Visceral leishmaniasis

Visceral leishmaniasis
Amastigotes of Leishmania in a chorionic villus
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Visceral leishmaniasis, also known as kala-azar, is a severe form of leishmaniasis caused by protozoan parasites of the Leishmania genus. It is transmitted by the bite of infected sandflies. The disease is characterized by irregular bouts of fever, substantial weight loss, swelling of the spleen and liver, and anemia.

Epidemiology

Visceral leishmaniasis is endemic in parts of the Indian subcontinent, East Africa, and Brazil. It is estimated that 50,000 to 90,000 new cases occur annually, with a significant number of deaths if untreated. The disease is closely associated with poverty, malnutrition, and environmental changes that increase exposure to sandflies.

Pathophysiology

The Leishmania parasites invade the host's reticuloendothelial system, primarily affecting the spleen, liver, and bone marrow. The parasites multiply within macrophages, leading to the characteristic symptoms of the disease. The immune response to the infection can cause further damage to the host tissues.

Clinical Presentation

Patients with visceral leishmaniasis typically present with prolonged fever, weight loss, and splenomegaly. Hepatomegaly and lymphadenopathy may also be observed. Anemia and leukopenia are common laboratory findings. If left untreated, the disease can be fatal due to complications such as secondary infections and severe anemia.

Diagnosis

Diagnosis of visceral leishmaniasis is confirmed by identifying the parasites in tissue samples, such as bone marrow or spleen aspirates, using microscopy. Serological tests and polymerase chain reaction (PCR) are also used to detect Leishmania DNA or antibodies.

Treatment

The treatment of visceral leishmaniasis involves the use of antileishmanial drugs. Pentavalent antimonials, such as sodium stibogluconate, have been the mainstay of treatment. Liposomal amphotericin B is also effective and is often used in cases of drug resistance or intolerance. Miltefosine, an oral drug, is another option for treatment.

Prevention

Preventive measures focus on reducing exposure to sandflies. This includes the use of insecticide-treated bed nets, indoor residual spraying, and environmental management to reduce sandfly breeding sites. Public health education and improving socio-economic conditions are also crucial in controlling the spread of the disease.

History

The disease was first described in the 19th century, and significant contributions to its understanding were made by scientists such as Sir Upendra Nath Brahmachari, who developed a treatment for kala-azar.

Sir Upendra Nath Brahmachari, who developed a treatment for kala-azar

Also see

• Leishmaniasis
• Cutaneous leishmaniasis
• Mucocutaneous leishmaniasis
• Sandfly

References

• World Health Organization. "Leishmaniasis." WHO, 2023.
• Centers for Disease Control and Prevention. "Parasites - Leishmaniasis." CDC, 2023.