T' cruzi facts lifecycle continued

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T. cruzi facts / life-cycle continued

• T. cruzi is transmitted via the feces of the
  triatomid bug which is introduced when the insect
  bites (he likes to defacate while he feeds
  nobody has asked him why). The DH rubs the
  painful bite thereby rubbing the bug feces (if
  present) into the wound. Bites are most common
  around the facial area, hence the name kissing
  bug. Triatomid feces can also be introduced in
  an already present wound and into the conjunctiva
  of the eye. Transmission also occurs via blood
  transfusion and perinatally. There are 2 disease
  causing troph stages of T. cruzi a) the
  tryp(an)omastigote which is found in blood, and
  the b) amastigote (leishmanial form) which is
  present in advanced chronic cases, and is found
  in visceral connective tissues
  reticuloendothelial, cardiac, brain. Amastigotes
  divide asexually intracellularly (often in
  macrophages) to become trypomastigotes.

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• T. cruzi
• disease (South) American trypanosomiasis,
  Chagas
• intermediate host triatomid or reduviid bug
• usually bites on the face also called
  kissing bug
• definitive host humans
• house pets, rodents, wild animals

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T. cruzi life-cycle
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Focus on pathogens Trypanosomes

• T. cruzi Epidemiology
• found in southern U.S. - C. America - all of S.
  America.
• 16-18 million currently infected, half of these
  in Brazil.
• 50 million at risk 50,000 annual deaths
• most cases are children
• US cases are rarely endemic? Travel? Imports?
• many years (?) following the initial acute
  symptoms, 10-30 of patients develop the advanced
  chronic symptoms latency?
• much more treatable (or treated?) than T. brucei
  lower mortality. This is at least true of the
  acute phase.

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Focus on pathogens Trypanosomes

• T. cruzi pathology / clinical symptoms
• swollen knot (chagoma) at site of bug bite /
  feces introduction
• painless edema of perioccular tissues
• recurring fever
• lymphodenopathy
• edema of lower extremities
• advanced chronic symptoms
• visceral / connective tissue involvement (unique
  to Chagas)
• reticuloendothelial intra-macrophage
  amastigotes
• visceral megaesophagus, megacolon
• cardiac muscle cardiac dilation, multiple
  carditis ? failure
• brain tissue meningoencephalitis ? coma ? death

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Focus on pathogens Trypanosomes

• T. cruzi Laboratory diagnosis of trophs
• Tryp(an)omastigote
• sample blood
• C-shaped troph with classic trypanosome morph
  (see
• description on T. brucei laboratory
  diagnosis slide?)
• 15-20uM long 1-3uM wide
• Amastigote
• sample blood, biopsy
• will be seen intracelluarly intra-macrophage
  parasites
• round-oval, 2-4uM in size
• lacks a prominent flagellum

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T. cruzi trypomastigotes
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T. cruzi amastigotes