Trypanosoma brucei Flashcards by Kyra Catedral

Subspecies

• Trypanosoma brucei gambiense
• Trypanosoma brucei rhodiense
• Trypanosoma brucei brucei: affects animals

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Other names of T. brucei

• Human African Sleeping Sickness

• Human African Trypanosomiasis (HAT)

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Forms:

– Epimastigote

– Trypomastigote

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Tissues Affected:

Blood
lymph
spleen
CSF

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Multiplication

– Longitudinal binary fission:

Trypomastigote
Epimastigote

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Mode of Transmission

– Majority:

–

Vector borne

Blood transfusion
needle-prick
transplacental
organ transplantation

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• Infective Stage:

• Diagnostic Stage:

Metacyclic Trypomastigote

Trypomastigote

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Vector:

Tsetse Fly (Genus Glossina)

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T brucei gambiense:

– Western and Central Regions of Sub-Saharan Africa

– Primarily affects_____;

– Chronic type (95%)

– Reservoir Hosts: (3)

humans

dogs, pigs and sheep

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– Western and Central Regions of Sub-Saharan Africa

– Primarily affects humans;

– Chronic type (95%)

– Reservoir Hosts: dogs, pigs and sheep

T brucei gambiense

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– East Africa

– Primarily affects cattles and wild animals (Antelopes)

– Humans as accidental host

– Acute type and rapidly fatal (5%)

T brucei rhodesiense:

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• One wing rests directly on top of the other over their abdomen when resting

• Long proboscis extends directly forward

• Large thorax and abdomen that are shorter than wings

Tsetse Fly (Genus Glossina)

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Forms in the Life Cycle of Trypanosoma brucei

• Human:

–_______

• Vector:
________
________
________

Trypomastigote

– Procyclic Trypomastigote
– Epimastigote
– Metacyclic Trypomastigote

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• Polymorphic: slender or short stumpy form
• Flattened, fusiform shape
• Body: tapers anteriorly, blunt posteriorly

• Nucleus: centrally located with large central karyosome
• Kinetoplast: posterior end
• Undulating membrane with single flagellum

Trypomastigote

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• Body: tapers anteriorly, blunt posteriorly
• Nucleus: centrally located
• Kinetoplast: anterior to nucleus

Epimastigote

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When an infected fly bites a human or an animal, the_________ multiply rapidly into the blood and tissues (spleen, lymph nodes and CSF)

metacyclic trypomastigote

Blood trypomastigote is ingested by the vector, it undergoes transformation in the midgut and are called__________

procyclic trypomastigotes

After 15-20 days, the procyclic trypomastigotes transform into______&raquo_space;> migrate to the foregut then into the salivary glands

Epimastigotes

The epimastigotes multiply in the salivary glands&raquo_space;> transform into the

Metacyclic Trypomastigotes

Acute HAT:

manifest few weeks after the exposure to the vector

T. brucei rhodiense

Chronic HAT:

manifest months or years after the exposure to the vector

T. brucei gambiense

: long term persistence of parasites without clinical features

Trypanotolerance

• Local, painful, pruritic, erythematous chancre located at the bite site progressing into eschar that spontaneously resolves within 23 weeks

– More common in Gambian sleeping sickness but can still occur in Rhodesian sleeping sickness

Initial Lesion

Early Stage

• 1-6 months

•______________

– Parasite is proliferating in the blood and lymphatics

– Trypanids: circinate or serpiginous rashes on trunk and proximal extremities

•________ causing tissue damage

– Irregular and remittent fever, headache, joint pain, muscle pain, fatigue, malaise

– RARE: Disseminated intravascular coagulopathy, anemia, myocardial inflammation, renal insufficiency

Hemolymphatic Phase

Toxin is released

EARLY STAGE – Gambian trypanosomiasis – Enlarged, nontender, rubbery posterior cervical lymphadenopathy (sometimes in axillary and supraclavicular region)

Winterbottom’s Sign

Late Phase •_______\ • Involvement of CNS: brain, meninges • Gambian: 3-10 months after initial infection • Rhodesian: few weeks after initial infection • Neurologic Symptoms: seizures, behavioral changes, apathy, headache, sleeping disturbances (daytime somnolence, nighttime insomnia), tremors, defect in speech/reflexes and even paralysis

Meningoencephalitic Phase

Late Phase •_______ – deep delayed hyperesthesia after a slight blow on a bony projection of the body (delayed bilateral pain out of proportion to extent of injury)

Kerandel’s Sign

Late Phase • In later stages, somnolence manifests followed by a deep coma then death • Affected areas: frontal lobes, pons, medulla, perivascular areas • Trypanosomes can evade the immune system through______

antigenic variation

Progression of african tryponomiasis

Blood Lymphatics CNS Death

• Stages in Diagnosis: ________ • Immunologic (serologic) method • Card Agglutination Test for Trypanosomiasis (CARD): preferred ________ • Direct visualization of trypomastigote in the blood or lymph (cervical node), Microhematocrit method, ________ • CSF Examination by lumbar puncture

1. Screening Test 2. Confirmatory Test 3. Staging

• Particles coated with variant antigen of T. brucei complex PLUS Patient Blood = Agglutination

Card Agglutination Test for Trypanosomiasis (CATT)

Confirmatory Test • Demonstration of the______ in the blood, chancre, lymph node aspirate and CSF – Usually done during the early stage

Trypomastigotes

Other Tests in the Acute Phase

• Concentration Method: Microhematocrit

Staging •_______: recommended to all suspected cases of HAT – Definitive: ***Trypanosomes in the CSF*** – Pathognomonic: High IgM level (quantitative or qualitative test) – Others: • Increase cell count: >5/uL • Increase opening pressure – PCR

CSF Examination