Trypanosoma Flashcards
What are the African trypanosome species?
Trypanosoma brucei gambiense (West Africa) & Trypanosoma brucei rhodesiense (East Africa).
RARELY Trypanosoma brucei brucei (normally does not affect humans)
What is the American trypanosome species?
Trypanosoma cruzi
What is the common name for African Trypanosome disease and where is it found?
sleeping sickness. not found in deserts but in the surrounding areas in Africa
What is the vector for the African Trypanosomes?
tsetse fly, genus Glossina
how are the two species differentiated?
they are morphologically different
What does Trypanosoma brucei brucei do?
- African ruminants as host
- causing nagana, a type of sleeping sickness in animals
- reduces growth rate, milk productivity & strength, leading to eventual death
- very difficult for farmers
How are the equine and camel trypanosomes different?
T equinim, T equiperdum, and T evansi are transferred by blood contact during copulation or by other biting insects that probe animals for blood (ex horse flies).
more widespread disease bc outside tsetse fly range
What are the preferred hosts for each trypanosoma species?
T brucei gambiense: prefer humans but also infect pigs & other animals
T brucei rhodesiense: prefer wild animals but will also infect humans
How else can the parasite be transferred?
- across the placenta
- blood transfusion
- sexual contact (rare)
- lab accidents
Which species causes the chronic condition?
Tb gambiense (central & western Africa). can take time for symptoms to emerge
Which species causes the acute condition?
Tb rhodesiense (southern & eastern Africa). emerges in a few weeks, develops quickly and is more virulent
How does Trypanosoma evade the host immune system and how does this work?
Antigen Variation
- uses variant surface glycoproteins (VSGs)
- covers itself with VSGs
- when attacked, changes VSGs
- has over 1000 vsg genes
What is the pathogenicity of Tb gambiense?
invades the central nervous system
causes apathy, mental dullness, tremor of hands, lethargic tongue. followed by convulsions and paralysis
followed by coma and death
What is the pathogenicity of Tb rhodesiense?
does not attack the nervous system
causes rapid death after weight loss and heart involvement
winterbottom’s sign= swelling of lymph nodes along the back of neck
How is sleeping sickness diagnosed?
detection of trypomastigote (only found in humans) from lymph node, blood, bone marrow or cerebral fluid. observe motile parasites, then fix and use giemsa stain
How is sleeping sickness treated?
Pentamidine (West) & suramin (East) treat the hemolymphatic stages
melarsoprol treats the late disease with central nervous system involvement
Where does Tb gambiense deposit its larvae?
moist areas along rivers. a bit easier to control
Where does Tb rhodesiense & brucei deposit their larvae?
in dry soil. more difficult to control
How can both trypanosoma brucei be controlled?
chemical spraying, elimination of wild game, selectively breeding cattle
What is the name of the disease caused by Trypanosoma cruzi?
Chagas disease
What is the vector species of Trypanosoma cruzi?
triatomine bugs (aka kissing bug) belonging to Triatoma, Rhodinius and Panstrongylus
How else can chagas disease be transmitted?
- blood transfusions
- organ transplants
- transplacentally
- lab accidents
How does the triatomine bug transfer the parasite?
takes a blood meal, then defecates. parasite is carried in feces
different species defecate at different times and can have different chances of transmitting the disease
How are animal affected?
also get bit, but often do not get the disease
What is the pathogenicity of Trypanosoma cruzi?
manifests in hollow organs and causes cell death because of parasite replication. may infect individuals for life
heart is often infected and can cause serious problems if blood vessels rupture
What is Romana’s sign?
a marker of acute chagas disease. swelling of the eyelid due to feces getting rubbed into the eyes
What are some symptoms of Chagas disease?
early: local swelling
late: heart disease, malformation of intestines. fatal
What occurs in the chronic phase?
immunity to re-infection but parasites still present and cause problems including cardiomyopathy, megaesophagus, megacolon. can also be asymptomatic
How can Chagas disease be diagnosed?
identification of amastigotes or trypomastigotesvia blood smears (thick & thin using giemsa. common) or biopsies (less common)
How is Chagas disease controlled?
no vaccine
insecticides & improving house sanitation. paint house with insecticides
mosquito nets
testing blood before transfusion
