Visceral leishmaniasis

Visceral Leishmaniasis

Visceral leishmaniasis (VL), also known as kala-azar, is the most severe form of leishmaniasis, a disease caused by protozoan parasites of the genus Leishmania. Visceral leishmaniasis affects the body's internal organs, such as the spleen, liver, and bone marrow, and is fatal if left untreated.

Overview

Visceral leishmaniasis is characterized by fever, weight loss, splenomegaly (enlargement of the spleen), hepatomegaly (enlargement of the liver), and anemia. The disease is transmitted through the bites of infected female phlebotomine sandflies.

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A phlebotomine sandfly, the vector of Leishmania parasites.

Causative Agent

The disease is caused by several species of the Leishmania genus, primarily Leishmania donovani and Leishmania infantum (also known as Leishmania chagasi in Latin America).

Transmission

VL is transmitted to humans through the bite of infected female phlebotomine sandflies, which acquire the parasite by feeding on infected animals or humans.

Epidemiology

Visceral leishmaniasis is endemic in parts of Asia, Africa, South America, and the Mediterranean region. It is estimated that there are 50,000 to 90,000 new cases of VL worldwide each year.

Clinical Manifestations

After an incubation period that can range from weeks to months, individuals infected with VL may develop:

• Persistent fever
• Weight loss
• Fatigue
• Enlargement of the spleen and liver
• Anemia and leukopenia

Diagnosis

Diagnosis of VL is based on clinical signs and confirmed through laboratory tests, including:

• Serological tests to detect antibodies against Leishmania parasites
• Parasitological examination of bone marrow, spleen, or lymph node aspirates
• Molecular tests, such as PCR, to identify Leishmania DNA

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Microscopic view of Leishmania parasites in a spleen aspirate.

Treatment

Treatment for VL typically involves the administration of antileishmanial drugs, such as:

• Amphotericin B
• Miltefosine
• Pentavalent antimonials

Early diagnosis and treatment are crucial to prevent fatal outcomes and reduce the risk of developing post-kala-azar dermal leishmaniasis (PKDL), a complication that can occur after treatment.

Prevention and Control

Prevention of VL focuses on reducing contact with sandflies and controlling the sandfly population. Strategies include:

• Use of insecticide-treated bed nets
• Indoor residual spraying with insecticides
• Personal protective measures, such as wearing long-sleeved clothing and applying insect repellent

External Links

• World Health Organization - Leishmaniasis
• CDC - Parasites - Leishmaniasis

References

• Control of the Leishmaniases by the World Health Organization
• Leishmaniasis: Epidemiology, Control and Prevention edited by David Claborn

Visceral leishmaniasis Resources
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