A comprehensive description of leischmaniasis with its types, transmission, epidemiology, pathogenesis, prevention and control. It also includes details regarding lab diagnosis, disease agent, vector and host.
2. Objectives
At the end of presentation, you will be able to
• Define leishmaniasis
• Typify leishmaniasis
• Manage leishmaniasis
3. Introduction
Leishmaniases are vector-borne diseases caused by
obligate intracellular protozoan parasites from more
than 20 Leishmania species.
There are three main forms of the disease: cutaneous
leishmaniasis (CL), visceral leishmaniasis (VL) or
kala-azar, and muco-cutaneous leishmaniasis (MCL).
Other forms include anthroponotic cutaneous
leishmaniasis, zoonotic cutaneous leishmaniasis &
post kala-azar dermal leishmaniasis (PKDL)
4. The Genus Leishmania includes four major
pathogens:
1. L.donovani complex with 3 species (L.
donovani, L. infantum, and L. chagasi)
2. L. mexicana complex with 3 main species (L.
mexicana, L. amazonensis, and L. venezuelensis)
3. L. tropica
4. L. braziliences
Majority of leishmaniasis are zoonoses while some
forms are considered to be non-zoonotic infections.
5. The different species are morphologically
indistinguishable, but they can be differentiated
by isoenzyme analysis, molecular methods, or
monoclonal antibodies.
Above is the False color SEM micrograph of
Promastigote form Leishmania mexicana as found in
the sand fly midgut. The cell body is shown in orange
and the flagellum is in red. 119 pixels/μm.
8. Vector
Phlebotomus species in the Old World.
Lutzomyia species in the New World.
Only female flies are vector because only they take
blood meals that is required for egg maturation.
9. The main way of parasite transmission is through the bite
of infected female Phlebotomus sand flies. Sand flies
become infected by sucking blood from an infected animal
or person. People might not realize that sand flies are
present because:
They do not make any noise;
They are small: they are only about one third the size of
typical mosquitoes or even smaller;
Their bites might not be noticed (the bites can be painless
or painful).
10. History
In 1903, Leishman identified the parasite and
Donovan described identical organisms in a splenic
puncture.
A devastating epidemic of visceral leishmaniasis
occurred in Sudan from 1984 to 1994
The recent epidemic in south Sudan has caused over
28 300 cases and nearly 900 deaths in the period
from 2009 to 2012.
11. In south America, Brazil has experienced a significant
increase in the number of cases of visceral
leishmaniasis since 1999.
Epidemics of anthroponotic cutaneous leishmaniasis
are of particular concern in Afghanistan, where
decades of war and civil unrest have created
conditions that favor the spread of the disease and
make its control especially difficult. The disease flared
up in 2002, with an estimated 100 000 cases in
Kabul. Because of their low resistance to the disease,
returning refugees and other displaced persons in
Kabul are at higher risk of infection.
12. Life cycle
Leishmaniasis is transmitted by the bite of infected female
Phlebotomus sand flies.
The sand flies inject the infective stage (i.e., promastigotes) from
their proboscis during blood meals.
Promastigotes that reach the puncture wound are phagocytized
by macrophages and other types of mononuclear phagocytic
cells.
Promastigotes transform in these cells into the tissue stage of
the parasite (i.e., amastigotes), which multiply by simple division
and proceed to infect other mononuclear phagocytic cells.
13. Parasite, host, and other factors affect whether the
infection becomes symptomatic and whether
cutaneous or visceral leishmaniasis results.
Sand flies become infected by ingesting infected cells
during blood meals.
In sand flies, amastigotes transform into
promastigotes, develop in the gut and migrate to the
proboscis.
16. Promastigotes
Promastigotes are present 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 1.5 to 1.8 μm
in breadth.
A single nucleus lies in the center. The flagellum is single,
delicate and measures 15-28 μm.
18. Amastigotes
Amastigotes are round in shape & live inside
monocytes, polymorphonuclear leucocytes. They are
2.9-5.9 μm in length.
They are stained well with Giemsa or Wright stain.
In the stained preparation, the cytoplasm appears
pale-blue and nucleus relatively is stained red.
21. Transmission
Leishmania parasites are transmitted through the bite
of infected female sand flies (Phlebotomus species in
Old World & Lutzomyia in New World).
Transmission may occur by contamination of bite
wound or by contact when insect is crushed during
feeding.
Some 70 animal species, including humans, have
been found as natural reservoir hosts
of Leishmania parasites.
23. Sand flies become infected by sucking blood from an
infected animal or person.
After infective meal, sand fly becomes infective in 6 to
9 days.
Transmission of kala-azar has also been recorded by
blood transfusion & through contaminated syringes
and needles.
Congenital transmission (spread from a pregnant
woman to her baby) has been reported.
24. Incubation Period
Incubation period is quite variable. It is generally 1 -3
months; but ranges from 2weeks to 2 years.
25. Pathogenesis
Visceral Leishmaniasis (VL)
Organs of reticuloendothelial system (liver, spleen &
bone marrow) most severely affected.
Reduced bone marrow activity coupled with cellular
destruction in spleen results in anemia, leucopenia &
thrombocytopenia.
This leads to secondary infections & a tendency to
bleed.
Striking splenomegaly is due to proliferation of
macrophages & sequestered RBCs.
26. Cutaneous Leishmaniasis
(CL) & Muco-cutaneous
Leishmaniasis (MCL)
Lesions are confined to skin in CL and to mucous
membranes, cartilages & skin in MCL.
A necrotic ulcer is formed at the bite site due to
granulomatous response.
The lesion has the tendency to become super
infected with bacteria.
27. Epidemiology
Leishmaniasis is found in people in focal areas of more
than 90 countries most of which are developing countries.
It occurs in the tropics, subtropics, and southern Europe.
The ecologic settings range from rain forests to deserts.
90% of all VL: Bangladesh, Brazil, Ethiopia, India,
Nepal and Sudan.
90% of all MCL: Bolivia, Brazil, Peru & Ethiopia.
90% of all CL : Afghanistan, Brazil, Iran and Syria.
28. Annual incidence: 0.7-1.2 million cases of CL
: 0.2-0.4 million cases of VL and over
20,000 deaths annually
Prevalence: 12 million people
Population at risk: 310 million
Leishmaniasis is found on every continent except Australia
and Antarctica.
29. L. tropica & L. Mexicana both causes CL. Former organism
is found in the Old World whereas the latter is found in the
New World (American continents).
In the Old World (the Eastern Hemisphere), CL(Oriental
sore, Delhi boil, Bagdad sore) is found in some parts of
Asia, the Middle East, Africa (particularly in the tropical
region and North Africa, with some cases elsewhere), and
India. It is not found in Australia or the Pacific islands.
In the New World (the Western Hemisphere), CL (chicle
ulcer, bay sore) caused by L.mexicaca is found in Central &
South America. MCL (espundia) is found in Brazil & Central
America.
30. In many geographic areas where leishmaniasis is found in
people, infected people are not needed to maintain the
transmission cycle of the parasite in nature; infected
animals (such as rodents or dogs), along with sand flies,
maintain the cycle. However, in some parts of the world,
infected people are needed to maintain the cycle; this type
of transmission (human—sand fly—human) is called
anthroponotic transmission. In areas with anthroponotic
transmission, effective treatment of individual patients can
help control the spread of the parasite.
31. Kala-azar occurs in three distinct epidemiological
patterns:
1. Mediterranean basin, Middle East, southern
Russia & parts of China, reservoir hosts are primarily
dogs & foxes.
2. Sub-Saharan Africa where rats and small
carnivores are main reservoirs
3. A third pattern is seen in India where humans
appear to be the only reservoir.
32. Leishmaniasis in Pakistan
It is especially present alongside regions bordering
the Afghanistan and cities that have had the
maximum influx of refugees. Moreover, the problem is
especially acute in Baluchistan and Sindh; mainly in
rural areas
Cross boarder movement of infected men is very
common and infected migrant carriers from
Afghanistan are probably the source of outbreak in
Pakistan.
33. In Afghanistan as well as in border areas of Khyber
Pakhtoon Khuwah especially, Waziristan, Kurram
Agency, Parah chinar, Swat, Bannu, Dera Ismail
Khan and Federally Administered area (FATA) several
new species of sand flies were recorded and are
known to be important endemic foci of leishmaniasis
in the region.
Complete data about sand fly fauna of both the
countries and specially vector species is still meager.
35. Systemic leishmaniasis is rarer in Pakistan and
invariably fatal if not treated promptly.
Pakistan has a burden of cutaneous and visceral
leishmaniasis, the muco cutaneous form being almost
nonexistent.
36. In January 2002, a joint assessment mission of the Ministry
of Health and WHO identified 5,000 cases of cutaneous
leishmaniasis in Kurram Agency. The disease first appeared
in refugee camps but quickly reached neighboring villages
where an anthroponotic (person-to-person) transmission
occurred.
As leishmaniasis was previously unknown in the area the
local population had no immunity and there was a sharply
increased risk of a severe epidemic. The rapid response
team identified immediate needs for 15 000 vials of
pentavalent antimonials (first-line drugs) to treat the cases
which were donated by WHO mainly and by Iran.
37. The mission recommended a plan of action to involve
the Ministry of Health, WHO, United Nations High
Commissioner for Refugees (UNHCR) and
nongovernmental organizations in the area to prevent
further transmission by :
1. training of local health workers
2. translation of guidelines into the local languages
3. intensified surveillance
4. vector control activities to.
42. Major risk factors
Socioeconomic conditions: Poverty, poor housing and
domestic sanitary conditions (e.g. lack of waste
management, open sewerage) may increase sand fly
breeding. Human behavior, such as sleeping outside may
increase risk. The use of insecticide-treated bed nets
reduces risk.
Malnutrition: Diets lacking protein-energy, iron, vitamin A
and zinc increase the risk that an infection will progress to
kala-azar.
Population mobility: Often associated with migration and
the movement of non-immune people into areas with
existing transmission cycles.
43. Environmental changes: Leishmaniasis is affected
urbanization, deforestation and settlements into forested
areas.
Climate change: Leishmaniasis is affected by changes in
rainfall, temperature and humidity. Drought, famine and
flood resulting from climate change can lead to massive
displacement and migration of people to areas with
transmission of leishmaniasis, and poor nutrition could
compromise their immunity.
45. Clinical findings
Leishmaniasis encompasses multiple clinical
syndromes, most notably visceral, cutaneous, and
muco cutaneous forms.
Different species can be associated with diverse
clinical manifestations.
Species identification, geographic location, and
immune response of the host can facilitate
clinical management.
46. Initial infections
Similar in all species.
Inoculation of promastigotes.
Inflammation & chemotaxis.
Receptor mediated phagocytosis.
The disease occurs in varying presentations, from the self-limited
and even self-healing cutaneous forms to fatal systemic disease.
Lesions of cutaneous leishmaniasis may occur anywhere on the
body but the most likely sites are the exposed parts. The initial
papule rapidly gives rise to an ulcer.
47. Cutaneous Leishmaniasis
(CL)
The most common form is cutaneous leishmaniasis, which
causes skin sores. The sores typically develop within a few
weeks or months of the sand fly bite. The sores can change
in size and appearance over time. The initial lesions may
start out as papules at bite site. This enlarges slowly to form
multiple satellite nodules. It may end up as ulcers (like a
volcano, with a raised edge and central crater); skin ulcers
might be covered by scab or crust. The sores usually are
painless but can be painful.
49. Visceral Leishmaniasis (VL)
The other main form is visceral leishmaniasis, which
affects several internal organs (usually spleen, liver, and
bone marrow) and can be life threatening. The illness
typically develops within months (sometimes as long as
years) of the sand fly bite. Affected people usually have
intermittent fever, weakness & weight loss.
Hyper pigmentation of skin is seen in light skinned patients
(kala-azar means black sickness). Enlargement (swelling)
of the spleen and liver is present.
50. Certain blood tests are abnormal. For example,
patients usually have low blood counts, including a
low red blood cell count (anemia), low white blood
cell count, and low platelet count. Some patients
develop post kala-azar dermal leishmaniasis. Visceral
leishmaniasis is becoming an important opportunistic
infection in areas where it coexists with HIV.
Untreated severe disease is nearly always fatal as a
result of secondary infections.
54. Muco cutaneous Leishmaniasis
(MCL)
Muco-cutaneous leishmaniasis is an example of
one of the less common forms of leishmaniasis. This
form can be a consequence of infection with some of
the species of the parasite that cause cutaneous
leishmaniasis in parts of Latin America: certain types
of the parasite might spread from the skin and cause
sores in the mucous membranes of the nose (most
common location), mouth, or throat.
55. Begins with a papule at bite site but then metastatic
lesion form usually at muco-cutaneous junction of
nose and mouth. Disfiguring granulomatous
ulcerating lesions destroy nasal cartilage but not
adjacent bone. Death may occur due to secondary
infections.
57. 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.
59. Post kala-azar dermal
leishmaniasis (PKDL)
PKDL is a sequel of visceral leishmaniasis that appears as
macular, papular or nodular rash usually on face, upper
arms, trunks and other parts of the body.
It occurs mainly in East Africa and on the Indian
subcontinent.
It usually appears 6 months to 1 or more years after kala-
azar has apparently been cured, but can occur earlier.
People with PKDL are considered to be a potential source
of kala-azar infection.
61. Leishmania-HIV co-infection
Leishmania–HIV co-infection had been reported from 35
endemic countries with high rates reported from Brazil,
Ethiopia & India.
Leishmania-HIV co-infected people have high a chance of
developing the full-blown clinical disease, and high relapse
and mortality rates. Co-infection with HIV intensifies the
burden of visceral and cutaneous leishmaniasis by causing
severe forms that are more difficult to manage. HIV-infected
people are particularly vulnerable to VL, and VL accelerates
HIV replication and progression to AIDS.
Antiretroviral treatment reduces the development of the
disease, delays relapses and increases the survival of the
co-infected patients.
63. Lab diagnosis
Specimens that may be collected
Splenic aspirate and biopsy
Liver biopsy
Bone marrow (Sternum or iliac crest)
Blood
Dermal scrapings, sections from skin biopsy
64. Microscopy
In the human host, only the amastigotes stage is
seen upon microscopic examination of tissue
specimens. Amastigotes can be visualized with both
Giemsa and hematoxylin and eosin (H&E) stains.
The amastigotes of different Leishmania species are
morphologically indistinguishable. Amastigotes are
ovoid and measure 1-5 micrometers long by 1-2
micrometers wide and are present inside the
macrophages. They have a nucleus in center.
65. Amastigotes in an intact macrophage.
H&E stained skin tissue showing amastigotes.
66. Serology
A very high IgG titer is indicative of infection but not
diagnostic for leishmaniasis.
Various serological tests for leishmaniasis are
1. ELISA
2. Direct agglutination test
3. rk39 dipstick test (based on amastigote epitope
recombinant k 39 protein)
4. Indirect fluorescent antibody test
67. Aldehyde (formol-gel) test
of Napier
1-2 ml serum and 1-2 drops of 40% formalin are added
together.
A positive test is indicated by milky white opacity.
If it occurs in 2-20 minutes, it is said to be strongly positive.
Reaction after 30 minutes is not significant.
Test becomes positive 2-3 months after onset of disease and
reverts to negative 6 months after cure.
Therefore test is good for surveillance, not for diagnosis.
Has low specificity as the test is positive in many other chronic
disease in which albumin to globulin ratio is reversed.
68. Leishmanin (Montenegro) test
Based on skin reaction.
Leishmanin is preparation of 106 per ml washed promastigotes
of leishmania, suspended in 0.5% phenol saline or merthiolate.
0.1 ml leishmanin is injected intradermally on flexor surface of
forearm and examined after 48 to 72 hours.
Induration in noted. Induration of 5 mm or more is considered
positive.
Test is positive 4-6 weeks after onset of CL and MCL.
Usually negative in active phase of kala-azar, but becomes
positive in 75% of cases within 1 year of recovery.
Test is not species specific.
Helps to distinguish immune from non immune subjects
From this information, it may be possible to infer the endemicity
or epidemicity of the infection
69. Culture
Culture media for leishmaniasis are:
SOLID MEDIUM
NNN medium
Evan’s modified Tobie’s medium
LIQUID MEDIA
Schneider’s Drosophila medium
Grace’s insect tissue culture medium
71. Isoenzyme analysis
After isolation parasites can be characterized to the
complex and sometimes to the species level using
isoenzyme analysis, which is the conventional
diagnostic approach for Leishmania species
identification. Diagnostic identification
of Leishmania using this approach may take several
weeks.
72. Hematological findings
Anemia
Leucopenia
ESR is increased
Reversed albumin-globulin ratio
WBC:RBC ration is 1:1500 or even more (normal
ratio is 1:750)
74. Treatment
In general, all clinically manifest cases of VL and MCL
should be treated, whereas not all cases of
cutaneous leishmaniasis require treatment.
General points:
• Improvement of general health
• Balanced diet
• Avoidance of risk factors
75. CL
Therapy of cutaneous leishmaniasis may be indicated to:
1. decrease the risk for mucosal dissemination of disease.
2. accelerate healing of the skin lesions.
3. decrease the risk for relapse of the skin lesions.
4. decrease the local morbidity caused by large or
persistent skin lesions, particularly those on the face or ears
or near joints.
5. decrease the reservoir of infection in geographic areas
where infected persons serve as reservoir hosts (such as in
Kabul, Afghanistan, where transmission is anthroponotic)
76. CL & MCL
Antimony (Pentostam®, Sodium stibogluconate) is
the drug of choice.
• 20 mg/kg body weight IM or IV for 20 days
77. VL
Liposomal amphotericin-B (AmBisome®) is the drug of
choice.
• 1 mg/kg body weight IV infusion daily or alternate day
for 15-20 infusions
Pentostam® is an alternative therapy
• 28 days of therapy is required
78. Conventional amphotericin B deoxycholate is highly effective
therapy for visceral leishmaniasis but generally is more toxic than
liposomal amphotericin B. Immunocompetent patients typically
receive 0.5 to 1.0 mg per kg—either daily or every other day—by
IV infusion—for a total dose of approximately 15 to 20 mg per kg.
Longer courses of therapy may be indicated for some patients
Miltefosine (a phospholipid derivative) can be used for treatment
of cutaneous, mucosal, and visceral leishmaniasis caused by
particular Leishmania species in adults and adolescents at least
12 years of age who weigh at least 30 kg (66 pounds). 100 mg
daily in 2 divided doses for 4 weeks is required.
Miltefosine is contraindicated in pregnant women. Nursing
mothers should be advised not to breastfeed during the
treatment course or for 5 months thereafter.
79. Some medications that might have merit for treating
selected cases of leishmaniasis include
1. parenteral agents: amphotericin B
deoxycholate and pentamidine isethionate, parenteral
formulation of the aminoglycoside paromomycin (11
mg/kg for 21 days)
2. orally administered "azoles"
(ketoconazole, itraconazole, and fluconazole).
Recovery results in permanent immunity.
80. Control
It includes:
Early diagnosis and effective case management:
It reduces the prevalence of the disease and prevents
disabilities and death.
Vector control control: It helps to reduce or interrupt
transmission of disease. It can be done by the use of
various insecticides e.g. DDT.
Reservoir control: Potential reservoirs such as
dogs, rats, gerbils, other small mammals and rodents
should be controlled by methods such as incineration.
81. Education of the community: It should be done with
effective behavioral change interventions with locally
tailored communication strategies. Partnership and
collaboration with various stakeholders and other
vector-borne disease control programmes is critical.
82. Prevention
No vaccines or drugs to prevent infection are
available. The best way for travelers to prevent
infection is to protect themselves from sand fly bites.
To decrease the risk of being bitten, follow these
preventive measures:
Avoid outdoor activities, especially from dusk to dawn,
when sand flies generally are the most active.
83. When outdoors (or in unprotected quarters):
Minimize the amount of exposed (uncovered) skin. To
the extent that is tolerable in the climate, wear long-
sleeved shirts, long pants, and socks; and tuck your
shirt into your pants.
Apply insect repellent to exposed skin and under the
ends of sleeves and pant legs. Follow the instructions
on the label of the repellent.
84. When indoors:
Stay in well-screened or air-conditioned areas.
Keep in mind that sand flies are much smaller than
mosquitoes and therefore can get through smaller holes.
Spray living/sleeping areas with an insecticide to kill
insects.
If you are not sleeping in a well-screened or air-conditioned
area, use a bed net and tuck it under your mattress. If
possible, use a bed net that has been soaked in or sprayed
with an insecticide. The same treatment can be applied to
screens, curtains, sheets, and clothing (clothing should be
retreated after five washings).
85. Vaccine
There is as yet no effective vaccine for prevention of
any form of leishmaniasis.
Several potential vaccines are being developed, but
as of 2015 none are available.
In February 2012, the nonprofit Infectious Disease
Research Institute launched the world’s first
human clinical trial of the visceral leishmaniasis
vaccine in some endemic countries.
