Flashcards in Trypanosomes Deck (25)
Two species of Trypanosomes we need to know:
1. T. cruzi
2. T. brucei
Let's start with T. cruzi. Where do we find this guy?
This is also called: American Trypanosomiasis
Will T. cruzi be in the clean homes or the dirty ones?
Dirty ones. It's a/w with rural, poor housing w/ dirt walls
What 3 considerations should you make with dx of T. cruzi
1. Blood smear shows trypanosoms during active infection
2. Use serology during chronic infection
3. Cardiac biopsy shows trypanosoms in myocytes. (not often done)
What signs will you see in an acute (w/in 1-2 wks) infection of T. cruzi?
1. Romana’s sign (feces drips into your eye→ painless unilateral periorbital edema).
2. Chagoma: indurated lesion at site of parasite entry
3. Rarely causes acute myocarditis or meningoencephalitis mostly in infants and immunocompromised pts.
Will the smear be + in an acute T. cruzi infection?
Yes, as will culture and PCR
In the chronic form of the disease (4-8 wks post infection) will the smear still be +?
Nope, dx is done by serology (*2 different assays w/ 2 different antigens)
What's going on in the intermediate form of T. cruzi?
2 options here:
1. No sx (70-80% of pts)
2. Develop Chagas dz (20-30% of pts)
What are we going to see in Chagas Disease?
1. Dilated cardiomyopathy (often fatal). R-bundle branch block. Other structural/conduction heart problems. (80% of pts)
3. Megacolon: constipation, acute abdomen w/ perforation of colon
Tell me the 3 forms of T. cruzi?
Vector form: Epimastigote, metacyclic tryp.
Blood form: trypomastigote, classically “C” shaped.
Tissue form: amastigote.
What's the vector for T. cruzi?
1. Reduviid in the Family Triatomine aka “Kissing bug” (big bug bites in the night).
2. American vectors include raccoons, armadillos, skunks.
Other silly ways to get it: juices in endemic areas, contaminated blood donation.
What's the pathophys of T. cruzi
Feces deposited when bug bites around human’s mouth, typically. Goes into skin by itching. Tissue form, amastigote, tunnels into tissue and feeds on blood/lymph.
Is this guy, T. cruzi, motile? Discuss.
Yes, it's motile with base of flagella in close association with the kinetoplast. Kinetoplast contains DNA (similar to mitochondrial DNA in that it's minicircles)
What's the treatment for T. Cruzi?
No tx for chronic Chagas.
Moving on to T. brucei. Where does this dude live?
There are two kinds of T. brucei. They are:
(western vs eastern part of Africa respectively).
What type of infection will travelers get? Gambiense or Rhodesiense?
Travelers get Rhodesience > Gambiense (people get it on safaris--it has much higher parasitemia and can present as acute febrile illness)
How does the dx work for T. brucei?
Trypomastigotes seen on blood smear. CSF (LP) or lymph also used sometimes.
What's the main thing we're worried about with T. brucei?
African Sleeping Sickness (Human African Trypanosomiasis aka HAT)
1. Acute phase: may see chancre
2. Recurrent fevers (blood infection)
3. Cervical/axillary lymphadenopathy→ Winterbottom’s sign=posterior cervical adenopathy
4. Personality changes, ataxia, tremor, daytime somnolence, insomnia, coma (CNS infection)
What's a special cell you might see with a T. brucei infection?
Mott cells: large eosinophilic plasma cells that failed to release its IgM (has a ton of IgM in it)
Different forms of T. brucei?
1. Vector form: epimastigote, metacyclic tryp,
2. Blood form: Trypomastigote.
3. No tissue form: Stays extracellular.
Vector for T. brucei?
Tell me two things about the structure of T. brucei?
1. Has variable surface glycoprotein (VSG) coats that undergo constant antigenic variation → chronic infection.
2. Motile, w/ single flagella.
Tx for Gambiense?
Early gambiense: pentamidine
Late gambiense: eflornithine/nifurtimox