Trypanosoma gambiense
Phylum- Protozoa SubphylumSarcomastigophora Superclass- Mastigophora Class- Zoomastigophora Order- Kinetoplastida Genus- Trypanosoma Species- gambiense
HABIT & HABITAT
Discovered by Forde in 1901
Sir David Bruce: sleeping sickness is caused by tse-tse fly
Confined mainly to the Central & West African regions
Causes African Sleeping Sickness in man
Parasite lives in blood & lymph glands
Later invades CSF: fever, anemia, lethargy & death
Chief vector: tse-tse fly,
Glossina palpalis
Dogs, pigs, buffaloes : temporary /reservoir hosts
Parasite doesn’t develops but waits for human host
Entry into humans: bite of tse-tse fly
Fly feeds on blood of humans /reservoir hosts
morphology
Unicellular leaf-like, elongate, tapering
Polymorphic occurs in two forms
Trypanosome Crithidial
Trypanosome form: blood of man
Crithidial form: Salivary glands of tse-tse fly
Body is covered by thin, elastic & firm pellicle
Pellicle: (Microtubules) maintains shape of body
Uniflagellate, flagellum arise from basal body (posterior end of body)
Runs across whole length of body, attached/ free at the anterior end
T.S. usual 9+2 pattern of fibrils
During locomotion, attached end of Flagellum pulled up
Fold: undulating membrane
Cytoplasm: enclosed within pellicle
Cytoplasm ectoplasm & endoplasm
×
All the cell organelles√
Food stored in glycogen & phosphates
Lysosomes secrete hydrolytic enzymes
Nucleus large, oval, double membraned centrally placed
Electron Microscopic view
Sexual reproduction unknown
Asexual reproduction by longitudinal binary fission
Kinetoplast & blepharoplast divide first, become paired
Old flagellum attached & new one starts growing from blepharoplast
Nucleus divides mitotically into 2 daughter nuclei
Body splits midlongitudinally into 2 daughter trypanosomes
LIFE CYCLE
Primary host: man
Intermediate host:
Glossina palpalis (tse-tse fly)
Reservoir hosts: pigs, dogs, antelopes
IN MAN
Infection: initiated by bite of the fly
Fly harbours metacyclic forms (salivary glands)
While feeding on human blood transfers trypanosomes
Blood clotting prevented by anticoagulant
All the stages of parasite: extracellular
Present in the plasma only
Metacyclic forms become long slender forms
Swim freely by beating of flagellum
Multiply by longitudinal binary fission
Energy for division: anaerobic glycolysis
If Glucose deficiency prevails multiplication hampered
Long, slender forms short, stumpy, flagella devoid forms
Stop feeding taken by tse-tse fly through blood
IN TSE-TSE FLY
Tse-tse fly takes short, stumpy forms with blood meal
Further development occurs in peritrophic membrane of midgut
Parasite transforms into long, slender form
Divides by longitudinal binary fission
Energy by mitochondrial oxidation of pyruvic acid
Migrate to salivary glands & transform to crithidial forms
Have shortened body, reduced free flagellum & kinetoplast
Multiply in salivary glands into metacyclic forms
Ready to infect humans
Transferred to human blood by bite of the fly
SLEEPING SICKNESS
Also called as Trypanosomiasis
Bite of fly causes local irritation
First symptom: Irregular, recurrent fever
Weakness, loss of weight, anemia
Increased pulse rate, severe headache
Patient falls asleep & undergoes coma, finally death
Trypanosomes can be detected in stained blood
Parasites may be obtained from CSF
Common drugs Suramin sodium, Bayer 205
Eradication of vector control spread of disease
POLYMORPHIC FORMS
4 forms:
1.Leishmanial (Amastigote) round, flagellum reduced fibril-like
2.Leptomonad (Promastigote) Elongate, flagellum short , unattached
3.Crithidial (Epimastigote) Elongate, undulating membrane inconspicuous
4.Trypanosomid (Trypomastigote) Elongate, undulating membrane conspicuous
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