Key facts

• Leishmaniasis is a parasitic disease transmitted by sandflies
• The disease occurs in several forms: cutaneous, mucocutaneous, and visceral (also known as kala-azar).
• It is endemic in parts of Asia, Africa, the Americas, and the Mediterranean region.
• Without prompt treatment, visceral leishmaniasis can be fatal.
• There are an estimated 700,000 to 1 million cases every year, with 30,000 of the most severe form

Overview

Leishmaniasis is a neglected tropical disease that affects millions of people worldwide. The disease is caused by infection with Leishmania parasites, which are carried by sandflies.

There are three main forms of the disease: cutaneous leishmaniasis, the most common form; mucocutaneous; and visceral leishmaniasis, the most severe form.

It is a disease of poverty and affects people living in crowded areas where there is poor sanitation, providing breeding grounds for sandflies.

Signs and symptoms

The signs and symptoms vary depending on the type of leishmaniasis. Typical symptoms include:

• Skin sores or ulcers at the site of a sandfly bite (cutaneous)
• Sores in the nose, mouth, or throat (mucocutaneous)
• Fever (visceral)
• Weight loss (visceral)
• Enlargement of the spleen and liver (visceral)
• Anaemia and fatigue (visceral)

Dangers and complications

Cutaneous leishmaniasis, while rarely fatal, can lead to disfiguring scars. Mucocutaneous leishmaniasis causes severe facial disfigurement that may lead to difficulties in eating, speaking and breathing.

If visceral leishmaniasis is untreated, it almost always results in death due to progressive organ failure, malnutrition, or secondary infections. Relapses are also possible even after treatment, especially in individuals with weakened immune systems. People living with HIV who are infected with leishmaniasis are more likely to develop the most severe form of the disease as both suppress the immune system.

Transmission

Leishmaniasis is transmitted through the bite of infected female phlebotomine sandflies. These insects become infected after feeding on animals or humans carrying the parasite. It does not spread directly from human to human.

Treatment

Leishmaniasis is a treatable and curable disease but early treatment is crucial, particularly for visceral leishmaniasis. Treatment depends on the form of the disease, the species of parasite, and the patient’s health status.

Prevention

Prevention mainly focuses on avoiding sandfly bites by using insecticide-treated bed nets, repellents, and protective clothing. Sandflies are much smaller than mosquitoes so mesh covers on windows and bed nets must have small holes. There is no vaccination against the disease.

History

Leishmaniasis is an ancient disease but it was only first clinically described in the 18th and 19th centuries. William Leishman, a Scottish army doctor, was the first to identify the parasite which he found in the spleen of an English private who had died of Dumdum fever in Dum-Dum, near Kolkata, India. Today, it is considered a neglected tropical disease. Numbers of visceral leishmaniasis have fallen from around 65,000 cases in 2011 to 11,000 in 2023. However, cases of the cutaneous form increased over the same period from 213,000 to 271,000 – although this may be due to better reporting. In 2023 90 per cent of new cases occurred in just 11 countries: Afghanistan, Pakistan, Syria, Brazil, Algeria, Peru, Colombia, Iran, Iraq, Yemen and Sri Lanka.

Useful links

unitingtocombatntds.org/disease-directory/Leishmaniasis-cutaneous-and-visceral/

cdc.gov/leishmaniasis/prevention

who.int/fact-sheets/leishmaniasis

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