Impact

Leishmaniasis is a parasitic disease transmitted by the bite of a sandfly that is infected with Leishmania parasites. Currently, 350 million people in 88 countries around the world are threatened, and 12 million people are affected by leishmaniasis. Of the 1.5 – 2 million new cases of leishmaniasis estimated to occur annually, most occur in the tropics and subtropics, including the Middle East. But the disease is now being seen in the U.S. as American soldiers stationed in the Middle East are returning infected with the disease, and travelers to endemic areas are also at risk. Leishmaniasis is considered a threat in southwestern Europe, such as Spain, Italy, France and Portugal. The geographic spread is due to factors related to development, including massive rural-urban migration and agro-industrial projects that bring non-immune urban dwellers into endemic rural areas. Manmade projects with environmental impact, like wells, irrigation systems and dams, as well as deforestation, also contribute to the spread of leishmaniasis.

Symptoms

With the bite of an infected sandfly, Leishmania parasites are passed from one infected animal or human to others. Leishmaniasis is a spectrum of diseases, each distinctly manifested and all with potentially devastating consequences — disfigurement, damage to internal organs, death. Depending on the species of the infecting parasite, the spleen, liver, bone marrow, mucous membranes and/or skin may be attacked. Leishmania donovani, the most dangerous of these, causes Kala azar, or visceral leishmaniasis, characterized by fever, severe weight loss and anemia. If left untreated, visceral leishmaniasis can lead to death.

Seattle BioMed's Role

In collaboration with researchers around the world, Seattle BioMed has made progress in unraveling the mysteries of this and other diseases caused by parasites of the Trypanosomatidae family to which Leishmania belongs. The draft sequencing of the genome of the Leishmania major Friedlin parasite is now complete, opening the doorway for new drugs and therapeutics to follow. Research at Seattle BioMed has led to identification of an unusual arrangement of genes in these complex organisms. After a three-year effort, our scientists developed a way to turn genes on and off, allowing the study of these essential roles specific Leishmania genes play in causing disease. These and other discoveries are providing important clues to how gene structure and function are linked to critical cellular functions.