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African Sleeping Sickness

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African Sleeping Sickness. African Trypanosomaisis. http://phil.cdc.gov/phil/details.asp. History. Nagana : -Zulu “To be depressed” First described in the 14 th century Noticed by slave traders who would not buy slaves displaying symptoms Trypanosomes first detected in humansin 1902.

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African Sleeping Sickness

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  1. African Sleeping Sickness African Trypanosomaisis http://phil.cdc.gov/phil/details.asp

  2. History • Nagana: -Zulu “To be depressed” • First described in the 14th century • Noticed by slave traders who would not buy slaves displaying symptoms • Trypanosomes first detected in humansin1902. http://www.uoguelph.ca/~pwoo/animaltryp.jpg

  3. Worked in Ubombo, South Africa with wife Mary Discovered both trypanosome and transmission by tsetse fly in 1903 ‘trypanosome fever’ = ‘sleeping sickness’ Sir David Bruce

  4. Epidemiology • Bites of Tsetse flies, vertical, or mechanical transmission • Earliest epidemic took place between 1896 and 1906; estimated 800,000 died. • Major break outs in 1940’s and 1980’s; smaller epidemics from Senegal to Cameroon from 1920-1940’s. • Linked to droughts and political turmoil due to increase human-fly contact

  5. Glossina/Tsetse flies http://www.medicalecology.org/diseases/d_african_trypano.htm#sect5.3

  6. Human African Trypanosomiasis http://www.stanford.edu/class/humbio103/ParaSites2001/trypanosomiasis/trypanpo_files/image044.jpg

  7. Trypanosoma Brucei T. brucei gambiense • West African Sleeping Sickness • Chronic, moderate symptoms with delayed onset • Represent more than 90% of sleeping sickness cases T. brucei rhodensiense • East African Sleeping Sickness • Rapid onset of severe symptoms • Intermittent fever within a few weeks

  8. Trypanosoma brucei • Shifts from procyclic to metacyclic to trypomastigotes after exposure • Reproduction occurs through binary fission • Highly aerobic and completely dependent on host glucose for energy • Variant Surface Glycoprotein (VSG) are used to evade antibodies • shields parasitic surface proteins and transport channels • capable of shifting gene expression http://www.medicalecology.org/diseases/d_african_trypano.htm

  9. Symptoms • Early/hemolytic stage • Bouts of fever, headaches, joint pain and itching • Caused by hemolysis due to IgM-antigen complex which binds to ethryocytes • Late/CNS stage • T. b. rhodensiense may advance within a few weeks while T. b. gambiense may take decades • Begins as the parasite crosses the blood-brain barrier resulting in confusion, sensory disturbances, poor coordination, and sleep cycle disturbances

  10. Parasite load changes over time http://www.medicalecology.org/diseases/d_african_trypano.htm

  11. Treatment • Stage dependent • Stage 1: Pentamidine and suramin (few side effects • Stage 2: Melarsoprol– works against both strains but has severe side effects • Eflornithine– Only works against T. b. gambiense but is much less toxic than melarsoprol. • Difficult to apply and requires strict regiment • -New Drugs on horizon

  12. Disease Control • On the Neglected Tropical Disease list • 2000 – WHO partners with Aventis Pharma to provide treatment and free medicine to endemic countries • 2006 – Success of WHO program causes increased private partners to assist in reducing African Trypanosomiasis as a health concern • Still have limited surveillance and diagnostic abilities

  13. Preventative Measures • Insecticides • Bush clearing • Harmful to environment • Game animal killing • Sterile male techniques • Female only mates once • Pheromone-baiting traps • Effective, cheap, nonpolluting, and trusted http://urafikikenya.com/modules/?page=photos

  14. WHO’s 3-step disease management • Screening: Use clinical signs and/or serological assays to find at-risk individuals • Diagnose • Determine stage: Examine cerebral-spinal fluid for parasites • T. b. gambiense requires active and exhaustive screening necessary in at-risk areas • “No universal methodology”

  15. Economic Effects • 3 million cattle die per year; over 35 million doses of trypancidal drugs administered • Under list B of the World Organization for Animal Health (OIE) • High socio-economic or health importance in countries that are significant in international trade • Most economically important livestock disease • loss of ~1 billion per year http://www.jircas.affrc.go.jp/english/publication/annual/1996/intro/images/hl_06.jpg

  16. Bibliography • http://www.britannica.com/EBchecked/topic/401566/nagana • http://www.oie.int/eng/maladies/Technical%20disease%20cards/TRYPANO_TSETSE_FINAL.pdf • http://www.medicalecology.org/diseases/d_african_trypano.htm • http://www.whonamedit.com/doctor.cfm/871.html • http://www.ncbi.nlm.nih.gov/pmc/articles/PMC551439/ • http://www.cdc.gov/ncidod/dpd/parasites/trypanosomiasis/default.htm • http://www.who.int/topics/trypanosomiasis_african/en/ • http://www.who.int/trypanosomiasis_african/diagnosis/en/index.html • http://www.springerlink.com/content/d4jn0e3c1uypa6jl/

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