Biology,, Chagas' Disease: : Biology Chagas' Disease

 
 
Biology,, Chagas' Disease: : Biology Chagas' Disease
Chagas’ Disease: Biology,
Immunology & Clinical Aspects




 Infectious agent: Trypanosoma cruzi



       Parasitology MIMM-413
         (Winter term 2004)
Biology,, Chagas' Disease: : Biology Chagas' Disease
Discovery & Distribution



     Carlos Chagas, 1909
Observed cone-nosed bugs with
   hindguts swarming with
      trypanosomes of
      epimastigote type

   1916, he demonstrated that
 acute, febrile disease, common
in children throughout the range
of cone-nosed bugs, was always
       accompanied by the
          trypanosome.
Epidemiology



* Central and South America
  (case in southern USA)

* In poor country sites and suburbs
   (Vector still found in rich suburbs)

* Reservoirs: Domestic animals, Rodents
              Bats, Armadillo
T. Cruzi infection in Human
Trypanosoma cruzi Morphology


                T. brucei (african) T. cruzi (american)
Form               Stumpy-slender          Slender

Posterior end       rond-pointed           pointed
                                                             Trypomastigote
                                                             (Question Mark Shape)
Kinetoplast       Small, terminal   Large, sub-terminal

Undulating     5-6 undulations      2- 3       undulations
        Membrane


Flagella               Long                  Short

Amastigote         No        Yes
Form                   When Intracellular
……………………………………………………………………………
Transmission Salivaria Stercoraria
Vector: Reduviid bugs (Triatoma & Rhodnius)




                         a.k.a. Kissing bug
Entry of T. cruzi in fibroblast




                     QuickTime™ et un décompresseur
                      GIF sont requis pour visualiser
                                 cette image.




*** In phagocytic cells (i.e. Macrophages), entry is receptor-mediated
Clinical Manisfestations
Incubation: 20 days

Acute form:      Oedema

                 Anemia

                 Local Inflammation
                 (known as Chagoma)

                 Adenopathies         QuickTime™ et un décompresseur
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                 Fever (40 C)

                 Hepatosplenomegaly

                 Myocardite
*** Death possible in 3-4 weeks
    (Most common among children
     under 5 years old)
Chronic form and Severe Pathologies

Development: 10 years and more (mainly in adults)


Pathologies:   Ventricular hypertrophy

               Global cardiac fealure
               (70% cardiac death in young adults
                of endemic area)

               Megaesophagus and Megacolon
               (Fatal when patient no longer swallow
                or accumulate feces)

               Flabbiness of organs
T. cruzi pseudocyst in cardiac muscle




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T. cruzi pseudocyst in cardiac muscle




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Chagas’ Cardiopathy
   Marked Reduction of Nerve Fiber


Normal Heart         T. cruzi-infected
Pseudocyst of Trypanosoma cruzi in brain tissue




                  QuickTime™ et un décompresseur
                   GIF sont requis pour visualiser
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Stages of Chagasic Esophagopathy



Normal       Hypertrophy and Dilatation




    Megaesophagus
Diagnostic
Acute Phase: Search for parasite in blood
              * Thick blood slide
              * Hemoculture,
              * Culture in NNN media
              * Inoculation to mouse

               Xenodiagnostic
               (use of uninfected bugs)

Chronic Phase: Serology
               (immunofluorescence)

               PCR
                (Molecular diagnostic)

               Histology
                (Immunofluorescence)
Treatment
Chemotherapeutic treatment

Acute phase:

     Lampit or Radanil

     Poor response to treatment
     (Only kill extracellular parasite)

     Possible use of Amphotericin B
      (can target intracellular parasites)

Chronic phase:

     Only if symptomatic
Prevention


Bugs control with insecticide

Better house using modern materials

Brazil is almost free of T. cruzi
(Aggressive programof prevention and sanitation)


No vaccine available
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