Two species of Leishmania are known to give rise to the<unk>  form of the disease. The species commonly found in East Africa and the Indian subcontinent is L. donovani and the species found in Europe, North Africa, and Latin America is L. infantum, also known as L. chagasi. The insect vectors are species of sandfly of the genus Phlebotomus in the Old World, and of Lutzomyia in the New World. Sandflies are tiny flies, measuring 3–6 mm long by 1.5–3 mm in diameter, and are found in tropical or temperate regions throughout the world. The sandfly species Lutzomyia longipalpis is the primary vector of this disease. The larvae grow in warm, moist organic matter (such as old trees, house walls, or waste) making them hard to eradicate.<unk> /kala-azar samples from India revealed the presence of not only the primary causative protozoan parasite, i.e. Leishmania donovani (LD) but also co-infection with another protozoan member called Leptomonas seymouri (LS). The latter parasite (LS) further contained a RNA virus known as Leptomonas seymouri narna-like virus 1 (Lepsey NLV1). So, it appears that a great majority of<unk>  victims in the Indian subcontinent are exposed to a RNA virus in LS, the co-infecting parasite with LD i.e. the "LD-LS-Lepsey NLV1 triple pathogen" phenomenon. Life cycle The life cycle of Leishmania is completed in two hosts, humans and sandflies. The adult female sandfly is a bloodsucker, usually feeding at night on sleeping prey. When the fly bites an individual infected with Leishmania, the pathogen is ingested along with the prey's blood. The protozoan is in the smaller of its two forms, called an amastigote, which is round, non-motile, and only 3–7 micrometers in diameter. Inside the stomach of the sandfly, the amastigotes quickly transform into elongated and motile forms called the promastigotes. Promastigote is spindle-shaped, triple the size of the amastigote, and has a single flagellum that allows mobility. The promastigotes live extracellularly in the alimentary canal, reproducing asexually, then migrate to the proximal end of the gut where they become poised for a regurgitational transmission. As the fly bites, the promastigotes are released from the proboscis and introduced locally at the bite site. Once inside the human host, promastigotes invade macrophages. Inside the cells they transform back into the smaller amastigote form. The amastigotes replicate in the most hostile part of the macrophage cell, inside the phagolysosome, whose normal defensive response they are able to prevent. After repeated multiplication, they break down their host cell by sheer pressure of mass, but there is some recent speculation that they are able to leave the cell by triggering the exocytosis response of the macrophage. The daughter cells protozoans then migrate to fresh cells or through the bloodstream to find new hosts. In this way the infection is progressive, spreading to the host's mononuclear phagocyte system, particularly the spleen and liver. The free amastigotes in peripheral tissues are then ingested by sandfly to enter another cycle.
Visceral leishmaniasis
Psittacosis
Leishmaniasis
African trypanosomiasis
Babesiosis
Human trypanosomiasis
Trypanosomiasis
Cutaneous leishmaniasis