tsetse and trypanosome Flashcards
Glossina species (tsetse flies)
around 50 species
obligate blood feeders - no other source of nutrition
giver birth to live young and have milk glands
highly sensitive to insecticide
African trypanosomes
3-4 species with high disease relevance
cause sleeping sickness in humans (T.b. rhodiense and t.b gambiense only)
How do trypanosomes survive in blood?
Antigenic variation - in slender forms not stumpy forms
stumpies only produced at peak of parasitemia
pleomorphic in blood
VSG coat - good at clearing antibodies
Trypanosome journey in fly
blood goes into lumen
trypomastigotes differentiate into procyclic trypomastigotes, cross peritrophic matrix barrier and establish gut infection
Epimastigotes colonize the proventriculus organ in anterior midgut
epimastigotes differentiate into metacyclic trypomastigotes in salivary glands where transmitted to host
cycle duration - 15 - 30 days
Challenges fro tryp development in tsetse
mid gut survival
peritrophic matrix crossing
migration to salivary gland
transmission to mammal
Why are tsetse flies refractory to tryp infection in the wild?
Age - older flies less likely to get infection
sex - males get infected more easily than females
species
Factors influencing establishment of tryp in tsetse
- Blood factors - Sialic acids- enhance parasite survival
procyclic tryps sensitive to complement in midgut - Tsetse immune sytem - EP proteins - only found in tsetse- protect from parasite
- Bacteriome - contains wiggleworthia and sodalis
wigglesworthia makes folic acid essential for fly and tryp.
Trp adaption to tsetse midgut
tryps hide in ectoperitrophic space
l- proline - main carbon source for procyclic tryps
tryps breach the PM to infect ES
parasites dont produce chitinase to break PM - wait until PM collapses
not all tryps live in midgut
T. vivax - lives in proboscis
T. brucei- lives in salivary glands
all transmitted by saliva
