites infection
Usually subclinical – asymptomatic
may present with LAD, myalgias
Symptoms more common in immunocompromised
Disease is contained by Th1 response; leads to chronic cystic state
Chronic state – Bradyzoites:
Asymptomatic, lifelong infection
Cysts form in brain and neural tissue
source of reactivation
Congential Toxoplasmosis
- when would a child become infected?
- -what are the outcomes of severe infection?
- -outcomes for most infants?
Child infected if the mother becomes infected during gestation
Severe infection – miscarriage, neurological disease, ocular disease, generalized illness (HSM, LAD, Fever)
most – asymptomatic at birth but can have manifestations of occular or cerebral disease later in life
Occular Toxoplasmosis
- peak age of incidence
- symptoms and manifesations
Peak age of incidce – 20s, 30s from post acute or reactivated disease
Focal necrotizing retinitis; granulomatous inflammation, blurred vision.
Focal scarring can lead to permanent vision loss
Other manifestations of toxoplasmosis, for example in the immunocompromised
The disease can remain latent.
Tropism for brain and muscle tissue
Can manifest as cerebral disease, such as encephalaitis
Some association with schizophrenia
Diagnosis of Toxoplasmosis:
- Serologic: acute, chronic inactive, immunodeficient active
- what do you do for cerebral toxoplasmosis?
Serologic Profiles;
Acute – IgM + rising IgG
Chronic inactive – no IgM, + IgG
immunodef active – no IgM, +IgG
Other: Cerebral toxoplasmosis
- Imaging, brain bx
Treatment of Toxoplasmosis:
what is the treatment regimen for toxo during pregnancy
Regimen: Pyrimethamine + Sulfadiazine
(Leukovorin is always given with pyrimethamine)
Pregnancy:
Spiramycine
If Fetus infected:
terminate pregnancy or treat with Pyrimethamine + Sulfadiazine + leucovorin
Prevention of toxoplasmosis
Focus on women of child-bearing age and immunocompromised persons
Proper handling of cat liter
Wash hands when handling meat
Chagas Disease -- what is the bug? what is the vector? what is the technical term for the infection? Where does it most commonly occur?
Bug: Trypanosoma Cruzi
Vector: Triatomine bugs
Name: American Trypanosomiasis
Epi: Mostly in Latin America. Major cause of cardiac disease and mortality
Most cases in the US are from infected immigrant populations
Describe the lifecycle of the Trypanosoma cruiz? How does it infected humans ?
The parasite resides in the Gut of the Triatomine vector
Bug takes a blood meal, and defecates out Trypomastigotes on human hosts
Auto-innoculation; rub the feces in eye or wound. Trypomastigoes enters muscle, cardiac or smooth muscle
Differentiates into Amastigotes
Replication leading to rupture of the cell and differentiates back to trypomastigoes
Spreads throughout the blood stream.
Taken up in another blood meal
How is trypanosoma transmitted ?
Vector Born –
Trans placental
Ingestion – rare (eg bugs on fruit)
Describe the acute vs chronic phases of trypanosomiasis?
- symptoms and manifestations
Acute: 1-2 months following transmission
Fever, mononucleosis
High levels of parasitemia
Symptomatic < 1%
May lead to acute myocarditis; meningoencephalalitis
Chronic –
Few parasites in the blood
descrtruction of cardiac myocytes; replaced by fibrotic tissue; leading to CHF, arrythmias, complete heart block and thrombo-embolism
the disease is life long and may reactive when immunosuppressed
What are the manifestations of trypanosomiasis?
- cardiac
- Gi
acute myocarditis
CHF, arrhythmias, complete heart block, thromboembolism
Gi - mega colon, mega esophagus
