Sem 2: Kinetoplastids (Trypanosoma) Flashcards
Kinetoplastid=
organelle containing tightly-packed mitochondrial DNA
What’s the vector of Trypanosoma cruzi?
kissing bugs
Explain the life cycle (2 stages) of Trypanosoma cruzi:
VECTOR STAGE:
a. kissing bug takes a blood meal, ingests trypomastigotes
b. trypomastigotes differentiate into epimastigotes, which replicate in the midgut
c. epimastigotes differentiate into trypomastigotes in the hindgut and are excreted in feces
HUMAN STAGE
a. trypomastigotes enter through bite wound etc
b. trypomastigotes invade nucleated cells
c. trypomastigotes differentiate into amastigotes and replicate (binary fission inside cell during human stage)
d. intracellular amastigotes transform into trypomastigotes & host cell ruptures
e. trypomastigotes enter the blood stream, kissing bug takes a blood meal (vector stage restarts)
T/F
Trypanosoma cruzi can only be contracted from kissing bugs as a vector
false
Humans can also get this parasite via food, organ transplants, blood transfusions
Where are kissing bugs found?
southern US, Mexico, Central/ south American
Typically called American trypanosomas
Why are Triatomas called kissing bugs?
They usually bite around the mouth and eyes- will feed on humans, dogs, raccoons, some other rodents
T/F
Trypanosoma is transmitted through the saliva of the kissing bug when it bites
False
The parasite is transmitted through the insect feces, not the saliva
Metacyclogenesis=
the differentiation of the epimastigote in the hind gut into a metacyclic trypomastigote
Where is the metacyclic trypomastigote found?
In the feces of the bug (it’s the infecting form). We don’t have any of these in our blood
In the epimastigote, the nucleus is higher and smaller than in the trypomastigote. The yellow thing (??) also enters the trypomastigote, while it’s ___of the epimastigote
outside
Explain acute chagas disease
- symptoms arise 1-2 weeks after infection
- usually asymptomatic
- parasites circulate in the blood
- lasts a few weeks-months
Explain chronic chagas disease
- few or no parasites found in blood
- can be a lifelong infection & can be asymptomatic the whole time
- 20-30% develop severe symptoms (dilated heart, rhythm abnormalities, dilated esophagus or colon)
Chagas disease is very difficult to detect, especially if the patient is _____
immunocompromised
In African trypanosomiasis, the tsetse fly is the ___ host and cattle are ___.
There is no sexual rep. in this parasite, only ___ ____
definitive
reservoirs
binary fission
Explain differences between the following
- T.b. gambiense
- T.b. rhodesiense
- T.b. brucei
T.b. gambiense
- western and central africa
- slow progressing (chronic)
- domestic animals
T.b. rhodesiense
- eastern and southern africa
- fast progressing (acute)
- wild animals
T.b. brucei
- animal trypanosomiasis
- susceptible to apolipoprotein A1 (we have this protein in our blood, so we cannot get T.b. brucei
Acute African Sleeping sickness is caused by ____
Chronic african sleeping sickness is caused by _____
T.b. rhodesiense = acute
T.b. gambiense= chronic
The potentially fatal stage of african sleeping sickness is the __________ stage
- parasite is in the ____ ____ ____
meningoencephalitis stage
central nervous system
- diagnosed by looking at spinal fluid
no treatment :(
What are variant surface glycoproteins (VSGs)?
a glycoprotein surface coat (glycans attached to proteins)
- occurs in human stage in the bloodstream
Offers protection via density to invariant surface proteins
Can see a VSG layer of the parasite covering the entire cell
T/F
VSGs do not produce an immune response
FALSE
highly immunogenic
- antibodies kill trypanosomes 5-7 days post infection
In Leishmania, the sandfly is the ___, and humans are ____ hosts
vector (definitive host)
humans= reservoir
Explain the life cycle of Leishmania sp.
HUMAN STAGE
a. sandfly takes a bloodmeal, injects promastigotes into skin
b. promastigotes are phagocytized by macrophages
c. promastigotes transform into amastigotes
d. amastigotes multiply in cells of various tissues & infect other cells
SANDFLY STAGE
a. takes a bloodmeal, ingests macrophages infected with amastigotes
b. amastigotes transform into promastigote stage in the gut
c. promastigotes divide in the gut and migrate to proboscis
d. sandlfy bites human and injects promastigote into skin
What’s the most common form of leishmaniasis?
Give the 2 other forms
cutaneous
- skin sores at site of bite
Can also be visceral (lesions on internal organs) or mucosal (on nose/ mouth/ throat)
