Visceral leishmaniasis

About: Visceral leishmaniasis is a research topic. Over the lifetime, 7486 publications have been published within this topic receiving 184865 citations. The topic is also known as: Kala-Azar & viscus leishmaniasis.

Recent developments in drug discovery for leishmaniasis and human African trypanosomiasis.

Abstract: Leishmaniasis is a parasitic disease that presents four main clinical syndromes: cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), visceral leishmaniasis/kala azar (VL), and post kala azar dermal leishmaniasis (PKDL). Causative Leishmania are protozoan parasites that are transmitted among mammalian hosts by phlebotomine sandflies. In mammalian hosts, parasite cells proliferate inside the host phagocytic cells as round amastigotes. Infection of sandflies with Leishmania occurs during insect feeding on infected mammalian hosts. After introduction into the insect gut together with the blood meal, Leishmania amastigotes transform into elongated flagellated promastigotes that propagate in the insect gut. A new round of infection is initiated after the infected sandfly takes a blood meal from a naive mammalian host and introduces Leishmania parasites into the bite wound in the host dermis (Scheme 1). More than 20 different Leishmania species have been found to cause human leishmaniasis (Table 1). Leishmaniasis is endemic in 98 countries and is closely associated with poverty. More than a million new cases are reported per year and 350 million people are at risk of contracting the infection. For the most severe form of leishmaniasis, VL, ∼300 000 new cases are estimated to occur annually resulting in ∼40 000 deaths. Approximately 90% of all VL cases occur in 3 endemic foci: 1. India, Bangladesh, and Nepal; 2. East Africa; and 3. Brazil. In spite of the high prevalence, currently available treatments for leishmaniasis are inadequate. Pentavalent antimonials, the standard treatment for leishmaniasis for many decades, are not efficacious in Bihar (∼60% of VL cases worldwide) any longer due to widespread resistance to the drug in this region. Several new VL treatments have emerged during the past 10–15 years, but each has serious shortcomings (summarized in Table 2). These include paromomycin (injectable, long treatment, region-dependent efficacy), miltefosine (cost, teratogenicity, long treatment), and liposomal amphotericin B (cost, hospitalization, region-dependent efficacy). An additional challenge is represented by patients with HIV/VL coinfections who are more difficult to cure (lower initial and final cure rates), have greater susceptibility to drug toxicity, and have higher rates of death and relapse. Due to the limitations of the existing treatments, better drugs are urgently needed. Ideally, new VL drugs would be efficacious across all endemic regions, would affect cure in ≤10 days, and would cost <$10 per course (for a complete target product profile for new VL drugs, which was formulated by DNDi, see Table 4).1 Here we describe the disease history and parasite biology followed by a summary of the currently available treatments and, finally, review reports of novel small molecules with antileishmanial activity.

Chemotherapy of leishmaniasis: past, present and future.

Abstract: Leishmaniasis is a parasitic disease caused by hemoflagellate, Leishmania spp. The parasite is transmitted by the bite of an infected female phlebotomine sandfly. The disease is prevalent throughout the world and in at least 88 countries. Nearly 25 compounds are reported to have anti-leishmanial effects but not all are in use. The pentavalent antimony compounds have remained mainstay for nearly 75 years. Pentavalent antimony is a prodrug that is reduced by glutathione to active trivalent species catalyzed by thiol-dependent-reductase. However, emergence of resistance led to the use of other compounds -amphotericin B, pentamidine, paromomycin, allopurinol etc. Amphotericin B, an antifungal macrolide polyene is characterized by the hydrophilic polyhydroxyl and hydrophobic polyene faces on it long axis. Presently, it is the only drug with highest cure rate. It acts on membrane sterols resulting in parasite cell lysis. Its lipid formulations have been developed to minimize side effects. Other anti-fungals like ketoconazole, fluconazole and terbinafine are found less effective. Recently, anticancer alkylphosphocholines have been found most effective oral compounds. These act as membrane synthetic ether-lipid analogues, and consist of alkyl chains in the lipid portions. Most promising of these are miltefosine (hexadecylphosphocholine), edelfosine (ET-18-OCH3) and ilmofosine (BM 41.440). However, the recent focus has been on identifying newer therapeutic targets in the parasite such as DNA topoisomerases. The present review describes the current understanding of different drugs against leishmaniasis, their chemistry, mode of action and the mechanism of resistance in the parasite. Future perspectives in the area of new anti-leishmanial drug targets are also enumerated. However, due to the vastness of the topic main emphasis is given on visceral leishmaniasis.

Control of zoonotic visceral leishmaniasis: Is it time to change strategies?

Abstract: Zoonotic visceral leishmaniasis (ZVL) is an important emerging parasitic disease. This article reviews the recommended control methods for the disease and concludes that they have only been partially effective. The continued endemicity of ZVL, its recent appearance in urban areas of Latin America, and its increasing importance as an opportunistic infection among persons infected with human immunodeficiency virus indicate that present control methods for the disease are ineffective and that new control strategies are needed. Prevention of the disease in dogs appears to be the best approach for interrupting the domestic cycle of ZVL. The most feasible approach would seem to be a canine vaccine that protects dogs from developing parasitemia and from becoming peridomestic reservoirs of the parasite.