Lecture 03 - American Trypanosomes Flashcards
What disease is caused by american trypanosomes
Chagas disease
What species of Trypanosomiasis is the american trypanosome
T. cruzi
Where is chagas disease endemic
21 countries in contenetal latin america
Where is T. cruzi highest prevalence
Bolivia, Argentina, Paraguay, Ecuador, El Salvador, and Guatemala
How is T. cruzi transmitte
triatomine insects or kissing bugs
ingestion of contaminated food/drink
mother-child
blood transfusion
organ transplantation
laboratory accidents
How does the triatomine insect get infected with T. cruzi
By sucking blood from humans or animals that have circulating trypomastigotes
How does the triatomine insect infect humans
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
How does infection occur
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
Where do kissing bugs typically bite
the face
What is unique about the kissing bug
when it bites it injects its saliva which has anesthetic properties
What is an amastigote
a protest cell that does not have a visible external flagella or cilia, intracellular replication phase
What are promastigotes
elongated or fusiform with flagella extended forward
What are trypomastigotes
flagellum runs entire length from posterior, found in the blood stream
What are epimastigotes
elongated with anterior flagella
When is the acute phase of chagas disease
8-12 weeks after transmission
When is the chronic phase of chagas disease
in the absense of successful antitrypanosomal therapy usually 8-12 weeks after onset of infection and lasts for the patients life
What is the presentation of acute chagas disease
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
What is the presentation of chronic chagas disease
heart rhythm disturbances, HF, gastrointestinal
How is chagas disease diagnosed
serology, circulating parasites, tissue biopsies, xenodiagnosis, PCR
How does the CDC test for chagas disease
two different serologic tests, if results are discordant an immunofluoresence assay is used as a tie breaker
What is the treatment for chagas disease
Antitrypanosomal agent
- benznidazole
- nifurtimox
How to prevent chagas disease
avoid habitation in buildings vulnerable to infestation
insecticide bed nets
screening blood donors from endemic area
