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Leishmaniasis

Leishmaniasis is a disease caused by parasites that belong to the genus Leishmania and is transmitted by the bite of certain species of sandfly, including flies in the genus Lutzomyia in the new world and Phlebotomus in the old world.

Synonyms for leishmaniasis include kala azar, black fever, sandfly disease, Dum-Dum fever and espundia. The disease is named for William Boog Leishman.

Most forms of the disease are transmittable only from animals (zoonosis), but some can be spread between people. Human infection is caused by about 21 of 30 species that infect mammals. These include the L. donovani complex with 3 species (L. donovani, L. infantum, and L. chagasi); the L. mexicana complex with 3 main species (L. mexicana, L. amazonensis, and L. venezuelensis); L. tropica; L. major; L. aethiopica; and the subgenus Viannia with 4 main species (L. (V.) braziliensis, L. (V.) guyanensis, L. (V.) panamensis, and L. (V.) peruviana). The different species are morphologically indistinguishable, but they can be differentiated by isoenzyme analysis, molecular methods, or monoclonal antibodies.

Signs and symptoms

The symptoms of leishmaniasis are skin sores which erupt weeks to months after the person affected is bitten by sand flies. Other consequences, which can become manifest anywhere from a few months to years after infection, include fever, damage to the spleen and liver, and anaemia.

In the medical field, leishmaniasis is one of the famous causes of a markedly enlarged spleen (larger even than the liver). There are four main forms of leishmaniasis:

Visceral leishmaniasis - the most serious form and potentially fatal if untreated.

Cutaneous leishmaniasis - the most common form which causes numerous sores on the body, which heal within a few months leaving unpleasant looking scars.

Diffuse cutaneous leishmaniasis - this form produces widespread skin lesions which resemble leprosy and is particularly difficult to treat.

Mucocutaneous leishmaniasis - commences with skin ulcers which spread causing tissue damage to (particularly) nose and mouth

There are two common therapies containing antimony, antimoniate de méglumine (Glucantime) and sodium stibogluconate (Pentostam). It is not completely understood how these drugs act against the parasite, possibly by disrupting its energy production or trypanothione metabolism.

Treatment

There are no vaccines available for this disease. The genome of the parasite has been allowing for identification of proteins that are made by the disease but not by humans. These proteins are potential targets for drug treatments. (Ivens, et al., 2005)

Miltefosine (Impavido ®), is a new drug for visceral (and probably also cutaneous) leishmaniasis. The cure rate of miltefosine in phase III clinical trials is 95%. Miltefosine had already received approval by the Indian and German Regulatory Authorities (2003) and is the first orally administered breakthrough therapy for visceral leismaniasis, which leads to death if left untreated for 0.5-2 years. (More, et al, 2003)

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