World Health Organization, Data and Statistics
Fact Sheet
Visceral Leishmaniasis / Kala‐azar
Key facts
Visceral leishmaniasis, commonly known as kala‐azar, is a parasitic disease
caused by Leishmania protozoan and transmitted by sandflies.
It is one of neglected tropical diseases which can be fatal if not treated, with an
estimated 500,000 cases occur annually.
Symptoms include prolonged fever, weight loss, swelling of liver and spleen and
anaemia.
There are new tools available for diagnosis and treatment of VL, including rapid
tests and single dose treatment.
Vector control, surveillance and research are other component of control
strategies.
An elimination initiative has been launched in South East Asia region showing
political commitment of Bangladesh, India and Nepal, with the aim to reduce VL
prevalence to less than 1 per 10 000 population by the year 2015.
Visceral leishmaniasis or kala‐azar is caused by the protozoan Leishmania donovani and
is a type of leishmaniasis that affects internal organ (other leishmaniasis infection
involve skin and mucous membrane). The transmission cycle can be zoonotic or
anthroponotic, although in this region, human is the only reservoir. VL affects poor
communities in remote, rural areas and clustered within households. VL is diverse and
complex, a typical example of neglected tropical disease, and known to prolong the
cycle of poverty as people lost productivity and can not afford treatment.
The death toll from the disease is estimated at around 50,000, which is surpassed only
by malaria among the parasitic diseases. VL almost completely disappeared from the
Indian subcontinent following the large scale anti malarial DDT spraying campaign in the
1950s. Unfortunately the disease quickly re‐emerged when these campaigns were
terminated and sandfly vector population increased again.
Regional burden of visceral leishmaniasis
VL can be found in more than 60 countries in the world, with a total of 200 million
people at risk. However, the majority (more than 90%) of VL cases occur in just six
countries: Bangladesh, India, Nepal, Sudan, Ethiopia and Brazil.
In SEA region, the three most affected countries are Bangladesh, India and Nepal,
spread over 109 districts. Bhutan has officially documented VL cases in 2007. India bears
the highest burden of VL cases, with Bihar state contributing 80‐90% of the reported
cases.
Characteristics and Transmission
Humans are infected via the bite of phlebotomine sandflies, which have the parasite
Leishmania inside them and inject them to humans. Only female flies can transmit the
disease. These flies normally breed in forest areas, caves, cracks in the mud walls, or the
burrows of small rodents. That is why in some villages, when houses are in close
proximity with cattle or cattlesheds, there are high probability of having sandflies
around. The period between sandfly bite until appearance of symptoms is between 2
and 6 months. This is quite a long period, and that is why VL is not easily diagnosed.
The people who get Vl suffer from fever, fatigue, weakness, loss of appetite, weight loss,
and enlarged lymph nodes/glands, liver and spleen. As the disease advances, the
splenomegaly can cause abdominal distension and pain. VL will eventually lead to death
unless treated. VL symptoms often persist for several weeks or months, and weaken the
immune system leading to pneumonia or other secondary infections. Patients can die
either due to these co‐infections, massive bleeding or severe anaemia.
After treatment, 5‐10% patients can also develop Post Kala‐azar Dermal Leishmaniasis
or PKDL, a skin lesion which usually appears between 1 to 3 years after cure.
Diagnosis and Treatment
The gold standard of VL is parasite detection through microscopic examination. The
procedures to get the samples from lymph node, bone marrow, or spleen aspirate
require considerable technical expertise and potentially dangerous, thus can not be
done everywhere.
The most commonly used now is tests that detect antibody, a marker that the body
produces after infected by VL. The most widely used are the direct agglutination test
(DAT) and immunochromatographic lateral flow method using rK39 antigen. The rK39
rapid test has many advantages as they are easy to perform, quick (results in 10‐20
minutes), and cheap (around US$ 1 per test). They are currently best diagnostic tool
available that can be used in remote places, albeit their performances vary. Fortunately,
for Indian kala‐azar, the sensitivity and specificity of these tests are satisfactory. There is
further research ongoing to improve current tools for diagnosing VL.
During the past decade, several breakthroughs in the treatment of VL has been made, as
the conventional treatment for VL is antimonial, a very old and toxic element. Today
there are more options such the first oral drug (Miltefosine) and others uch as
amphotericin B, liposomal amphotericin B, and paromomycin. Combination therapy has
also been explored as way to improve cost‐effectiveness and prevent drugs resistance.
Prevention and control
The current control strategies rely on reservoir and vector control and of course early
diagnosis and treatment of cases. When burden is high, active case findings can also be
carried out. Sandflies are susceptible to the same insecticides like malaria vector, and
residual insecticide spraying of houses and animal shelters was shown to be efficacious
in India. Another component is environmental control, such as plastering cracks in the
house wall and change the proximity with animal shelter.
The used of insecticide impregnated/treated bednets (ITNs) could also prevent VL and
other vector‐borne diseases such as malaria or Japanese encephalitis. However, there is
limited evidence that bednets provide protection against VL in paerticular, as
effectiveness of the bed nets depend on sleeping traditions of the population and the
biting habits of the local vectors.
Elimination initiative and challenges
Despite the difficulties to control VL in the world, there are several factors specific to
Indian subcontinent that makes elimination feasible. Biological factors include
anthroponotic cycle, with humans being the only reservoir and Phlebotomus argentipes
sandflies the only known vector. New and more effective diagnostic test (the rK39 ICTs)
and drugs (such as miltefosine) are available and can be used in the field. More
importantly, there is strong political commitment and inter‐country collaboration.
The VL elimination initiative was launched in 2005 by the signing of a Memorandum of
Understanding among India, Bangladesh and Nepal. The target is set for 2015., to
reduce annual incidence of kala azar to less than one per 10 000 population at district or
sub‐district level and to reduce case fatality rates.
The strategies for elimination are:
Early diagnosis and complete case management
Integrated vector management and vector surveillance
Effective disease surveillance through passive and active case detection
Social mobilization and building partnerships
Implementation and operational research
Capacity building
The challenges facing elimination of kala‐azar are abound:
The wide gap between the number of reported and estimated cases
Limited access to diagnosis and treatments, meaning patients still seek care from
private doctors or untrained people who provide expensive, incomplete or
inappropriate treatment.
Post kala azar dermal leishmaniasis (PKDL) patienst with only skin signs resulting
from delayed or incomplete treatment, are reservoirs of infection responsible for
continued transmission.
Rising co‐infection with HIV/AIDS
Visceral Leishmaniasis / Kala‐azar
Key facts
Visceral leishmaniasis, commonly known as kala‐azar, is a parasitic disease
caused by Leishmania protozoan and transmitted by sandflies.
It is one of neglected tropical diseases which can be fatal if not treated, with an
estimated 500,000 cases occur annually.
Symptoms include prolonged fever, weight loss, swelling of liver and spleen and
anaemia.
There are new tools available for diagnosis and treatment of VL, including rapid
tests and single dose treatment.
Vector control, surveillance and research are other component of control
strategies.
An elimination initiative has been launched in South East Asia region showing
political commitment of Bangladesh, India and Nepal, with the aim to reduce VL
prevalence to less than 1 per 10 000 population by the year 2015.
Visceral leishmaniasis or kala‐azar is caused by the protozoan Leishmania donovani and
is a type of leishmaniasis that affects internal organ (other leishmaniasis infection
involve skin and mucous membrane). The transmission cycle can be zoonotic or
anthroponotic, although in this region, human is the only reservoir. VL affects poor
communities in remote, rural areas and clustered within households. VL is diverse and
complex, a typical example of neglected tropical disease, and known to prolong the
cycle of poverty as people lost productivity and can not afford treatment.
The death toll from the disease is estimated at around 50,000, which is surpassed only
by malaria among the parasitic diseases. VL almost completely disappeared from the
Indian subcontinent following the large scale anti malarial DDT spraying campaign in the
1950s. Unfortunately the disease quickly re‐emerged when these campaigns were
terminated and sandfly vector population increased again.
Regional burden of visceral leishmaniasis
VL can be found in more than 60 countries in the world, with a total of 200 million
people at risk. However, the majority (more than 90%) of VL cases occur in just six
countries: Bangladesh, India, Nepal, Sudan, Ethiopia and Brazil.
In SEA region, the three most affected countries are Bangladesh, India and Nepal,
spread over 109 districts. Bhutan has officially documented VL cases in 2007. India bears
the highest burden of VL cases, with Bihar state contributing 80‐90% of the reported
cases.
Characteristics and Transmission
Humans are infected via the bite of phlebotomine sandflies, which have the parasite
Leishmania inside them and inject them to humans. Only female flies can transmit the
disease. These flies normally breed in forest areas, caves, cracks in the mud walls, or the
burrows of small rodents. That is why in some villages, when houses are in close
proximity with cattle or cattlesheds, there are high probability of having sandflies
around. The period between sandfly bite until appearance of symptoms is between 2
and 6 months. This is quite a long period, and that is why VL is not easily diagnosed.
The people who get Vl suffer from fever, fatigue, weakness, loss of appetite, weight loss,
and enlarged lymph nodes/glands, liver and spleen. As the disease advances, the
splenomegaly can cause abdominal distension and pain. VL will eventually lead to death
unless treated. VL symptoms often persist for several weeks or months, and weaken the
immune system leading to pneumonia or other secondary infections. Patients can die
either due to these co‐infections, massive bleeding or severe anaemia.
After treatment, 5‐10% patients can also develop Post Kala‐azar Dermal Leishmaniasis
or PKDL, a skin lesion which usually appears between 1 to 3 years after cure.
Diagnosis and Treatment
The gold standard of VL is parasite detection through microscopic examination. The
procedures to get the samples from lymph node, bone marrow, or spleen aspirate
require considerable technical expertise and potentially dangerous, thus can not be
done everywhere.
The most commonly used now is tests that detect antibody, a marker that the body
produces after infected by VL. The most widely used are the direct agglutination test
(DAT) and immunochromatographic lateral flow method using rK39 antigen. The rK39
rapid test has many advantages as they are easy to perform, quick (results in 10‐20
minutes), and cheap (around US$ 1 per test). They are currently best diagnostic tool
available that can be used in remote places, albeit their performances vary. Fortunately,
for Indian kala‐azar, the sensitivity and specificity of these tests are satisfactory. There is
further research ongoing to improve current tools for diagnosing VL.
During the past decade, several breakthroughs in the treatment of VL has been made, as
the conventional treatment for VL is antimonial, a very old and toxic element. Today
there are more options such the first oral drug (Miltefosine) and others uch as
amphotericin B, liposomal amphotericin B, and paromomycin. Combination therapy has
also been explored as way to improve cost‐effectiveness and prevent drugs resistance.
Prevention and control
The current control strategies rely on reservoir and vector control and of course early
diagnosis and treatment of cases. When burden is high, active case findings can also be
carried out. Sandflies are susceptible to the same insecticides like malaria vector, and
residual insecticide spraying of houses and animal shelters was shown to be efficacious
in India. Another component is environmental control, such as plastering cracks in the
house wall and change the proximity with animal shelter.
The used of insecticide impregnated/treated bednets (ITNs) could also prevent VL and
other vector‐borne diseases such as malaria or Japanese encephalitis. However, there is
limited evidence that bednets provide protection against VL in paerticular, as
effectiveness of the bed nets depend on sleeping traditions of the population and the
biting habits of the local vectors.
Elimination initiative and challenges
Despite the difficulties to control VL in the world, there are several factors specific to
Indian subcontinent that makes elimination feasible. Biological factors include
anthroponotic cycle, with humans being the only reservoir and Phlebotomus argentipes
sandflies the only known vector. New and more effective diagnostic test (the rK39 ICTs)
and drugs (such as miltefosine) are available and can be used in the field. More
importantly, there is strong political commitment and inter‐country collaboration.
The VL elimination initiative was launched in 2005 by the signing of a Memorandum of
Understanding among India, Bangladesh and Nepal. The target is set for 2015., to
reduce annual incidence of kala azar to less than one per 10 000 population at district or
sub‐district level and to reduce case fatality rates.
The strategies for elimination are:
Early diagnosis and complete case management
Integrated vector management and vector surveillance
Effective disease surveillance through passive and active case detection
Social mobilization and building partnerships
Implementation and operational research
Capacity building
The challenges facing elimination of kala‐azar are abound:
The wide gap between the number of reported and estimated cases
Limited access to diagnosis and treatments, meaning patients still seek care from
private doctors or untrained people who provide expensive, incomplete or
inappropriate treatment.
Post kala azar dermal leishmaniasis (PKDL) patienst with only skin signs resulting
from delayed or incomplete treatment, are reservoirs of infection responsible for
continued transmission.
Rising co‐infection with HIV/AIDS