Alkylphospholipids and Leishmaniasis

Leishmaniasias is a complex of diseases caused by intracellular protozoan parasites that belong to the genus Leishmania (class: Kinetoplastida; order: Trypanosomatidae), for which there are more than 20 different species, and is transmitted by the bite of female phlebotomine sand flies (order: Diptera; family: Psychodidae; subfamily: Phlebotominae). Various species of phlebot‐ omine sand flies of the genus Phlebotomus are responsible for transmission of leishmaniasis in the Old World, and of the genus Lutzomyia in the New World [1]. Leishmania parasite has a digenetic life-cycle alternating between a mammalian host and insect vectors, phlebotomine sand flies, which are small (1.5-2 mm body length) insects mainly found in tropical and subtropical regions. Leishmania lives extracellularly as flagellated promastigotes in the gut and salivary glands of the sand fly vector, and intracellularly as amastigotes in the vertebrate host macrophages. Leishmania promastigotes, transmitted to mammalian skin by the bite of a female phlebotomine sand fly, invade human macrophages as the main host for the parasites, where Leishmania transforms into amastigotes and replicate intracellularly. Leishmaniasis represents a major international health problem, has a high morbidity and mortality rate, and is classified as an emerging and uncontrolled disease by the World Health Organization (WHO). The disease burden of leishmaniasis is high, with about 350 million people in 98 countries consid‐ ered at risk. Among parasitic diseases, leishmaniasis accounts for the second highest burden of disease after malaria, with a loss of about 2.4 million disability-adjusted life years (DALYs) [2, 3]. There are an estimated 1.5-2 million new cases per year, with 1.5 million cases of selfhealing, but disfiguring, (muco-)cutaneous leishmaniasis, and 500,000 cases of life-threatening visceral leishmaniasis [2, 3]. However, more than 90% of the world’s cases of visceral leish‐ maniasis are in India, Bangladesh, Nepal, Sudan, and Brazil. Some species tend to cause cutaneous leishmaniasis (e.g., L. major and L.tropica), whereas others lead to cause visceral leishmaniasis (e.g., L. infantum and L. donovani). Leishmaniases are usually classified based on the clinical manifestations, leading to three major clinical forms, namely: