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HEMOFLAGELLATES
Dr. R.E. Tan
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Blood & Tissue Dwelling Protozoa(Hemoflagellates)
Family : Trypanosomatidae
Genus :A. Leishmania - tropica
- braziliensis- donovani
B. Trypanosoma - gambiense- rhodesiense- cruzi
C. LeptomonasD. HerpetomonasE. PhytomonasF. CrithidiaG. Blastocrithidia
Pathogenic toman
parasitic in insects
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Protozoan Class Kinetoplasta
General characteristics of Hemoflagellates:
Minute, actively motile
flattened side to side, tapering anterior and blunt posterior end
Distinguished structures:
Kinetoplast
Members of this group are characterized by a single large
mitochondrion containing a body kinetoplast Located at the base of the flagellum
A disc-shaped, DNA-containing organelle within themitochondrion
Undulating membraneThin protoplasmic sheet running along 1 side
Flagella - single anterior flagellum which travels in a wavy spiralmotion; arising from a kinetoplast near the anterior end
Nucleus
reproduce by binary fissionnourishment is attained from blood, plasma, lymph, CSF and
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Epimastigoteelongate, spindle-shaped body, longer
single nucleus with central karyosome the kinetoplast is more centrally located,
usually just anterior to nucleus The single free flagellum emerges from the middle of the parasite and forms a shorter undulating membranerepresented by Genus Crithidia andBlastocrithidia
Trypomastigote kinetoplast is located at the posterior end the attachment of the flagellum to the body
forms an undulating membrane that spansthe entire length of the parasite and the
freeflagellum emerges from the anterior end
represented by Genus Trypanosoma
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obligate intracellular parasite capable of causing human disease
all species are morphologically identical
differentiation among species causing disease in human is based
on clinical groundsVarious species are transmitted by sandflies
Old World: genus Phlebotomus
New World: genus Lutzomyia
Vertebrate hosts: primarily mammals (humans, dogs, some
rodents)
Causes a complex disease called Leishmaniasis
Genus
Leishmania
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Part of their life cycle is spent in a sand fly gut, where theybecome promastigote; the remainder of their life cycle iscompleted in vertebrate tissues, where only amastigotes arefound
1) Amastigote
- present in the vertebrate host (human)
- always found intracellularly in the cells of thereticuloendothelial system, at times are
present in the blood stream in large
mononuclear cells - ovoid / rounded bodies measuring2 3 m wide
- non-flagellated
- traditionally known as Leishman-Donovan (L-D)bodies
- amastigotes cannot be differentiated from otherLeishmania specie on the basis of
morphology alone
2) Promastigote
- present in the invertebrate host (sandfly)- infectious form
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Life Cycle ofLeishmania
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ClinicalDisease
OrganInvolved
Leishmaniaspecie
GeographicalLocationCutaneous
Leishmaniasis
skin L. Tropica Complex L. tropica
L. aethiopiaL. major
L. Mexicana complex L. mexicana
L. pifanoiL. amazonensis
L. Braziliensis complexL. peruvianaL. guyanensisL. panamensisL. lainsoni
L. columbiensisL. InfantumL. chagasi
Old World
New World
New World
Old WorldNew World
MucocutaneousLeishmaniasis
skin & mucousmembrane
L. Braziliensis complex L. braziliensis
L. guyanensisL. panamensis
L. MexicanaL. tropicaL. major
New World
New WorldOld WorldOld World
VisceralLeishmaniasis
visceral organs L. Donovani complex L. donovani
L. infantumL. chagasi
L. TropicaL. amazonensis
Old WorldOld WorldNew worldOld WorldNew World
Leishmania Species and the Clinical Diseases TheyCause
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Old world cutaneous leishmaniasis
Caused by Leishmania tropica Complex vector: sandfly of genus Phlebotomus (P. papatasi & P.
sergenti)
Leishmania major produce an acute infection with a 3-6 months duration, lesions
occuring in the lower limbs, associated with moist lesionswhich tend to ulcerate very early
Wet or Rural Cutaneous Leishmaniasis
seen in Turkmenistan, Iran, Syria, Israel, Jordan, Africa, Egypt,Tunisia, Sudan, Nigeria, Mali and Kenya
Leishmania tropica produce a chronic disease that if not treated, lasts for a year or
longer
characterized by dry lesions that ulcerate only after severalmonths
usually single and appear in the face
Dry or Urban Cutaneous Leishmaniasis
distributed around the Mediterranean littoral, Armenia,Azerbaijan, Turkmenistan, Uzbekistan; also in Afghanistan,
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New world cutaneous leishmaniasis
vector: sandfly of genus Lutzomyia
Caused by species of the Leishmania mexicana Complex:
Leishmania mexicana
associated with Chiclero ulcer
Leishmania pifanoi occurs in Amazon basin, Brazil and Venezuela
initial lesion is single, and often a period ofmonths or years passes (during which mayulcerate or disappear) before the disease spreadsboth locally or to distant skin areas
Caused by species of the L. braziliensis complex
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In South America, the lesions of Cutaneous Leishmaniasis havetheir own names and clinical expressions:
Uta
Common in Peru (western Peruvian Andes)
caused by L. peruviana Appear as a solitary ulcer or a few restricted lesions,
frequently in the face; necrosis involving the nasal systemand buccal mucosa
Bush Yaws or pian bois
Common in Guyana
Caused by L. guyanensis
Appear as raspberry-like lesions that resemble yaws
Chiclero Ulcer or Bay Ulcer
Common in Mexico,, Yucatan peninsula, and Guatemala
In Belize - called Bay Ulcer/sore
Caused by L. mexicana lesions appear single, usually in the ear where they can
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Symptoms:
Incubation periodL. tropica & L. aethiopica: couple of months 3 years
L. major: 2 weeks
1st sign of infection: small red papule at the site of the bite,which may itch intensely and grows to2cm in diameter or more
L. tropica & L. aethiopica papule is dry and ulcerate onlyafter several months
L. major papule is covered with a serous exudate & ulcerateearly
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Usual cutaneous lesions healsspontaneously
certain instances such healing does not
occurAnergic patient
incapable of mounting a response toinfection which can proliferateindefinitely, forming many lesions
teeming with parasites Causes Diffuse Cutaneous
Leishmaniasis
Due to deficient cell-mediatedimmunity and of some characteristicsof the parasite itself (L. aethopica & L.pifonoi)
Hypersensitive patient Capable of excellent antibody and
cellular responses but cannotcompletely eliminate the parasite, so
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primary lesion:Small red papule
gradually enlarges
soft at center
Rupture
ulcer formation
(large, raised w/ indurated edges)Swollen lymph nodes may be present near
the soresulcer may be single / multiplemost often seen on exposed area of body
(extremities, face, ear, hands)secondary bacterial infection is commonnew world cutaneous leishmaniasis tends to
be more
severe and chronic than old world cutaneous
leishmaniasis
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Pathogenesis:
bite of an infected sandfly
liberates promastigote into the skin
the parasite proliferate as amastigotes in the
macrophages and endothelium of the capiliaries and othersmall blood vessels of the intermediate area
Lysis of the amastigotes occurs following activation of themacrophages by sensitized lymphocytes
A granulomatous reaction results in the formation of alocalized nodule, which ulcerates when the blood supply to
the area is compromised by parasite-induced damage
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Diagnosis:Diagnosis is usually made in endemic areas on clinical
grounds, but requires much familiarity with the diseaseDemonstration of parasite from tissue smear or aspirationof
exudate from ulcer edge
Wright/ Giemsa stain
demonstrate amastigote stage
inside mononuclear cells
Culture on: NNN medium (Novy-MacNeal-Nicolle)
Schneiders Drosophila mediumAspirate or biopsy of ulcer may be inoculated
subcutaneously into the nose of a hamster and the animalwatched for nasal inflammation
Serology Indirect flourescent Antibody test
Dermal test (Montenegro skin test) intradermal injection of
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Treatment:2. Pentavalent Antimonial compounds:
Sodium stibogluconate (Pentostam)- is the drug of choice for all types of leishmaniasis
- Given under an experimental protocol atWalter Reed Army Medical Center (WRAMC)
- 20mg/kg for 20 days of intravenous therapyMeglumine antimonate (Glucantime)
- 50mg/kg daily for 10-12 days- used in areas where Pentosam is not available
2. Fluconazole - may increase healing time in L. majorinfection
3. Liposomal amphotericin-B (AmBisome
) used in patientsunresponsive to pentavalent antimonials4. Itraconazole used in India to treat cutaneous leishmaniasis
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Synonyms: Espundia / American leishmaniasis
Most common causative agent: Leishmania braziliensisGeographical Dist. : Central & South America, Brazil, Eastern Peru,
Bolivia, Parugay, Ecuador, Colombia,Venezuela
In Brazil known as Espundia
involves the skin with development of ulcers in the mouth or nasamucosa
not found in the peripheral blood rarely localized in visceral organMode of transmission: bite of a female sandfly
Old world - genus Phlebotomus
OrganInvolved Leishmaniaspecie GeographicalLocationskin & mucous
membraneL. Braziliensis complex L. braziliensis
L. guyanensisL. panamensis
L. MexicanaL. tropicaL. major
New World
New WorldOld WorldOld World
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Primary lesion:
Lesions produced by the parasite appears 1-
4 weeks after the bite Appearance of small red papule at site of the
bite
Becomes itchy, ulcerated vesicle developexactly the same with Oriental sore, but theyare more frequently multiple and maybecome very large
Heals within 6-15months
Secondary lesions:
development of ulcers on the oral or nasal ormucopharyngeal mucosa causing highlydisfiguring tissue destruction & swelling
deformity of the cheeks, lips, soft & hardpalate
symptoms include: fever, weight loss, anemia,weakness, and he atos lenome al
Symptoms:
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Diagnosis :Smear from ulcer demonstrate amastigote stage in
affected tissues
Morphology: similar appearance with other Leishmania specie
Intradermal test (Montenegro test)
Culture NNN medium
Treatment:1. Antimonial compounds:
Sodium stibogluconate (Pentostam)
Meglumine antimonate (Glucantime)
2. Clycoguanil pamoate (Camolar) a folic acid inhibitor
300mg IM single dose (adult)280mg (1-5 years old)
140mg (infants)
3. Amphotericin-B (Fungizone) 0.25-1mg/k IV daily for 8 wks
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Synonyms: Kala-azar/ Death fever / Black disease
Dumdum Fever/Tropicalsplenomegaly
Most common causative agent: Leishmania donovani complex L. donovani - India, Burma, East Pakistan, Sumatra, Thailand,
Southern Russia, East Africa, Ethiopia, Sudan,
North ChinaL. chagasi Cental and South America (vector: Lutzomyia)
L. infantum Europe, Africa, China and Siberia
Insect vector: sand flies (genus Phlebotomus )
Site of involvement: amastigotes live within cells of the
reticuloendothelial system including the spleen, liver,
OrganInvolved
Leishmaniaspecie
GeographicalLocationvisceral organs L. Donovani complex
L. donovaniL. infantumL. chagasi
L. TropicaL. amazonensis
Old WorldOld WorldNew world
Old WorldNew World
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Symptoms:Onset of disease is gradual
incubation period 2weeks-18months or longer
L. donovani does not in most areas cause skin lesionsprimary skin lesion (leishmaniomas) appear as papule
formation at site of bite which may be rarely noted
Later become nodular
Frequently, patient may complain of abdominal swelling withoutdefinite illness on PE: massive splenomegaly andhepatomegaly
Acute onset of fever which mimics malarial attack
weight loss, headache, malaise, anorexia, edema, bleedingmucous membrane, lymphadenopathy
malabsorption syndrome and diarrhea are common
Anemia, leukopenia, and thrombocytopenia are common
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Progressive weight loss as disease pursuesits coarse
Body becomes emaciated with theabdomen hugely swollen by the enlargedliver and spleen
Both organs are soft and non-tender
Ascites may occur in advance cases
Grayish pigmentation / darkening of theskin, most marked on the forehead, overthe temples and around the mouth
Death 75-95% in untreated cases (in 2-3yrs)Post kala-azar dermal leishmanoid
- marked by reddish, depigmented nodules that sometimesbecome quite disfiguring
- usually becomes apparent about 1-2 years after inadequatetreatment
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Pathogenesis:
The various species that cause visceral leishmaniasisparasitize cells of the reticuloendothelial system throughoutthe body
The disease is progressive
Most severe form of leishmaniasis
may be fatal if left untreated
Death usually occurs within 2 years due to intercurrentinfections
Proliferation of the RE cells, particularly of the spleen & liver,leads to massive hypertrophy of these organs, which mayreturn to normal size after successful treatment
Mechanism involved in recovery:
Interaction between T lymphocytes and macrophages
Role of humoral factors in human resistance to reinfection
with L. donovani
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Diagnosis:
Clinical picture maybe suggestivedefinitive diagnosis rests on demonstration of amastigote
( blood & tissue smear, bone marrow, lymph nodes, liver,spleen)
Splenic puncture effective method for securingreticuloendothelial cells for study but procedureis risky
Liver puncture safer but not so productive
Bone marrow aspiration diagnostic procedure of choice
Buffy coat films sometimes of valueCulture - NNN medium
Schneiders Drosophila medium
Animal inoculation intraperitoneal inoculation on hamsters
Serological Fluorescent antibody test , ELISA
- sensitive tests but cannot differentiate between
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Treatment:
1. Antimonial compounds:
Sodium stibogluconate (Pentostam)
Meglumine antimonate (Glucantime)
the drug of choice
28 days of intravenous therapy except Sudanese infections
resistant to Antimonials
Pentamidine 2-4mg/kg IM for 10-15 days
2. Liposomal amphotericin-B
- effective in treating Pentosam resistant visceralleishmaniasis
3. Allopurinol 20mg/kg TID in tx of pts with AIDS
4. Interferon gamma enhance the killing of Leishmania
amastigote
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Prevention:
Suppress the reservoir: dogs, rats, gerbils, other smallmammals and rodents
Suppress the Vector: sandfly
Prevent sandfly bites:
House spraying
Public education
Personal protective measures:
Sleeves down Insect repellents
Permethrin treated uniforms
Permethrin treated bed nests
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THE END!Thank You