Lecture 9 (Trypanosoma) parasitology slides

Parasitology

1. Hemoflagellates

2. Hemoflagellates
Includes important parasites of man and
animals: Trypanosoma, Leishmania
Digenetic life cycle (two hosts)
Vertebrate
Blood-feeding insect

3. Trypanosoma
Trypanosoma :
African trypanosomiasis (sleeping sickness)
American trypanosomiasis (chagas disease)

4. African Sleeping Sickness
Parasite -Trypanosoma brucei ssp
Trypanosoma brucei rhodesiense
Trypanosoma brucei gambiense
Vector -Tse Tse fly
Glossina mortisans (Eastern Africa)
Glossina palpalis (Western Africa)

5. Geographical distribution

6. Morphology
Spindle-shaped
Kinetoplast
Flagella & undulating membrane
Trypomastigote
Epimastigote

7. Epimastigote
(crithidial form) in the
insect
Trypomastigote
(trypanosomal form) in
the mammalian host
Morphology

8. African Sleeping Sickness
The Life Cycle
Human Tse fly
Trypomastigote Trypomastigote
Stumpy Metacyclic
Intermediate Epimastigote
Slender Trypomastigote

9. Life Cycle of Trypanosoma brucei

10. Trypanosoma forms in blood smear from patient

11. Sleeping sickness in man

12. Symptoms of African trypanosomiasis
symptomsorgan Involvedstage
non pustular, itchy, painful
chancre; no scar
skinBite reaction
malaise, lassitude,
insomnia, fever, edema,
lymphadenopathy
blood circulation
and lymph nodes
Parasitemia
personality changes,
shuffling gait, lack of
interest, tremulous speech,
mental retardation,
sleepiness, cardiac failure.
CNS, heartCNS stage

14. Antigenic variation of T.brucei
Trypanosome levels in infected patients show a
cycle of sharp peaks and valleys in parasite
numbers of approximately a week in length.
The cycle occurs because the immune system
recognizes the glycoprotein in the
trypanosomes coat and mounts an immune
response to it, which eliminates parasites with
that glycoprotein.

15. Antigenic variation of T.brucei
Trypanosomes, however, possess about 1,000
different coat-building genes and periodically a
new one is turned on by a trypanosome that
produces a different coat, which the immune
system doesn’t recognize.
Trypanosomes with this new coat reproduce
undetected until the immune system can mount
a response to the new coat.

16. Antigenic variation of T.brucei

17. African Sleeping Sickness
Virulence
Zoonotic
Vector
Distribution
Less More
Less More
G.palpalis G.mortisans
Western AfricaEastern Africa
T.b.gambiense T.b.rhodesiense

18. T.brucei diagnosis
History of travel and
fly-bite
Symptoms
Blood smear and/or
CSF

19. T. brucei:
Prevention and treatment
No effective vaccine
(changing VSG)
Tsetse fly control
Insect-bite avoidance
Suraminor
pentamidine
Acute disease
Suramin
Pentamidine
Chronic (CNS)
disease
Melarsoperol(arsenic)
Prevention Treatment

20. American trypanosomiasis
Parasite: Trypanosoma cruzi
Vector: the blood-sucking Triatoma
infestans(reduviid bug)

21. Geographical distribution

22. Morphology
T.cruzi has three morphological forms:
The trypomastigote -present in blood stream
The epimastigote -stage that occurs in the vector
The amastigote -present within cells

23. Morphology

24. Tryptomastigote -outside the
cells

25. Amastigotes -inside the cells

26. Life cycle of T.cruzi

27. symptomsorgan
involved
stage
nonpurulent edematous plaque
with edema
skinPrimary
lesion
malaise, restlessness,
lymphadenitis, hapatomegaly,
splenomegaly, acute myocarditis,
generalized edema
lymph node
and heart
Acute stage
Mega esophagus, mega colon,
cardiomegaly, cardiac arrhythmia
hollow organsChronic stage
Symptoms of American trypanosomiasis

29. Chagas disease diagnosis
History of travel and
sometimes cardiac
problems
Romamna’ssign or
chagoma
Organisms in the
chagomaexudate, lymph
node aspirate or blood

30. Prevention and control
Vector control
Urbanization: vector habitat elimination