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Bio 51Parasitology
Trypanosoma bruceiPrepared by:
NOE P. MENDEZCENTRAL MINDANAO UNIVERSITY (CMU)
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
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
Trypanosoma brucei Morphology
Trypanosoma brucei•micrograph under SEM:
Trypanosoma brucei•stained under bright-field microscope:
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.
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.
Vector of T. brucei
• Tsetse fly belongs to the genus Glossina
Geographical Distribution of African Trypanosomiasis
G.palpalis G.morsitans
In West Africa In East Africa
T. brucei Life Cycle
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.
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
Pathogenesis•Invasion of bone marrow (hypoplastic
anemia)
•Enlarged liver & spleen
• Invasion of the CNS: severe headache, mental apathy, slow speech, deep sleep, coma & death
Winterbottom sign
Trypanosoma chancre
Coma before death
DiagnosisDisease 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.
Treatment (according to WHO)•First stage treatment:
- Pentamidine- Suramin
•Second stage treatment:- Melarsoprol- Eflornithine- combination treatment of
Nifurtimox and Eflornithine
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.
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
End of Report
