Leishmania is a parasitic protozoan, a single-celled organism of the genus Leishmania that is responsible for the disease leishmaniasis. They are spread by sandflies of the genus Phlebotomus in the Old World, and of the genus Lutzomyia in the New World. At least 93 sandfly species are proven or probable vectors worldwide. Their primary hosts are vertebrates; Leishmania commonly infects hyraxes, canids, rodents, and humans.
Trypanosomatida is a group of kinetoplastid unicellular organisms distinguished by having only a single flagellum. The name is derived from the Greek trypano (borer) and soma (body) because of the corkscrew-like motion of some trypanosomatid species. All members are exclusively parasitic, found primarily in insects. A few genera have life-cycles involving a secondary host, which may be a vertebrate, invertebrate or plant. These include several species that cause major diseases in humans. Some trypanosomatida are intracellular parasites, with the important exception of Trypanosoma brucei.
Kinetoplastida is a group of flagellated protists belonging to the phylum Euglenozoa, and characterised by the presence of a distinctive organelle called the kinetoplast, a granule containing a large mass of DNA. The group includes a number of parasites responsible for serious diseases in humans and other animals, as well as various forms found in soil and aquatic environments. The organisms are commonly referred to as "kinetoplastids" or "kinetoplasts".
Leishmaniasis is a wide array of clinical manifestations caused by protozoal parasites of the Trypanosomatida genus Leishmania. It is generally spread through the bite of phlebotomine sandflies, Phlebotomus and Lutzomyia, and occurs most frequently in the tropics and sub-tropics of Africa, Asia, the Americas, and southern Europe. The disease can present in three main ways: cutaneous, mucocutaneous, or visceral. The cutaneous form presents with skin ulcers, while the mucocutaneous form presents with ulcers of the skin, mouth, and nose. The visceral form starts with skin ulcers and later presents with fever, low red blood cell count, and enlarged spleen and liver.
In biology, a biological life cycle is a series of stages of the life of an organism, that begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote which then itself goes through the same series of stages, the process repeating in a cyclic fashion.
Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question but by their way of life. This means it forms a synthesis of other disciplines, and draws on techniques from fields such as cell biology, bioinformatics, biochemistry, molecular biology, immunology, genetics, evolution and ecology.
Trypanosoma is a genus of kinetoplastids, a monophyletic group of unicellular parasitic flagellate protozoa. Trypanosoma is part of the phylum Euglenozoa. The name is derived from the Greek trypano- (borer) and soma (body) because of their corkscrew-like motion. Most trypanosomes are heteroxenous and most are transmitted via a vector. The majority of species are transmitted by blood-feeding invertebrates, but there are different mechanisms among the varying species. Trypanosoma equiperdum is spread between horses and other equine species by sexual contact. They are generally found in the intestine of their invertebrate host, but normally occupy the bloodstream or an intracellular environment in the vertebrate host.
Microsporidia are a group of spore-forming unicellular parasites. These spores contain an extrusion apparatus that has a coiled polar tube ending in an anchoring disc at the apical part of the spore. They were once considered protozoans or protists, but are now known to be fungi, or a sister group to fungi. These fungal microbes are obligate eukaryotic parasites that use a unique mechanism to infect host cells. They have recently been discovered in a 2017 Cornell study to infect Coleoptera on a large scale. So far, about 1500 of the probably more than one million species are named. Microsporidia are restricted to animal hosts, and all major groups of animals host microsporidia. Most infect insects, but they are also responsible for common diseases of crustaceans and fish. The named species of microsporidia usually infect one host species or a group of closely related taxa. Approximately 10 percent of the species are parasites of vertebrates —several species, most of which are opportunistic, can infect humans, in whom they can cause microsporidiosis.
Crithidia is a genus of trypanosomatid Euglenozoa. They are parasites that exclusively parasitise arthropods, mainly insects. They pass from host to host as cysts in infective faeces and typically, the parasites develop in the digestive tracts of insects and interact with the intestinal epithelium using their flagellum. They display very low host-specificity and a single parasite can infect a large range of invertebrate hosts. At different points in its life-cycle, it passes through amastigote, promastigote, and epimastigote phases; the last is particularly characteristic, and similar stages in other trypanosomes are often called crithidial.
Intracellular parasites are microparasites that are capable of growing and reproducing inside the cells of a host. They are also called intracellular pathogens.
Visceral leishmaniasis (VL), also known as kala-azar or "black fever", is the most severe form of leishmaniasis and, without proper diagnosis and treatment, is associated with high fatality. Leishmaniasis is a disease caused by protozoan parasites of the genus Leishmania.
Leishmania major is a species of parasite found in the genus Leishmania, and is associated with the disease zoonotic cutaneous leishmaniasis. L. major is an intracellular pathogen which infects the macrophages and dendritic cells of the immune system. Though Leishmania species are found on every continent aside from Antarctica, Leishmania major is found only in the Eastern Hemisphere, specifically in Northern Africa, the Middle East, Northwestern China, and Northwestern India.
Alan Hutchinson Fairlamb, CBE, FRSE, FLS, FMedSci, FRSB is a Wellcome Trust Principal Research Fellow and Professor of Biochemistry in the Division of Biological Chemistry and Drug Discovery at the School of Life Sciences, University of Dundee, Scotland. From 2006-2011 he was a member of the Scientific and Technical Advisory Committee of the Special Programme for Research and Training in Tropical Diseases (TDR) -- an independent global programme of scientific collaboration co-sponsored by UNICEF, UNDP, the World Bank and WHO. Currently he is a member of the governing board of the Tres Cantos Open Lab Foundation, whose aim is to accelerate the discovery and development of medicines to tackle diseases of the developing world in an open collaborative manner.
Protozoan infections are parasitic diseases caused by organisms formerly classified in the kingdom Protozoa. These organisms are now classified in the supergroups Excavata, Amoebozoa, Harosa, and Archaeplastida. They are usually contracted by either an insect vector or by contact with an infected substance or surface.
Leishmania donovani is a species of intracellular parasites belonging to the genus Leishmania, a group of haemoflagellate kinetoplastids that cause the disease leishmaniasis. It is a human blood parasite responsible for visceral leishmaniasis or kala-azar, the most severe form of leishmaniasis. It infects the mononuclear phagocyte system including spleen, liver and bone marrow. Infection is transmitted by species of sandfly belonging to the genus Phlebotomus in Old World and Lutzomyia in New World. The species complex it represents is prevalent throughout tropical and temperate regions including Africa, China, India, Nepal, southern Europe, Russia and South America. The species complex is responsible for thousands of deaths every year and has spread to 88 countries, with 350 million people at constant risk of infection and 0.5 million new cases in a year.
Leishmania tropica is a flagellate parasite and the cause of anthroponotic cutaneous leishmaniasis in humans. This parasite is restricted to Afro-Eurasia and is a common cause of infection in Afghanistan, Iran, Syria, Yemen, Algeria, Morocco, and northern India.
Leishmania mexicana is a species of obligate intracellular parasites of the protozoan genus Leishmania. In Mexico and Central America, this parasite is the primary cause of cutaneous leishmaniasis.
Paleoleishmania is an extinct genus of kinetoplastids, a monophyletic group of unicellular parasitic flagellate protozoa. At present it is placed in the family Trypanosomatidae. The genus contains two species, the type species Paleoleishmania proterus and the later described Paleoleishmania neotropicum.
Angomonas deanei is a flagellated trypanosomatid protozoan. As an obligate parasite, it infects the gastrointestinal tract of insects, and is in turn a host to symbiotic bacteria. The bacterial endosymbiont Ca. "Kinetoplastibacterium crithidii" maintains a permanent mutualistic relationship with the protozoan such that it is no longer able to reproduce and survive on its own. The symbiosis, subsequently also discovered in varying degrees in other protists such as Strigomonas culicis, Novymonas esmeraldas, Diplonema japonicumand Diplonema aggregatum are considered as good models for the understanding of the evolution of eukaryotes from prokaryotes, and on the origin of cell organelles.
Phytomonas is a genus of trypanosomatids that infect plant species. Initially described using existing genera in the family Trypanosomatidae, such as Trypanosoma or Leishmania, the nomenclature of Phytomonas was proposed in 1909 in light of their distinct hosts and morphology. When the term was originally coined, no strict criterion was followed, and the term was adopted by the scientific community to describe flagellate protozoa in plants as a matter of convenience. Members of the taxon are globally distributed and have been discovered in members of over 24 plant families. Of these 24, the two main families that are infected by Phytomonas are Euphorbiaceae and Asclepiadiacae. These protists have been found in hosts between 50° latitude North and South, and thus they can be found on all continents save for Antarctica.
