Search for notes by fellow students, in your own course and all over the country.
Browse our notes for titles which look like what you need, you can preview any of the notes via a sample of the contents. After you're happy these are the notes you're after simply pop them into your shopping cart.
Title: Laboratory DIangosis of Trypanosomiasis and Leishmaniasis
Description: This is an overview of the biology and laboratory diagnosis of Trypanosomiasis and Leishmaniasis, which are the most clinically important human hemoflagellates.
Description: This is an overview of the biology and laboratory diagnosis of Trypanosomiasis and Leishmaniasis, which are the most clinically important human hemoflagellates.
Document Preview
Extracts from the notes are below, to see the PDF you'll receive please use the links above
HEMOFLAGELLATES
•
Members of the group Kinetoplastea
•
Two medically important genera:
o Leishmania
o Trypanosoma
•
Kinetoplastid – complex of abundant circular DNA within
mitochondrion
o visible with Giemsa stain under light microscopy
o Assumes different morphology depending on presence of
hosts or insect vector
•
Transported via insect vector
1
...
Cruzi or Leishmania – multiply intracellularly
exclusively
2
...
Brucei
Old world/African
30 ɥm
Graceful curves
Smaller kinetoplast
Leishamnia amastigote
•
•
•
•
Promastigote
•
•
•
•
Epimastigote
•
•
•
Trypomastigote
•
•
Elongated, slender
Central nucleus
Anterior kinetoplast and axoneme
Free flagellum extending from anterior
end
Occurs in insect vectors of Leishmania
(tsetse fly); Stage detected in cultures,
not seen in humans
not detected in clinical specimens unless
there is a substantial delay in processing
Kinetoplast found closer to the nucleus
Small undulating membrane → free
flagellum
All human-infecting Trypanosoma
assume epimastigote stage in in cultures
and vector, not seen in humans
Kinetoplast found on the posterior end
Flagellum extends along entire length as
undulating membrane + free flagellum at
the anterior end
Occurs predominantly in bloodstream of
mammalian host infected with
Trypanosoma
Metacyclic trypomastigote - infectious
stages found in appropriate insect
vectors; can undergo binary fusion
T
...
Rangeli
•
Has been described in humans in the Americas
•
does not cause clinical illness
T
...
Brucei
T
...
Brucei Gambiense
East African Trypanosomiasis
Acute Disease
West African Trypanosomiasis
Chronic Disease
2% of cases
Vector: G
...
Palpalis
Humans are primary reservoir
“African Sleeping Sickness”
Chronic course
Intermittent fevers, night
sweats, malaise
Winterbottom sign – posterior
CLAD
Confusion, fatigue → stupor
and coma
Area of initial bite of Tsetse fly → local multiplication → transient
chancre at bite site
Reduvid bug
•
Diagnosis
•
Based on geography and clinical findings
•
CSF
o ↑ total IgM
o Pleiocytosis: 50 to 500 mononuclears/ɥL of CSF
•
Identification of parasites via:
o (1) thick and thin smears
o (2) buffy coat preparations
o (3) lymph node and bone marrow aspirate
o (4) centrifuged CSF with Giemsa stain
•
Culture, Animal inoculation
•
Molecular Methods
Life Cycle:
o Inoculation
o Enters nearby tissue cells → becomes dividing amastigotes
o Infected cells filled with amastigotes → transformation to
trypomastigote
o Cell rupture → trypomastigote are released into the
peripheral blood → reach distant tissues
Life Cycle
Acute Manifestations
•
Most common: children <5 y/o
•
Malaise hills fever, hepatosplenomegaly and myocarditis
•
Romana’s Sign – swelling of tissues around the eyes
American Trypanosomiasis
Trypanosoma Cruzi: Chaga’s Disease
•
Transmission: “kissing bugs” - Reduviidae
o Reduviid bugs defecate at time of feeding (contains the
trypomastigotes)
o Rubbing and scratching → enters the body or though intact
mucosa of the mouth or conjunctiva
o Can also be transmitted by blood transfusion
•
•
Chagoma – swelling around bite site of reduviid bug
Disease is milder and more asymptomatic in older individuals –
remains infected throughout life
Chronic Disease
•
Megaesophagus, megacolon, hear conduction problems
•
Related to destruction of the effector cells of the
parasympathetic system
•
Quiescent infections may be exacerbated by immunosuppression
T
...
LEISHMANIA
•
Animal reservoir
•
Transmission via: Sand flies; acquired in horses, wild animals as
reservoirs
o Old World: genera Phlebotomus
o New World: genera Lutzomyia
•
Amastigote form in mammalian host, promastigote in insect
vector
T
...
g
...
cruzi infection requires
reactivity on two tests using two different methodologies
and/or two different T
...
Tropica
L
...
Major
May become viscerotopic
•
“rural or wet ulcer”
•
More aggressive cutaneous infection, may
also form diffuse cutaneous leishmaniasis
Multiple skin nodules resembling
lepromatous leprosy
L
...
Donovani
L
...
Amazonensis
•
May produce diffuse cutaneous lesion
•
“uta” - Benign cutaneous lesion
primarily occurring in children
Domestic dogs – main reservoir
•
miltefosine
Visceral Leishmaniasis
New World
L
...
Peruviana
•
•
•
L
...
Infantum
L
...
g
...
venezeuelensis
L
...
pifanoi
L
...
hyanensis
Treatment of cutaneous leishmaniasis
•
endemic settings outside of the Americas
o no risk of mucosal dissemination
o cosmetically unimportant lesions may be treated topically
(e
...
, cryotherapy) or allowed to self-heal
•
For individuals at risk of aggressive, disfiguring, or disseminated
disease
•
systemic therapies with sodium stibogluconate
•
meglumine antimoniate
•
miltefosine
•
paromomycin – both oral and topical forms may also be used
Mucocutaneous Leishmaniasis
•
Caused by: (1) L
...
g nasal, oral, and pharyngeal mucosa
•
Treated with
o sodium stibogluconate
o
amphotericin
Leishmania amastigotes
•
•
•
Smears: 2 to 3 mm incision at the border of lesion
o Recover small amount of tissue from cut surface
o Smear and imprint must be treated with Giemsa stain
Biopsies should be submitted to histopathology and/or submitted
for culture
Visceral Leishmaniasis:
o (1) buffy coat preparations;
o (2) LN and BM aspirates;
o (3) spleen and liver biopsies
Tissue biopsy
Culture
•
More sensitive
•
Allows for identification of species/subspecies
•
Culture medium:
o Novy-MacNeal-Nicolle Medium
o
•
•
Schneiders Drosophila Medium supplemented with calf
serum
Detection of (+) promastigote in 2 to 5 days
Culture should be held for 4 weeks
Promastigotes in culture
•
Amastigotes can be found in imprints, smears, and tissue sections
o Morphology: Small size (2–4 μm); delicate cytoplasm;
nucleus; kinetoplast
o may appear smaller in In tissue sections due to shrinkage
during fixation
o must be differentiated from other intracellular organisms e
...
yeast cells of H
...
gondii trophozoites
Leishamania Amastigotes; kinetoplast (arrow)
•
•
Differential diagnosis: H
...
and T
Title: Laboratory DIangosis of Trypanosomiasis and Leishmaniasis
Description: This is an overview of the biology and laboratory diagnosis of Trypanosomiasis and Leishmaniasis, which are the most clinically important human hemoflagellates.
Description: This is an overview of the biology and laboratory diagnosis of Trypanosomiasis and Leishmaniasis, which are the most clinically important human hemoflagellates.