Lecture 03 - American Trypanosomes Flashcards

1
Q

What disease is caused by american trypanosomes

A

Chagas disease

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2
Q

What species of Trypanosomiasis is the american trypanosome

A

T. cruzi

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3
Q

Where is chagas disease endemic

A

21 countries in contenetal latin america

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4
Q

Where is T. cruzi highest prevalence

A

Bolivia, Argentina, Paraguay, Ecuador, El Salvador, and Guatemala

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5
Q

How is T. cruzi transmitte

A

triatomine insects or kissing bugs
ingestion of contaminated food/drink
mother-child
blood transfusion
organ transplantation
laboratory accidents

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6
Q

How does the triatomine insect get infected with T. cruzi

A

By sucking blood from humans or animals that have circulating trypomastigotes

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7
Q

How does the triatomine insect infect humans

A

infective metacyclic trypomastigotes are discharged with feces at the time of the blood meal, this then enters the host via mucous membranes, conjunctiva or breaks in the skin

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8
Q

How does infection occur

A

the parasite enters cells and multiplies before differentiating into trypomastigotes forcing the cell to rupture, they then invade the local tissue or spread via circulation

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9
Q

Where do kissing bugs typically bite

A

the face

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10
Q

What is unique about the kissing bug

A

when it bites it injects its saliva which has anesthetic properties

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11
Q

What is an amastigote

A

a protest cell that does not have a visible external flagella or cilia, intracellular replication phase

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12
Q

What are promastigotes

A

elongated or fusiform with flagella extended forward

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13
Q

What are trypomastigotes

A

flagellum runs entire length from posterior, found in the blood stream

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14
Q

What are epimastigotes

A

elongated with anterior flagella

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15
Q

When is the acute phase of chagas disease

A

8-12 weeks after transmission

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16
Q

When is the chronic phase of chagas disease

A

in the absense of successful antitrypanosomal therapy usually 8-12 weeks after onset of infection and lasts for the patients life

17
Q

What is the presentation of acute chagas disease

A

inflammatory lesion at site of entry (called chagoma)
fever/chills
anorexia
malaise
edema of face and lower extremities
lymphadenopathy
hepatosplenomegaly
sometimes CNS involvment
acute myocarditis and arrhythmias

18
Q

What is the presentation of chronic chagas disease

A

heart rhythm disturbances, HF, gastrointestinal

19
Q

How is chagas disease diagnosed

A

serology, circulating parasites, tissue biopsies, xenodiagnosis, PCR

20
Q

How does the CDC test for chagas disease

A

two different serologic tests, if results are discordant an immunofluoresence assay is used as a tie breaker

21
Q

What is the treatment for chagas disease

A

Antitrypanosomal agent
- benznidazole
- nifurtimox

22
Q

How to prevent chagas disease

A

avoid habitation in buildings vulnerable to infestation
insecticide bed nets
screening blood donors from endemic area