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LEISHMANIA. Classification Leishmania parasites for humans have been Classified into 2 broad groups: A) Causing Visceral Leishmaniasis (VL) The L.donovani complex infecting internal organs (Liver, Spleen, Bone Marrow) causing Visceral

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Leishmania parasites for humans have been Classified into 2 broad groups:

A) Causing Visceral Leishmaniasis (VL)

The L.donovani complex infecting internal organs

(Liver, Spleen, Bone Marrow) causing Visceral


B) Causing Cutaneous & / or Muco cutaneous

Leishmaniasis (CL)

1. L.tropica – (Old World CL)

2. L.mexicana complex, L.braziliensis complex – (New world or American CL)

Morphology the parasite exists in 2 stages
Morphology: The parasite exists in 2 stages

  • Amastigote stage (formerly called Leishmanial forms)

  • - Occurs in Man

  • 2) Promastigote Stage (formerly called Leptomonad form)

  • - Occurs in

  • - Gut of Insect (Sand Fly)

  • - Artificial culture

Amastigote stage aflagellate stage
Amastigote Stage : (Aflagellate Stage)

Parasite → Resides in cells of RE system of vertebrate hosts (Man, Dog & Hamster)


  • Shape & Size-Round/Oval, 2 – 4 µm along longitudinal axis.

  • Nucleus- 1µm – diameter, Oval/Round in shape.

  • Kinetoplast- Situated at right angles to Nucleus contains DNA containing body & a mitochondrial structure.

  • Axoneme- Delicate filament extending from kinetoplast to margin of body.

  • Vacuole- Clear, unstained space along Axoneme.

Promastigote stage flagellar stage
Promastigote Stage : Flagellar Stage

Parasite →

Cultures & Insect vectors (Sand Flies)


  • Size & Shape-

  • Early ones- Short Oval/Pear shaped bodies, 5 – 10µm in length and 2 – 3µm in breadth.

  • Fully developed- Long, slender spindle shaped bodies, 5 – 20µm in length and 1-2µm in breadth

  • Kinetoplast - Transversely near anterior end.

  • Vacuole- Eosinophilic, in front of kinetoplast over which root of flagellum runs.

  • Flagellum-May be of same length as body or longer.

  • Nucleus- Central


  • Cultured in a medium composed of 2 parts of Salt Agar & 1 part defibrinated Rabbit’s Blood.

  • Material for culture → inoculated at 22ºC-24ºC

  • Presence of Ascorbic acid & hematin favours growth

  • Medium- introduced by Navy & Neal, later modified by Nicolle. So named NNN medium

  • Temp: 37ºC for 32 days

  • Susceptible Animal: Dog

Reservoirs of infection
Reservoirs of Infection

Dog in – Mediterranean areas



Method of Transmission

Man to Man → Sand Fly of genera Phlebotomus & Lutzomyia

Leishmaniasis does not exist in India hence in India man is only source of infection

Kala azar

Visceral leishmaniasis was 1st characterised in India, where it was known under the names

•Kala-Azar (Black Sickness)

•Dum Dum fence

•Burdwan fever

•Tropical Splenomegaly

Incubation Period: 3 – 6 months.

Clinical features

  • Pyrexia

  • Splenic Enlargement

  • Liver Enlargement

  • Lymphadenopathy

Lab diagnosis of Kala Azar cutaneous Lesion may appear

Direct evidence

Indirect evidence

Demonstration of L.donovani


Peripheral Blood

Blood Culture

Material obtained by

  • Amastigote form

  • Promastigote



Sternal/Iliac crest


Lymph node


Aldehyde test

Antimony test

Complement Fixation test

Leishmanin test : cutaneous Lesion may appearKilled culture injected intradermally  + ve reaction produced in Kala azar cases 6 – 8 wks after recovery & represents a delayed hypersensitivity reaction accompanied by CMI

Alders test : Development of promastigote of Leishmania in Locke’s serum agar can be inhibited by a specific immune serum but can take place in heterologous serum

PROPHYLAXIS cutaneous Lesion may appear

  • Attack on parasite

  • Attack on the vector

  • Personal prophylaxis

Dermal leishmanoid post kala azar dermal leishmaniasis

A type of non ulcerative cutaneous lesion prevalent in endemic areas of Kala azar in India (Bengal, Madras & Assam)

Clinical manifestations

- Deep pigmented macules

- Erythematous patches (Butterfly erythema)

- Yellow pink nodules


L.Tropica cutaneous Lesion may appear

[parasite causing Cutaneous Leishmaniasis]

Geographical Distribution


Central & Western India (drier pats)

Central Africa


Habitat: Inside Clasmatocytes (cells of RE sys) of skin

Morphology: Amastigote form → in Man

Promastigote form → in Cultures & Sandflies

  • Cultivation cutaneous Lesion may appear: in NNN -Novy, Mac.Neal,Nicolle medium

  • Susceptible Animals: In Mice, intraperitoneal inoculation produces Visceral infection

  • Pathology

  • Nature of lesion is characterised by a chronic infective Granuloma with fibrosis.

  • In early stage, proliferation of the cells of RE system (Monocytes/Macrophages) forms the primary reaction, inside which parasites are found in large numbers

  • Later, round cell infiltration associated with a marked reduction in number of parasites & development of a delayed hypersensitive skin reaction (Leishmanin reaction) occur

CLINICAL FEATURES cutaneous Lesion may appear

  • Oriental Sore (tropical sore) / Delhi boil (slow healing open ulcer/sore)

  • It ulcerates having clean cut margin with a railed indurated edge, surrounded by red areola

  • Core has tendency to heal spontaneously but slowly, taking 6 months. The ulcer is filled up by granulomatous tissues, a depressed white scar is often left

LAB DIAGNOSIS cutaneous Lesion may appear

  • Leishmanin/Skin test is positive in cases of Oriental sore

  • Prophylaxis

  • Elimination of reservoir hosts

  • Control of Sandflies

  • Individual protection from Sandfly bite

  • Prophylactic immunisation with a culture of L.tropica

CUTANEOUS LEISHMANIASIS cutaneous Lesion may appear

New World Disease

Common in Algeria, Iran, Iraq, Saudi Arabia, Syria, Peru, Brazil, Afganistan

Etiological agents: L.mexicana complex

Old World Disease


MUCOSAL LEISHMANIASIS cutaneous Lesion may appear

  • Rare

  • Infection of Naso-oropharyngeal mucosa

  • Clinical Manifestations

  • Persistant unusual nasal symptoms (Epistaxis) with Erythema, Edema of Nasal mucosa

  • Ulceration

  • Naso-oropharyngeal destruction

TRYPANOSOMA cutaneous Lesion may appear

INTRODUCTION cutaneous Lesion may appear

  • These type of flagellates live in the blood or tissue of man or other animals.

Generic character
GENERIC CHARACTER cutaneous Lesion may appear

  • These exits as trypomastigotes in vertebrate hosts (man or animals).

  • They pass their life cycle in two hosts :

  • Vertebrate

  • Insect

  • While developing inside the insect host, they pass through the stages of amastigote , promastigote, epimastigote & metacyclic form of trypomastigote.

  • Multiplication can takes place in any of these developmental stages.

  • Transmission is effected from one vertebrate to another by blood – sucking insects.

  • Classification
    CLASSIFICATION cutaneous Lesion may appear

    • It causes African trypanosomiasis in man & nagna in domestic animals.


    HABITAT cutaneous Lesion may appear

    • T. brucei is essentially a parasite of connective tissues, where it multiplies readily. It invades the regional lymph nodes through the lymphatics & also invades the blood stream causing Parasitaemia. It finally localises in the brain.

      MORPHOLOGY : T. brucei exits in vertebrate host as a trypomastigoteform.

    • It is an elogated rather flattened spindle - shaped organism with a blunted posterior end & a finely pointed anterior end.

    • The nucleus is large, oval & central in position

    • The kinetoplast is small & present in the posterior end of the body.

    • The flagellum starts near the posterior end, curves around the body & continues beyond the anterior end as a free flagellum.

    Staining reaction
    STAINING REACTION cutaneous Lesion may appear

    • When stained with Leishman or some other modifications of romanowsky stain: a) The cytoplasm & the undulating membrane appear pale blue

      b) The nucleus is reddish purple in colour

      c) The kinetoplast & the flagellum dark red.


      It has been cultivated in a medium of Ringer’s solution with sodium chloride, Tyrode’s solution & citrated human blood.


    • Laboratory animals like mice, rats and guiuea pigs are generally inoculated for demonstrating the tryopmastigotes when they are scanty or difficult to find in the peripheral blood of the man.

    Life cycle
    LIFE CYCLE cutaneous Lesion may appear

    • T. brucei passes its life cycle in two different hosts:

    • The vertebrate hosts are man, and domestic amimals.

    • The insect hosts are several species of the tsetse fly.

    Transmitting agents reservoir of infection

    • The animal strain of T. brucei is transmitted by Glossinamorsitans amongst the wild game and domestic animals.


      1) Mode of infection: By the bite of the infective tsetse fly Glossina. Some trypomastigotes may enter the blood stream but majority remains entangled in the tissue spaces. The presence of trypomastigotes in the tissue spaces excites host’s response in two ways:

    • By producing large amount of non-specific immunoglobulin which are not able sensitising the antigen.

    • By the action of macrophages. The neutrophils take little interest in the defence.

    2) cutaneous Lesion may appear Pathogenic lesion:

    • There is severe damage of the perivascular connective tissue.

    • The lesions are found mainly in the lymph nodes & central nervous system.

      Laboratory diagnosis:

    • This is established y demonstrating the following:

    • Peripheral blood

    • Bone marrow obtained by sternal puncture

    • Juice aspirated from the swollen lymph nodes

    • The cerebrospinal fluid obtained by lumbar puncture.

    TRYPANOSOMA CRUZI cutaneous Lesion may appear

    • GEOGRAPHICAL DISTRIBUTION: Central & South America.

    • HABITAT: A parasite of musculra & nervous tissue & also of the reticular endothelial system.

    MORPHOLOGY cutaneous Lesion may appear

    Two main morphological types are found in human host:

    • A) Trypomastigote form: In dried and stained film it appaers to be C or U shaped.

    • It measures 20 micrometer in length,has central nucleus and a large, oval kinetoplast situated at the posterior end.

    • B) Amastigote form: The amastigote forms are round or oval bodies, measuring 2 to 4 micrometer in diameter, having nucleus & a kinetoplast.

    Staining reaction1
    STAINING REACTION cutaneous Lesion may appear

    • When stained with Leishman or some other modifications of romanowsky stain: a) The cytoplasm & the undulating membrane appear pale blue

      b) The nucleus is reddish purple in colour

      c) The kinetoplast & the flagellum dark red.

    IMMUNOLOGY cutaneous Lesion may appear

    • Serum antibodies develop in T. cruzi infection but as the parasite continues to grow, so they are not exposed to the action of these antibodies.

    Life cycle of t cruzi
    LIFE CYCLE OF T. CRUZI cutaneous Lesion may appear

    Reservoir hosts
    RESERVOIR HOSTS cutaneous Lesion may appear

    • These are Armadillos & opossum.

    • Man is the secondary host.


    • By microscopic examination of a stained blood film.

    • By inoculating a guinea pig with patient’s blood.

    • By a specific complement fixation test with antigen obtained from culture of T. cruzi.