Trypanosoma

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Trypanosoma
Introduction
1- Extracellular in BLOOD TISSUES
2- West African Trypanosomiasis West African
Sleeping Sickness caused by T. brucei
gambiense.
3- East African Trypanosomiasis East African
Sleeping Sickness caused by T. brucei
rhodesiense.
4- Chronic form caused by T. brucei gambiense.
While Acute Form is caused by T. brucei
rhodesiense.
5- African Sleeping Sickness is the 3rd important
parasitic disease globally after Malaria
Schistosomiasis
6- West African Sleeping Sickness is in regions
along riverside while East African
Sleeping Sickness is in Forest regions
(Savannas).
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Trypanosoma
Causes
Trypanosomiasis
American Trypanosomiasis
East African Trypanosomiasis
West African Trypanosomiasis
T.brucei rhodesiense
T.brucei gambiense
T.cruzi
Sleeping sickness
Chagas disease
Transmitted by
Transmitted by
Glossina (tsetse fly)
Triatoma (winged bug)
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Trypanosoma
Morphology
Exist into 2 interchangeable forms
Trypomastigote in Blood/ Lymph / tissue space of
various organs C.N.S is terminal fatal
Epimastigote in salivary gland of vector
Culture media.
Trypomastigote (Polymorphic Trypanosomes
Spindle shaped Central nucleus free flagellum
undulating membrane.
3 forms
1- long Slender Form (30µ) active motile with
free flagellum.
2- Short stumpy Form (15µ) sluggish without free
flagellum.
3- Intermediate Form (20µ) with a short free
flagellum.
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Geographical Distribution of African
Trypanosomiasis
G.palpalis
G.morsitans
In West Africa
In East Africa
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Trypanosoma brucei causing Sleeping Sickness
West Africa
East Africa
T.brucei gambiense
T.brucei rhodesiense
Less plentiful
More plentiful
Cannot live in lab animals
Can live in lab animals
Nucleus is shifted posteriorly
Reservoir host goats, cattle pigs
Reservoir host wild game
animals
Transmitted by G.palpalis
Transmitted by G.morsitans
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Mechanism of disease transmission by Glossina
Trypomastigotes (polymorphic
trypanosomes)
Diagnostic stage
12-42µ
Bite of ? ? Glossina
3 weeks
Salivary gland
Epimastigote
Full of short stumpy metacyclic Trypomastigote
Infective stage
Biological transmission
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African Trypanosomiasis life cycle
Life cycle of Trypanosoma brucei gambiense T.
b. rhodesiense
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African Trypanosomiasis life cycle
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African Trypanosomiasis life cycle
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Pathogenesis and Clinical Picture
Incubation period (2 weeks)
Trypanosoma chancre (at the site of bite)
Via lymphatics enlarged lymph nodes especially
posterior cervical region.
(Winterbottoms sign)
Via blood stream headache, fever(fluctuating),
muscle joint pain, irregular erythematous rash.
Invasion of bone marrow
(hypoplastic anaemia)
Enlarged liver spleen, generalized weakness.
severe headache,
mental apathy, slow speech, deep sleep, coma
death
Invasion of CNS
In East African Trypanosomiasis
Disease runs more rapid fatal course
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Pathogenesis and Clinical Picture
Winterbottom sign
Trypanosoma chancre
Emaciation ??? ??? ???
Coma before death
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Clinical Picture
Progressive disease may lead to the following
C.N.S manifestations-
1- Insomnia ???
2- Mood changes (dullness ????? / apathy ???????)
3- Motor Sensory Disorders (Hyperesthesia ???
???? / slurred speech ???? ?????? / abnormal
gait ???? ??? ??????).
4- Convulsions
5- Epilepsy ??? ?????
Terminal stage
1- Permanent Sleep. 2- 2ry Bacterial
infection. 3- Coma Death.
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Diagnosis
1- Clinical picture
2- Demonstration of trypanosomes
Polymorphic Trypanosomes
- Microscopic examination of
unstained or stained blood films
- Culture on suitable medium (N.N.N OR
Weinmanns media to detect Epimastigote)
- Animal inoculation
N.B. in case of T.brucei rhodesiense injected in
lab Animal produce a new form Posterior Nucleus
Shift
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Diagnosis
C.S.F
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Diagnosis
3- Serological test
Increased total IgM level in serum due to
antigenic variation of the surface coat of the
parasite.
Trypanosome posses genes that code for about 1000
variant forms of their surface glycoproteins
(SVG). Switch to a different variant produces a
new generation not susceptible to attack by
immune factors specific to the previous
generation.
Trypanosomes can evade(????) the immune system
????? ?????Why in African Trypanosomiasis
infection, there is a sustained elevated IgM
level ???????
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Trypanosoma cruzi causing Chagas disease
Winged bug
Prominent kinetoplast
Kissing bug
Triatoma or Rhodnius
Trypanosoma cruzi
C-shaped
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Trypanosoma cruzi
Morphology
Trypomastigote (Monomorphic)
Slender shaped (20µ) Central nucleus C or
U-shaped Free flagellum 1/3 body- Large bulging
peripheral kinetoplast
Amastigote
Obligatory intracellular mainly in cardiac
Skeletal muscles Brain meninges Nerve ganglia
cells of GIT . etc
Epimastigote (Vector only)
Spindle shape Kinetoplast anterior to central
nucleus Undulating membrane is short terminal
free flagellum
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Mechanism of disease transmission by winged bug
T.cruzi in human blood
Cyclopropagative transmission
Alimentary canal of bug
Short stumpy metacyclic trypomastigote (infective
stage)
Epimastigote form
Pass out with faeces
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AMERICAN TRYPANOSOMIASIS
LIFE CYCLE OF Trypanosoma cruzi
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Mode of infection
Mainly by

• Contamination of skin abrasion
  (???? ??????) by winged bug faeces
• Cone nose Bug kissing Bug Assassin bug

Rarely by
Through infected blood transfusion
Through infected mothers milk
Through the placenta
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Life cycle of Trypanosoma cruzi
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Life cycle of Trypanosoma cruzi
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Pathogenesis and Clinical Picture
I- Acute Form
Chagoma occurs at the site of bite.
Parasite reaches regional lymph nodes
To
Blood
To
Organs and tissues
Fever, enlarged lymph nodes, skin rash, enlarged
liver spleen.
Romanas sign (Unilateral conjunctivitis appear
suddenly together with oedema of upper lower
eye lids cheek)
Meningoencephalitis, heart failure
Death or pass to Chronic form
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II- Chronic form
Pathogenesis and Clinical Picture
Parasite produces antigens similar to patients
self antigens
Amastigote form of T.cruzi
The body produces auto-antibodies that cause
damage to

• Heart muscle fibres

congestive heart failure.

• Oesophageal muscle fibres ??? ?????

megaoesophagus and dysphagia. Destruction of
Auerbachs plexus

• Colon muscle fibres

megacolon and constipation.

• CNS or thyroid gland

Exacerbation of infection in
immunosuppressed patients.
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Diagnosis
Finding the parasite in
Blood film (C-shaped T.cruzi)
Biopsy from lymph node, liver or spleen
(amastigotes)
Culture (Epimastigotes)
Xenodiagnosis
Serological tests
Cruzin test (I.D.)
Molecular techniques
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Diagnosis (Xenodiagnosis)
Highly efficient demonstrate low level of
parasite in blood
Method
A Laboratory bred winged bug is starved for 2
weeks then fed on suspected patients blood 30
days later, it faeces gut examined for
trypanosomes.
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Diagnosis
Winged Bug
Trypomastigote
Amastigote
Chagoma
Romanas sign
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Treatment
Sleeping Sickness
Chagas Disease

• In early stage of the disease
• Pentamidine OR Suramin
• In late stages of the disease
• Tryparsamide
• For both early and late stages of the disease
• Eflornithine (DFMO) Ornidyl

• Nifurtimox
• inhibits intracellular development .
• Drug of choice in acute and early chronic
• OR
• Primaquine
• destroys Trypanosoma in blood

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Control
Chagas disease
Sleeping Sickness

• Treatment of patients
• Control of vectors (Triatoma)
• Elimination of reservoir hosts

• Treatment of patients
• Control of vectors (Glossina)
• Pentamidine as prophylactic drug

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M.C.Q.
Protozoal infections that may cause fever and
hepatosplenomegaly

• a- Visceral leishmaniasis
• b- African trypanosomiasis (sleeping sickness)
• c- American trypanosomiasis (Chagas disease)
• d- Non of the above
• e- All of the above

Smear taken from the edge of oriental sore
reveals
a- promastigote
c- amastigote
d- trypomastigote
b- epimastigote
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M.C.Q.
Protozoa causing conjunctivitis include
a- Trypanosoma cruzi
b- T.brucei gambiense
c- T.brucei rhodesiense
d- Leishmania donovani
Winterbottoms sign is seen in
a- Cutaneous leishmaniasis
b- Visceral leishmaniasis
c- African trypanosomiasis
d- American trypanosomiasis
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M.C.Q.
In African trypanosomiasis, the infective stage
is found in
Short stumpy metacyclic trypanosomes
a- Saliva of Triatoma
c- Stool of Triatoma
b- Saliva of Glossina
d- Stool of Glossina
Posterior nuclear shift occurs in
a- Trypanosoma cruzi
b- Trypanosoma gambiense
c- Trypanosoma rhodesiense
d- Trichomonas vaginalis
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M.C.Q.
In chronic Chagas disease, the main lesions are
in
a- Digestive and respiratory tracts.
b- Heart and liver.
c- Heart and digestive tract.
d- Liver and spleen.
Megacolon associated with Chagas disease
a- Is manifested by diarrhoea.
b- Occurs early in the disease.
c- Is due to oedema of the mucosa.
d- Is associated with constipation.
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Compare between
Romanas sign
Acanthamoeba affection of the eye
Inflammation of the conjunctiva
Inflammation of the cornea
Ulceration
Perforation
Ocular pain affection of vision
Mode of infection
Occurs through corneal trauma
Contamination of skin abrasions by winged bug
(Triatoma) faeces
Exposure to contaminated water
Wearing contaminated contact lenses
Short stumpy metacyclic trypanosomes