Revised May 2000

Transmitted by the bite of the infected female phlebotomine sandfly, the leishmaniases are a globally widespread group of parasitic diseases. The sandfly vector is usually infected with one species of flagellate protozoa belonging to the genus Leishmania.

About 30 species of sandflies can become infected when taking a blood meal from a reservoir host. Hosts are infected humans, wild animals, such as rodents, and domestic animals, such as dogs. Most leishmaniases are zoonotic (transmitted to humans from animals), and humans become infected only when accidentally exposed to the natural transmission cycle. However, in the anthroponotic forms (those transmitted from human to human through the sandfly vector), humans are the sole reservoir host.

Leishmaniasis presents itself in humans in four different forms with a broad range of clinical manifestations. All forms can have devastating consequences.

Visceral leishmaniasis (VL), also known as kala azar, is the most severe form of the disease, which, if untreated, has a mortality rate of almost 100%. It is characterized by irregular bouts of fever, substantial weight loss, swelling of the spleen and liver, and anaemia.

Mucocutaneous leishmaniasis (MCL), or espundia, produces lesions which can lead to extensive and disfiguring destruction of mucous membranes of the nose, mouth and throat cavities.

Cutaneous leishmaniasis (CL) can produce large numbers of skin ulcers - as many as 200 in some cases - on the exposed parts of the body, such as the face, arms and legs, causing serious disability and leaving the patient permanently scarred. Diffuse cutaneous leishmaniasis (DCL) never heals spontaneously and tends to relapse after treatment. The cutaneous forms of leishmaniasis are the most common and represent 50-75% of all new cases.