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Trypanosomiasis

Trypanosomiasis. Ziad Elnasser, MD, Ph.D. Parasitology. Trypanosoma brucei with 3 subspecies: gambiense, rhodesiense and brucei identified by their biology, zymodemes and DNA types.

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Trypanosomiasis

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  1. Trypanosomiasis Ziad Elnasser, MD, Ph.D

  2. Parasitology • Trypanosoma brucei with 3 subspecies: • gambiense, rhodesiense and brucei identified by their biology, zymodemes and DNA types. • Life cycle: Glossina fly (tse tse), epimastigote form, trypomastigote form, saliva, VSG development, blood, division, morphology change, antigenic variation, glossina fly.

  3. African trypanosomiasis (Sleeping sickness) • Lethal meningoencephalitis. • West african or east african types, Nagana in cattle. • Epidemiology: Africa 10,000 – 20,000/y. • Humans are reservoirs in gambian while the antelop in Rhodesian.

  4. pathogenesis • Skin chancre. • Blood and LNs, IgM and C, antigenic variation. • CNS, and heart small vessles involvement Hg, demyelinating panencephalitis. • Poly clonal B cell activation→IgM, heterophile Abs, anti DNA, and RF, cell destruction, immune complexes, anemia and vasculitis.

  5. Clinical Aspects • Chancre. • Fever, tender LNs, rash, headache, and impaired mentation. • Heart failure, convulsions, coma and death may follow. • Attention waves, tremors, sphinctor control is lost, seizures, transient bouts of paralysis, and final coma.

  6. Diagnosis • Lymph nodes aspirate, Blood, CSF→ look for trypomastigotes, if not centrifuge and examine buffy coat. • Animal inoculation. • Ab detection IgM type, simple card agglutination. • DNA probes.

  7. Treatment • LP must be done first to use agents crosses the blood – brain barrier. • Melarsoprol B is the best. • Eflornithin (ornithine dexarboxylase inhibitor) alone or with Suramine. • Less toxic than Mel B, varialbly effective for T. rhodesiense. • Suramine, Pentamidine, or eflornithine can be used if the CNS is not involoved.

  8. Prevention • Tse tse fly control measures. • Insecticides. • Deforstation. • Sterile males. • Eradication of reservoirs. • Vaccine difficulties. • Personal protection from flies.

  9. American Trypanosomiasis • Trypanosoma cruzi and reduvid bug. • No extracellular multiplication (amastigote) • Trypomastigote → amastigote → trypomastigote → epimastigote in bug. • Many serotypes. • C or U shape, large kinetoplast, narrow undulating membrane.

  10. Chagas disease • Leading cause of heart disease in s. America. • Reduvid bug bites at night. • Kissing bug or assassin bug. • Rats, cats, dogs, opossums, and armadillos act as reservoirs. • Blood transfusion and transplantation.

  11. Pathogenesis • Local chancre or Chagoma. • Febrile illness one to 3 months. • Any nucleated cell in the body can be infected, heart, CNS, skeletal muscles. • Penetrin on trypomastigote binds to fibronectin transforms to amastigote, pseudocyst development. • Humoral and CMI destroys the organism. • Parasite antigen binds to other tissues resulting more injury, heart damage.

  12. Clinical Aspects • Nodular erythematous chagoma. • Romana’s sign if entry is through the eye. • Fever, LNs ↑, hepatospleenomegally. • Meningeal irritation, tachycardia, ECG changes. • Myocardium and the induction system. • Mega colon and megaeosophagus.

  13. Diagnosis • Trypomastigote in the peripheral blood. • Xenodiagnosis. • Culture or animal inoculation. • Chronic disease difficult to diagnose. • Immunodiagnosis. • PCR .

  14. Treatment and prevention • Nitrofuramox. • Benznidazole. • Allopurinol. • Insecticides, fumagatives. • Testing blood donors. • No vaccines.

  15. Filarial Worms • Wuchereria bancrofti • Brugia malayi. • Loa loa • Onchocerca volvolus.

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