2. References
• Neva, F. A. & Brown, H. W. 1994. Basic clinical parasitology.
6th Ed. Appilton & Lange Paramount Publishing Business
and Professional Group: USA.
• Steverding, D. 2008. The history of African trypanosomiasis.
Biomed Central. Accessed on Dec. 1, 2015 at http://www.
parasitesandvectors.com/content/pdf /1756-3305-1-3.pdf
• Trypanosomiasis. World Health Organization. Accessed on
Dec. 1, 2015 at http://www.who.int/ mediacentre/factsheets/
fs259/en/
• Parasites – African trypanosomiasis. CDC. Accessed on Dec.
1, 2015 at http://www.cdc.gov/parasites/sleepingsickness/
biology.html
3. Scientific Classification
• Domain: Eukarya
• Kindom: Protista
• Phylum: Sarcomastigphora
• Class: Zoomastogophorea
• Order: Kinetoplastida
• Family: Trypanosomatidae
• Genus: Trypanosoma
• Species: T. brucei
• Sub-species: T. b. brucei, T. b. gambiense, T. b. rhodesiense
7. Trypanosoma brucei
• T. brucei causes Human African Trypanosomiasis
(HAT) or sleeping sickness
• T. brucei is not killed by the immune system
because it has a glycoprotein (VSG) coating.
8. Trypanosoma brucei subspecies
• Two subspecies that are morphologically
indistinguishable cause distinct disease patterns
in humans:
1) T. b. gambiense causes West African
trypanosomiasis
2) T. b. rhodesiense causes East African
trypanosomiasis
• A third member, T. b. brucei, under normal
conditions does not infect humans.
9. Vector of T. brucei
• Tsetse fly belongs to the genus Glossina
13. Stages of Infection
• In the first stage, the trypanosomes multiply in
subcutaneous tissues, blood and lymph. This is
also called haemo-lymphatic stage.
• In the second stage, the parasites cross the
blood-brain barrier to infect the central nervous
system. This is known as the neurological or
meningo-encephalic stage.
14. Pathogenesis
• Incubation period: 2 weeks
• Trypanosomal chancre will develop at the site of
bite
• Via lymphatics: enlarged lymph nodes especially
posterior cervical region (Winterbottom’s sign)
• Via blood stream: headache, fever, muscle &
joint pain, irregular erythematous rash
15. Pathogenesis
• Invasion of bone marrow (hypoplastic anemia)
• Enlarged liver & spleen
• Invasion of the CNS: severe headache, mental
apathy, slow speech, deep sleep, coma & death
17. Diagnosis
Disease management is made in 3 steps:
• Screening for potential infection
- involves using serological tests and checking
for clinical signs
• Diagnosing by establishing whether the parasite is
present in body fluids.
• Staging to determine the state of disease
progression.
- entails examining the cerebrospinal fluid
obtained by lumbar puncture.
18. Treatment (according to WHO)
• First stage treatment:
- Pentamidine
- Suramin
• Second stage treatment:
- Melarsoprol
- Eflornithine
- combination treatment of Nifurtimox and
Eflornithine
19. Epidemiology (WHO)
• HAT affects 36 countries in sub-Saharan Africa
• According to the World Health Organization,
HAT causes ~40,000 deaths in Africa annually.
• Cases involving T. b. rhodesiense are much rarer
than those involving T. b. gambiense.
20. Epidemiology (Steverding, 2008)
• The total amount of reported HAT cases has
decreased substantially over time.
• 1998: ~40,000 reported cases; >250,000
actual cases
• 2004: ~18,000 reported cases; between
50,000 and 70,000 actual cases
• 2010: ~7,000 reported cases; ~30,000 actual
cases
Steverding, Dietmar. 2008. The history of African trypanosomiasis. Biomed Central. Accessed on Dec. 1, 2015 at http://www.parasitesandvectors.com/content/pdf/1756-3305-1-3.pdf
