2. Leishmania tropica Complex
Presented By,
Dr. Sourav
MD (Phase-A, Year-1)
Department of Microbiology & Immunology, BSMMU

3. LEISHMANIA
• The genus Leishmania named after Sir William Leishman
who discovered the protozoa causing Kala-Azar
• Primarily it affects the reticuloendothelial system of the host
• The parasite is transmitted by bite of the female sandfly
vector
• Disease caused by Leishmania spp. termed as leishmaniasis

4. Classification of Leishmaniasis
• The protozoa may classified-
 According to clinical picture: i. Visceral leishmaniasis,
ii. Cutaneous leishmaniasis &
iii. Mucocutaneous leishmaniasis
 According to geographical distribution:
i. Old world leishmaniasis and
ii. New world leishmaniasis

5. Leishmaniasis
Old world
Leishmaniasis
Visceral
Leishmaniasis
(Kala-azar)
Cutaneous
Leishmaniasis
Leishmania tropica
complex
New world
Leishmaniasis
Visceral
Leishmaniasis
Cutaneous or
mucocutaneous
Leishmaniasis
Leishmania
donovani

6. Leishmania tropica complex
• It comprises three species:
i. Leishmania tropica
ii. Leishmania major
iii. Leishmania aethiopica
• All these species causes “Old world cutaneous leishmaniasis”
which is also known as ‘Oriental sore’, ‘Delhi boil’, ‘Bagdad boil’ or
‘Aleppo button’

7. History
• The presence of Oriental sore was recorded by the historians since
the period of Emperor Aurungzeb and he himself had been suffering
similar sore thus also termed as Aurangzebi phora
• The parasite was first observed by Cunningham (1885) in the tissues
of a Delhi boil in Calcutta
• Russian military surgeon, Borovsky (1891) gave an accurate
description of its morphology and Luhc (1906) gave the name
Leishmania tropica

8. In 1939-1940, Delhi saw the outbreak of an epidemic which appears to
have involved about 15,000 to 20,000 individuals in Karol Bagh alone.
The first case was reported from a high school.

9. Morphology
Two distinct form:
A. Promastigote form
B. Amastigote form

10. Geographical distribution
Species Geographical distributions
Leishmania tropica
(Oriental sore)
Western India (mainly Rajasthan),
Middle East and Mediterranean coast
Leishmania major Middle East, India, China, North Africa,
and central and western Asia
Leishmania aethiopica Ethiopia, Uganda and Kenya

11. Vectors
Species Vectors
Leishmania tropica Phlebotomus sergenti, P. papatasi, P. chaudaudi
Leishmania major Phlebotomus papatasi, P. duboscqi, P. salehi
Leishmania aethiopica Phlebotomus longipes, P. pedifer

12. Reservoir
 Leishmania tropica: In endemic
areas, dog serve as a reservoir of the
infection.
In desert areas of central Asia,
Gerbils (Rhombomys opimus, a rodent)
are main source of infection.
Fig: Gerbils
Fig: Dog

13. Reservoir contd…
 Leishmania major: In endemic
areas, small mammals such as
gerbils and fat-sand-rats serve as
the main reservoirs.
Fig: Fat-sand-rat

14. Reservoir Contd…
Leishmania aethiopica: Rocky
hyraxes are found to be carries L.
aethiopica in Ethiopia while other
mammals like giant rat, Kenyan
goats, Ethiopian squirrel are also
reported to carry L. aethiopica.
Fig: Rocky hyraxes
Fig: Giant rat

15. Mode of Transmission
•The most common mode of infection is through bite of
sandflies
•May be transmitted from man to man or animal to man by
direct inoculation of amastigotes
•Infection may also occur by autoinoculation

16. Pathogenesis
• The amastigotes are present in the skin, within large
mononuclear cells (monocytes or macrophages), inside
capillary endothelial cells, and also free in the tissues
• They are ingested by sandflies feeding near the skin lesions
• In the midgut of the sand fly, the amastigotes develop into
promastigotes, which replicate profusely

17. Pathogenesis contd…
• These are in turn transmitted to the skin of persons bitten by
sandflies in the skin, the promastigotes are phagocytosed by
mononuclear cells, in which they become amastigotes and
multiply
• However, they remain confined to the skin, without being
transported to the internal organs

19. Pathology of the lesion
• The lesion produced by amastigotes are chronic granuloma
with fibrosis
• In early stage, infiltration of monocytes or macrophages
and later round cells infiltration (lymphocytes or plasma
cells
•It is associated with a marked reduction in the number of
parasites and development of delayed hypersensitivity

20. Clinical Features: Leishmania tropica
• L. tropica causes anthroponotic urban type old world cutaneous
leishmaniasis
• Seen mainly in children in endemic areas and is called as Oriental
sore or Delhi boil
• Incubation: 2 months-3 years
• Usually occurs on face and hands. Begins as papule, becomes
nodular and finally it ulcerates
• The margins of the ulcers are raised, painless and indurated

21. Leishmania tropica Contd…
• There may be satellite lesions
• Lesions may be single or
multiple and vary in size
• Heals spontaneously in about an
year

22. Leishmaniasis Recidivans
•Associated with L. tropica
•Small, non-ulcerating lesions begin to
appear, mainly on the margins of
healed lesions, and continue to
expand the limits of the original scar
•CMI is intact and skin test is positive

23. Clinical Features: Leishmania major
• Leishmania major causes zoonotic rural type old world
cutaneous leishmaniasis
• This causes moist, inflamed, often multiple ulcers
• Incubation period: Less than 4 months
• Heals more rapidly than L. tropica

24. Clinical Features: Leishmania aethiopica
• Causes “Diffuse Cutaneous Leishmaniasis”
• It is a rare form of disease, where nodular lesions although
restricted to skin are disseminated on the face and
extremities from initial localized papule
• Low humoral as well as cell mediated immunity
• This condition is similar to that of lepromatous leprosy
• Difficult to treat

25. Nodules on face in Diffuse
Cutaneous Leishmaniasis
Nodular diffuse cutaneous leishmaniasis lesions
with minimal open ulcerations in the extremities

26. Laboratory diagnosis
Specimen collection:
 Scraping, aspirates or biopsy material from the lesion may be
taken as specimen
 If the patient has multiple lesions, specimens should be collected
from the more recent or active lesions
 Lesions should be thoroughly cleaned with 70% alcohol, and
necrotic debris should be removed to prevent the risk of bacterial
and/or fungal contamination

27. Specimen collection
 Specimen should be taken from the advancing margin of the
lesion
 The specimen of choice would be a collection of several punch
biopsy specimens taken from the most active lesion areas
 Multiple slides should be prepared for examination
 Specimen should be taken from the advancing margin of the
lesion

28. Specimen collection
 The specimen of choice would be a collection of several punch
biopsy specimens taken from the most active lesion areas
 Fine-needle aspiration can also be performed with a sterile
syringe containing sterile saline (0.1 ml)
 The needle is inserted into the outer border of the lesion and
rotated several times, after which saline is injected and tissue
fluid is aspirated back into the needle

29. A. Microscopy
• Smear is made from the material obtained from the indurated
edge of nodule or sore and stained by Giemsa or Leishman stain
• Amastigotes are found inside the macrophages
• Definitive diagnosis is made by demonstration of amastigote in
the smear collected from the lesion

30. B. Culture
• Aspiration from the ulcers can be cultured in NNN medium for
the isolation of promastigote forms
• Aseptic techniques for collection of specimen is required for
culture as the media also favour bacterial growth
•Cultures should be checked weekly for 4 weeks before they are
declared negative

31. C. Skin test
• The Leishmanin skin test (Montenegro test) is useful for
epidemiologic population surveys
• Indicates delayed hypersensitivity reaction to the parasite
• Positive Leishmanin test: Induration ≥5mm within 48
hours
• Negative in diffuse cutaneous leishmaniasis

32. Fig: Following intradermal application of the solution, the result
evaluated within 48 hours with a ballpoint pen, being positive as the
papule formed is equal or greater than 5mm

33. Animal Inoculation
• Animal inoculation can be helpful when only a small
number of organisms is present
• Golden hamsters are inoculated intranasally
• It takes several weeks to become positive

34. D. Serologic Tests
• Immunofluorescence antibody test may be done but this
has of limited value as the patient shows no detectable
levels of circulating antibodies

35. Treatment
 Treatment of choice: Pentavalent antimonial (SbV) preparations
(eg. Sodium stibogluconate or Meglumine antimoniate)
 Antimony-resistant diffuse CL can be treated with Pentamidine
 Topical treatment consists of a paste of 10% charcoal in sulfuric
acid or liquid nitrogen
 Thermotherapy may be effective

36. Prevention
• Control of sandfly population by insecticides and sanitation
measures
• Personal protection by use of protective clothing and use
of insect repellants
• Elimination of mammalian reservoir
• A vaccine has been developed but, the clinical trials are still
ongoing

37. Features L. tropica L. major L. aethiopica
Disease type CL, LR CL CL, DCL
Humoral antibodies Variables Present Variables
Delayed hypersensitivity to
Leishmanin
Present
Strong for LR
Present Weak
Absent for DCL
Parasite present in Clinical
specimen
Present but few in
LR
Present Present and abundant
in DCL
Self cure Yes
Slowly in LR
Rapidly Slowly but DCL is
difficult to cure
Recommended biopsy specimen Skin Skin Skin
Differentiating features between species
CL: Cutaneous leishmaniasis; LR: Leishmaniasis Recidivans; DCL: Diffuse cutaneous leishmaniasis

38. Questions?
1. What is Leishmania tropica complex? Name the
organisms.
2. Explain the pathogenesis of Leishmania tropica.
3. Short note: Oriental sore