African Sleeping Sickness African Trypanosomaisis http://phil.cdc.gov/phil/details.asp
Feb 09, 2016
African Sleeping Sickness
African Trypanosomaisis
http://phil.cdc.gov/phil/details.asp
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 humansin 1902.
History
http://www.uoguelph.ca/~pwoo/animaltryp.jpg
Sir David Bruce Worked in Ubombo, South
Africa with wife Mary
Discovered both trypanosome and transmission by tsetse fly in 1903
‘trypanosome fever’ = ‘sleeping sickness’
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
Epidemiology
Glossina/Tsetse flies
http://www.medicalecology.org/diseases/d_african_trypano.htm#sect5.3
Human African Trypanosomiasis
http://www.stanford.edu/class/humbio103/ParaSites2001/trypanosomiasis/trypanpo_files/image044.jpg
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
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
Trypanosoma brucei
http://www.medicalecology.org/diseases/d_african_trypano.htm
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
Symptoms
Parasite load changes over time
http://www.medicalecology.org/diseases/d_african_trypano.htm
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
Treatment
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
Insecticides
Bush clearing◦ Harmful to environment
Game animal killing
Sterile male techniques◦ Female only mates once
Pheromone-baiting traps◦ Effective, cheap, nonpolluting, and trusted
Preventative Measures
http://urafikikenya.com/modules/?page=photos
Screening: Use clinical signs and/or serological assays to find at-risk individuals
Diagnose Determine stage: Examine cerebral-
spinal fluid for parasites
oT. b. gambiense requires active and exhaustive screening necessary in at-risk areas
o “No universal methodology”
WHO’s 3-step disease management
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
Economic Effects
http://www.jircas.affrc.go.jp/english/publication/annual/1996/intro/images/hl_06.jpg
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/
Bibliography