Visceral leishmaniasis
Symptoms, transmission, and current treatments for visceral leishmaniasis
Visceral leishmaniasis
Symptoms, transmission, and current treatments for visceral leishmaniasis
What is visceral leishmaniasis?
Also known as kala-azar, visceral leishmaniasis is a life-threatening disease caused by Leishmania parasites which are transmitted by female sandflies. Visceral leishmaniasis causes fever, weight loss, spleen and liver enlargement, and, if not treated, death.
Visceral leishmaniasis has strong links to poverty, taking its heaviest toll on people affected by malnutrition, poor housing, and displacement. People living with HIV who develop visceral leishmaniasis are at a particularly high risk of severe disease, treatment failure, and death. Around half of all people diagnosed with leishmaniasis are children.
A skin condition known as post-kala-azar dermal leishmaniasis (PKDL) may develop months or years after successful treatment for visceral leishmaniasis. While it is not life-threatening, PKDL can be disfiguring and stigmatizing – and PKDL lesions can act as a reservoir for Leishmania parasites, allowing onward transmission of visceral leishmaniasis that can complicate efforts to eliminate the disease.
What is the impact of visceral leishmaniasis?
- 95% fatal if left untreated
- 50,000-90,000 new cases per year, with only 25-45% cases reported
- 5,710 deaths in 2019
- More than 100x higher risk of developing active visceral leishmaniasis in people living with HIV
- 5-10% of people treated for visceral leishmaniasis develop PKDL
- In 2023, about 83% of cases were reported from 7 countries: Brazil, Ethiopia, India, Kenya, Somalia, South Sudan, and Sudan.
- About 50% of people infected with visceral leishmaniasis are children
What are the current drugs for visceral leishmaniasis?
Leishmaniasis treatment depends on several factors, including the form of the disease, parasite species, and geographic location. Existing drugs have serious drawbacks in terms of safety, resistance, stability, and cost. They have low tolerability, a long treatment duration when used individually, and are difficult to administer.
Pentavalent antimonials (sodium stibogluconate and meglumine antimoniate)
- 30-day treatment by infusion, if given on its own
- Resistance has been seen in areas where the disease is very common
- Toxic, with risk of serious cardiotoxicity leading to death
Liposomal amphotericin B
- Much safer and highly effective in some regions: a single 10mg/kg infusion has a cure rate of greater than 90% in Asia
- Expensive and needs to be stored in a fridge
Miltefosine
- 28-day, twice-a-day oral drug
- Nausea and vomiting are common side effects that may affect adherence to the four-week treatment
- Cannot be used during pregnancy
- Not available in many countries
Paromomycin
- Three weeks of painful intramuscular injections
- Low-cost formulation
- Associated with toxic effects on the kidneys and ears
- Limited efficacy when used on its own in Eastern Africa
What new treatments for visceral leishmaniasis are needed?
The World Health Organization (WHO) has set a target to eliminate visceral leishmaniasis as a public health problem by 2030, with specific targets for different regions. To reach these targets – and sustain them – new treatments that are safe, effective, affordable, and adapted to local conditions are urgently needed.
In South-East Asia, the elimination goal is an incidence of less than one case per 10,000 population at the sub-district level – achieved by Bangladesh in 2023. In Eastern Africa, the elimination target is defined as < 1% case-fatality rate due to primary VL, with a 90% reduction in visceral leishmaniasis cases by 2030. This target was agreed by several Eastern African nations and formalized through the 2024 Nairobi Declaration and a subsequent historic regional strategic framework for the elimination of visceral leishmaniasis as a public health problem.
What visceral leishmaniasis treatments are we working on?
We aim to make treatments safer, shorter, more affordable, and more effective. In the short term, we are developing better treatment regimens using existing drugs. In the longer term, our goal is to develop entirely new all-oral drugs that are safe, effective, affordable, and accessible to the people who need them most.
Find out about our work developing treatments for visceral leishmaniasis
How do you get visceral leishmaniasis?
- Visceral leishmaniasis is caused by Leishmania parasites that are transmitted through the bites of infected female phlebotomine sandflies.
- Sandfly breeding and biting rates are affected by climatic and environmental factors.
- Poor housing, displacement, and lack of adequate access to sanitation can increase the risk of infection.
- People affected by malnutrition or other conditions that compromise the immune system, such as HIV, are more likely to develop severe disease.
What are the symptoms of visceral leishmaniasis?
Visceral leishmaniasis has symptoms that occur progressively over a period of weeks or even months:
- prolonged fever
- enlarged spleen and liver
- substantial weight loss
- progressive anaemia
Visceral leishmaniasis is usually fatal if left untreated.
How is visceral leishmaniasis diagnosed?
Visceral leishmaniasis is diagnosed by combining observations from a physical exam by a health worker with parasitological or antibody-based diagnostics. The main signs are prolonged fever, weight loss, enlargement of the spleen, and anaemia. Several rapid diagnostic tests are available for use in field conditions.
People with visceral leishmaniasis symptoms but negative diagnostic results are referred to hospitals or clinics where microscopic examination of tissue aspirate (spleen, bone marrow, or lymph node) is available. If performed incorrectly, spleen aspiration can cause fatal bleeding.
Easy-to-use, non-invasive diagnostics that can be used in remote settings by health workers with limited training are critical to improving patient care and visceral leishmaniasis control.
More information
Last updated: September 2025
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