Leishmaniasis - By Dr/ Faiz Al-Khawlani

Medical
Parasitology
د/ فایز الخولاني
The Most Common •
Parasitic Infections
In Yemen

Tissue protozoa 2015-2014 Leishmaniasis
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Leishmaniasis
Leishmaniasis: is a vector-borne disease that transmitted by sandflies
and caused by obligate intracellular protozoa of the genus Leishmania.
About 21 of 30 species cause human infection. The different species are
morphologically indistinguishable, but they can be differentiated by
isoenzyme analysis, molecular methods, or monoclonal antibodies. The
following table summarizes the clinical diseases caused by the most
important Leishmania species.
Disease
Leishmania species
Visceral
leishmaniasis
L. donovani L. infantum L. chagasi
Cutaneous
leishmaniasis
L. tropica L. major L. aethiopica L. mexicana
Diffuse-cutaneous
leishmaniasis
(DCL)
L. aethiopica L. mexicana L. mazonensis
Muco-cutaneous
leishmaniasis
(MCL
L. braziliensis L. panamensis

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Epidemiology and Distribution
Leishmaniasis is endemic in 88 countries with an estimated 350 million
people at risk of infection. The overall prevalence of the leishmaniasis
estimated to be at 12 million cases with 0.5 million new visceral
leishmaniasis cases per year and 1.0–1.5 million new cutaneous
leishmaniasis cases per year. More than 90% of visceral leishmaniasis
occurs in Sudan, Bangladesh, Nepal, Brazil and India, and more than
90% of cutaneous leishmaniasis in Brazil, Peru, Afghanistan, Syria, Iran,
Yemen and Saudi Arabia. In recent years, there have been major
epidemics of visceral leishmaniasis in southern Sudan, eastern India,
Bangladesh, and Brazil. Increased infections and the spread of
leishmaniasis is related to environmental and behavioral changes and
development, conflict and war, bringing non-immune people into closer
contact with vectors and reservoir hosts.
Transmission and life cycle
□ Leishmania is mostly zoonotic (transmitted to humans from animals),
and humans become infected only when accidentally exposed to the
natural transmission cycle.
□ However, humans are the sole reservoir hosts when the transmission
occurs from human to human through the sand fly vector.

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□ Leishmania species are transmitted by the bite of an infected female
sandfly, belonging to the genus Phlebotomus in Africa, Asia and
Europe, and the genus Lutzomyia in the Americas.
□ About 30 species of sandflies act as vectors, infecting humans and
animal reservoir hosts.
Pattern of transmission
□ Human-to-human transmission: man is the only source and
reservoir of infection.
□ Dog-to-human transmission: The infection source is domestic dogs
and some rodents, which acts as a reservoir host.
Classification of leishmaniasis according to the location
Leishmaniasis
OLD WORLD
(Africa, Asia, Europe)
Leishmania species
NEW WORLD
(South America and Central
America)
Leishmania species
Visceral leishmaniasis
L. donovani
L. infantum
L. chagasi
Cutaneous leishmaniasis
L. tropica
L. major
L. aethiopica
L. guyanensis
L. amazonensis
L. Mexicana
Diffuse cutaneous leishmaniasis L. aethiopica
L. Mexicana
L. amazonensis
Mucocutaneous leishmaniasis L. braziliensis
L. panamensis

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Sandfly vectors
The feeding, breeding and flight habits of sandflies are species specific.
Most sandflies feed mainly on plant juices, but female flies also require
blood meals for egg development. Most species feed at night, dusk or
dawn.
Morphology
The parasite exists in two forms:
1. Amastigote
2. Promastigote
Amastigote
Amastigotes are round in man and other vertebrate hosts. Amastigotes
live inside monocytes, polymorphonuclear leucocytes. They are small,
round to oval bodies measuring 2.9-5.9 μm in length (Fig below). They
are stained well with Giemsa’ or Wright’ stain. In the stained preparation,
the cytoplasm appears pale-blue and surrounded by a limiting membrane.
The nucleus relatively is large and stained red. The kinetoplast lies at
right angle to the nucleus. It is slender, rod-shaped and is stained deep
red. Axoneme arises from the kinetoplast and extends to margin of the
body. Vacuole, which is a clear unstained space, lies alongside the
axoneme.

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Leishmania. Amastigote
Promastigote
Promastigotes are excited in the digestive tract of sand fly (vector) and in
the culture media. The fully developed promastigotes are long, slender
and spindle-shaped. They measure 14.3 to 20 μm in length and 1.5to 1.8
μm in breadth. A single nucleus lies at the center. The kinetoplast lies
transversely near the anterior end. The flagellum is single, delicate and
measures15-28 um. With Leishman stain, cytoplasm appears blue, the
nucleus pink and the kinetoplast blight red (Figure below).

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Fig. ( ) Leishmania species Promastigote
Life cycle in man
 The life cycle of Leishmania species is summarized in Fig below.
 It consists of two forms: amastigote, which presents in the human
macrophages and promastigote, which presents in the sandfly and
culture media.
 Life cycle of Leishmania species involves two hosts: human host
(vertebrate host) and insect host (vector host, invertebrate host).
 Because it is not identified the sexual stages of the parasite, the
definitive host is not recognized yet.
 The life cycle begins with injection the infective stage metacyclic
promastigote into the human host at the time of taking blood meal by
the female sandfly.
 The skin macrophages phagocytize the promastigotes by a process of
phagocytosis then transform into intracellular forms called
amastigotes.

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 Amstigotes multiply within skin macrophages (in case of cutaneous
leishmaniasis), liberate from the macrophages, and infect new cells.
 In visceral leishmaniasis, the amastigotes multiply in the
macrophages of the spleen, liver, bone marrow and lymph glands
of the reticuloendothelial system.
 Blood monocytes are also infected.
Life cycle in sandfly
 When intracellular and free amastigotes are ingested by a female
sandfly the life cycle is continued
 After about 72 hours, the amastigotes become flagellated
promastigotes in the midgut of the sandfly.
 They multiply and fill the lumen of the gut.
 After 14–18 days (depending on species), the promastigotes move
forward to the head and mouth-parts of the sandfly.
Sandfly the leishmaniasis vector

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Injection of metacyclic promastigote the infective stage into the human skin
Life cycle of Leishmania

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Symptoms of Visceral leishmaniasis (VL)
□ This is the most severe form of leishmaniasis.
□ It is caused by L. donovani and L. infantum in the old world and L.
chagasi in the new world.
□ In the endemic areas, the disease is more chronic with young adults
and children being more commonly infected.
□ In epidemics, all age groups are susceptible (except those with
acquired immunity), and the disease is often acute.
□ Without treatment, VL is usually fatal.
□ Symptoms in acute VL, there is splenomegaly, high undulating fever
with two peaks in the day, chills, profuse sweating, weight loss,
fatigue, anaemia, and leucopenia.
□ Symptoms in chronic VL include irregular fever, massive
splenomegaly, hepatomegaly, and/or lymphadenopathy, marked loss
of weight with wasting, diarrhea, low white cell and platelet counts,
and anaemia.
□ The local Indian name for VL, kala-azar (meaning black sickness or
black fever) is a reference to the darken color of the infected patients.
□ Malnutrition and other infections increase the risk of developing
symptomatic VL.

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Massive splenomegaly in VL
Post kala-azar dermal leishmaniasis (PKDL)
□ In India and occasionally in Africa, a cutaneous form of leishmaniasis
can occur about 2 years after treatment and recovery from visceral
leishmaniasis.
□ This is referred to as post kala-azar dermal leishmaniasis and
affects about 20% of patients in India.
□ Hypopigmented and raised erythematous patches appear on the face,
trunk of the body, and limbs.
□ These may develop into nodules and resemble those of lepromatous
leprosy, fungal infections or other skin disorders.
□ Occasionally there is ulceration of the lips and tongue.
□ Amastigotes are present in the papules and nodules.

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Figure ( ) PKDL in sudan Papular and nodular PKDL
Figure ( ) PKDL affecting the earlobe
Figure ( ) PKDL: macular lesions, some are confluent.

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Immunity
□ Absence of Gamma Interferon IFN ᵧ and Interleukin 2 during Active
Visceral Leishmaniasis
□ Inhibition of parasitic Ag presentation by the antigen presenting cells
(APCs)-macrophage because lysis of intracellular amastigote is
blocked.
□ Leishmania proamastigote has surface inhibiter molecules called
lipophosphoglycan (LPG) that inhibits the toxic effect of macrophage
nitric oxide.
□ Nitric oxide or nitrogen mediators are a potent toxic oxidant that
destroys intracellular pathogens however, promastigote of leishmania
parasite has the ability of inhibition the nitric oxide-dependent killing
mechanism of the macrophage.
□ Because the acidic pH is an environment suitable for living and
multiplication of the amastigote, thus lysis of intra-phagosome
amstigote does not achieved by the macrophage lysosomes.
□ As a result, rupture of parasitized phagocyte occurs and releasing of
amastigotes that in turn infects other macrophages.
□ T lymphocytes are not activated unless recognizes the pathogen Ag
which must be expressed on the surface macrophage.

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□ Macrophages have the key role in an initiating the cell-mediated
immune response, and one of some immune cells that act as an
antigen presenting cells.
□ In normal phagocytosis, the phagocyte lysosomes destructs the
intracellular pathogen into small peptides, these peptides are then
expressed on the macrophage surface via the Major
Histocompatibility molecules class 1(MHC molecules).
□ After an antigen presenting, macrophage release a cytokines
molecules called Il-2 and INF ᵧ, which activate T lymphocytes.
□ The consequences of T lymphocytes activation is the direct killing of
infected cells and controlling the disease prognosis.

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Illustration of leishmania parasite during invasion of macrophage

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Development of the immune response to protozoan and helminth infection

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Cutaneous leishmaniasis (CL)
□ Cutaneous leishmaniasis is a potentially severe and disfiguring
disease in some people.
□ The clinical forms of CL vary according to the species of parasite,
region, and immune response of the patient.
□ People with cutaneous leishmaniasis have one or several long-lasting
lesions on the skin, usually without fever or general symptoms.
□ New cases are emerging in areas previously free of the disease.
□ Over 100 000 new cases of cutaneous leishmaniasis are reported
annually to WHO by countries in the Region, but the actual incidence
is estimated to be three to five times higher since many patients never

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seek medical attention and not all patients with a diagnosis of
cutaneous leishmaniasis are reported to health authorities.
Old world cutaneous leishmaniasis (CL)
Cutaneous leishmaniasis caused by L. tropica
□ Infection is often referred to as dry urban oriental sore.
□ Dry painless ulcers 25–70 mm in diameter are produced which are
self-healing usually after 1–2 years but often leave disfiguring scars.
□ The patient acquires immune to reinfection.
□ Rarely, multiple unhealed lesions may develop, often on the face.
□ It can last many years and is difficult to treat; this condition is known
as leishmaniasis recidivans (LR).
□ Untreated LR may leads to destruction and disfiguration of the
infected parts.
Initial brownish nodule of dry, urban type of cutaneous leishmaniasis

Tissue protozoa Leishmaniasi2014-2015 s
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Plaque lesion of dry, urban type of cutaneous leishmaniasis
Dry, urban and anthroponotic type of cutaneous leishmaniasis
Leishmaniasis recidivans due to (L. tropica) from Morocco.Note the healed scar
from which new lesions develop.

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Chronic cutaneous leishmanaisis of face with areas of scarring and reactivation
of disease (Leishmaniasis recidivans)
Leishmaniasis recidivans due to (L. tropica) from Afghanistan.
Note the healed scars from which new lesions develop.
Cutaneous leishmaniasis caused by L. major
□ Infection is often referred to as wet oriental sore.
□ The early papule is often inflamed and resembles a boil of 5–10 mm
in diameter which rapidly develops into a large uneven ulcer which is
self-healing in as little as 3–6 months.
□ Multiple lesions may occur in non-immune persons.
□ L. major infections show permanent immunity against reinfection.

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Wet ulcer in CL
Cutaneous leishmaniasis caused by L. aethiopica
□ A cutaneous lesion that is similar to typical oriental sore with healing
in 1–3 years.
□ Localized cutaneous lesions may spread to involve large cutaneous
area, forming a nodules often associated with scaling. This form is
known as diffuse cutaneous leishmaniasis.
□ The patients who have diffuse cutaneous leishmaniasis are more
likely of little or no cell -mediated immunity against the parasite.
Chronic localized cutaneous leishmanisis of face Non-healing chronic
cutaneous leishmaniasis”

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Diffuse cutaneous leishmaniasis (DCL)
□ Both L. aethiopica (Old World) and L. amazonensis (New World) are
the causes of diffuse cutaneous leishmaniasis.
□ Skin lesions develop over a large area of the body.
□ The lesions on the eyebrows, nose and ears resemble those of
lepromatous leprosy.
□ At first, the lesions are smooth, and firm.
□ Later they become scaly and rough.
□ The nodules contain large numbers of amastigotes.
□ The lesions do not heal spontaneously and this is an incurable
condition characterized by the formation of disfiguring nodules over
the surface of the body.
□ DCL caused by L. amazonensis is resistant to treatment.
□ DCL caused by L. aethiopica, relapses occur after treatment.
Diffuse cutaneous leishmaniasis- Venezuela

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Diffuse Cutaneous Leishmaniasis (DCL) from Ethiopia. The patient originating
from the Highlands where CL and not VL is endemic; there is no previous history
of VL. Leishmania parasites were found in a skin scraping.
Mucocutaneous leishmaniasis (MCL)
□ In New World, both L. braziliensis and L. panamensis can cause
Mucocutaneous leishmaniasis (MCL).
□ In south America Mucocutaneous leishmaniasis (MCL) known as,
‘espundia’.
□ Rarely MCL is caused by L. tropica and L. aethiopica in the old
world.
□ MCL is the most severe and destructive form of cutaneous
leishmaniasis in South America.
□ Lesions are similar in development to those of oriental sore and the
resulting ulcers may become very large and long lasting.

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□ Disfiguration is extreme with complete destruction of the infected
part, such as nasal septum if the nose is the primary lesion and
damage to the tissues of the lips and ear cartilage.
□ Mucosal lesions do not heal spontaneously and severe secondary
bacterial infections can occur.
□ A Sudanese form of MCL is referred to as oro-nasal leishmaniasis.
Mucocutaneous leishmaniasis (MCL)
Treatment of Leishmaniasis
 Most sores will heal spontaneously within one year.
 Treatment of cutaneous and muco-cutaneous leishmaniasis is the
same while the latter needs more intensive treatment due to the more
severe and destructive complications.

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Pentavalent antimony:
Pentostam
 Unfortunately, some cases of leishmaniasis may treated by topical
steroid preparation. This changes the clinical picture, deteriorates the
lesion, which becomes later more chronic and decreases its response
to the specific medications.
 For adults, we give 6 cc of Pentostam I.M. daily for 10 days.
 This usually gives very good results, causing rapid healing of the
ulcers.
 The dose is adjusted according to the age (20 mg/kg of body weight).
Neostibosan
 Neostibosan (Bayer): is also an effective medication.
 The daily dose is 5mg/kg body weight .
 A dose of 200-300 mg. can be given for older children and adults
daily for 16 days is proved to be effective.
 Patients with diffuse cutaneous leishmaniasis require treatment for a
longer time.
Liposomal amphotericin-B (AmBisome®)
 Is the drug of choice for VL.
 It is given in a dose of 3 mg/kg per day on days 1-5, day 14 and day
21.

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Laboratory Diagnosis
Diagnosis of visceral leishmaniasis
The laboratory diagnosis of visceral leishmaniasis (VL) is by:
Finding amastigotes in:
o material aspirated from the spleen, bone marrow or an
enlarged lymph node,– nasal secretion.
o peripheral blood monocytes and less commonly in
neutrophils (buffy coat preparations).
Culturing aspirates and peripheral blood and examining cultures
for promastigotes.
Other tests
Formol gel (aldehyde) test. This is a non-specific screening test which
detects marked increases in IgG. Large amounts of polyclonal non-specific
immunoglobulin are produced by patients with active VL.
Haematological investigations including:
o measurement of haemoglobin,
o total and differential white cell (leukocyte) count,
o platelet (thrombocyte) count.
Detection of anti-leishmanial antibody
□ In visceral leishmaniasis, specific antibody as well as non-specific
polyclonal Ig G and Ig M are produced.

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□ Several techniques have been developed to detect and measure
specific anti-leishmanial antibodies in patients’ sera.
□ Those being used in district laboratories and field surveys include:
Direct agglutination test (DAT) or rK39 dipstick to detect anti-rK39
antibody.
Diagnosis of cutaneous and mucocutaneous Leishmaniasis
The laboratory diagnosis of CL and MCL is by:
 Detecting amastigotes in smears taken from infected ulcers or
nodules. In MCL, the parasites are scanty and difficult to find in
smears.
 Culturing ulcer material and examining cultures for promastigotes.
Serological diagnosis of CL and MCL
 Because of the poor antibody response in CL, serological tests are
of little value in diagnosis.
Leishmanin skin test (Montenegro test)
 It is a delayed hypersensitivity skin test. In this test, 0.2ml of
Leishmania antigen (containing 100,000,000 promastigotes of L.
donovani in l ml of 0.5% phenol saline) is injected intradermally.
The test is read after 48 to 72 hours.
 A positive test shows an area of erythema and induration of 5 mm
in diameter or larger, which heals in 14-25 days.

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 Positive reaction indicates prior exposure to leishmanial parasites.
 In kala-azar, the skin test becomes positive usually only 6 to 8
weeks after cure from the disease, it is negative in active cases.
Culture of ulcer material
 Culture is of value when cutaneous leishmaniasis is suspected and
parasites cannot be found in smears.
Measures to prevent and control leishmaniasis
□ Early detection and treatment of infected persons, especially in
areas where humans are the only or important reservoirs of infection.
□ Personal protection from sandfly bites by:
Using insect repellants, although in hot and humid conditions they are of
limited use due to profuse sweating.
Avoiding endemic areas especially at times when sandflies are most
active.
Use of insecticide impregnated bed nets and curtains.
□ Vector control by the use of light traps, sticky paper traps, or
residual insecticide spraying of houses and farm buildings where this
is practical, or alternatively using insecticide paints in a slow-release
emulsifiable solution.
□ Destruction of stray dogs and infected domestic dogs in areas where
dogs are the main reservoir hosts.

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□ Elimination and control of rodents in areas where these are sources
of human infections.
Leishmania amastigotes in Giemsa stained skin slit smear.
Leishmania amastigotes in monocyte in a Giemsa stained blood film.
Giemsa stained amastigotes of L.donovani. Right:
As seen in bone marrow. Left: As seen in splenic aspirate.

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Formol gel test showing positive (+) and negative ( - ) reactions.

Leishmaniasis - By Dr/ Faiz Al-Khawlani

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