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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