Theileria | |
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Kinete stage of Theileria parva in the transmitting tick Rhipicephalus appendiculatus | |
Scientific classification | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Alveolata |
Phylum: | Apicomplexa |
Class: | Aconoidasida |
Order: | Piroplasmida |
Family: | Theileriidae |
Genus: | Theileria |
Species | |
Theileria annulata Contents |
Theileria is a genus of parasites that belongs to the phylum Apicomplexa, and is closely related to Plasmodium . Two Theileria species, T. annulata and T. parva, are important cattle parasites. [1] T. annulata causes tropical theileriosis and T. parva causes East Coast fever. Theileria species are transmitted by ticks. [2] The genomes of T. orientalis Shintoku [3] , Theileria equi WA, [4] Theileria annulata Ankara [5] and Theileria parva Muguga [6] have been sequenced and published.
Theileria equi is a known cause of equine piroplasmosis. [7]
Vaccines against Theileria are in development. [1] [8] In May 2010, a vaccine that was reported to protect cattle against East Coast fever had been approved and registered by the governments of Kenya, Malawi, and Tanzania. [9]
Species in this genus undergo exoerythrocytic merogony in the lymphocytes, histiocytes, erythroblasts, and other cells of the internal organs. This is followed by invasion of the erythrocytes by the merozoites, which may or may not reproduce. When merogony does occur, no more than four daughter cells are produced. The frequent occurrence of elongated bacillary or "bayonet" forms within the erythrocyte is considered as characteristic of this genus.
The organism is transmitted by various tick species, including Rhipicephalus, Dermacentor , and Haemaphysalis . The organism reproduces in the tick as it progresses through its life stages. [10] Both T. annulata and T. parva induce transformation of infected cells of lymphocyte or macrophage/monocyte lineages. T. orientalis does not induce uncontrolled proliferation of infected leukocytes and instead multiplies predominantly within infected erythrocytes.
The genomes of T. orientalis Shintoku [3] , Theileria equi WA, [4] Theileria annulata Ankara [5] and Theileria parva Muguga [6] have been sequenced. Genomic data can be accessed though PiroplasmaDB which is part of the Eukaryotic Pathogen Database). [11]
The genus is thought to have first appeared in ruminants during the Miocene. It is named for parasitologist Gertrud Theiler, daughter of Arnold Theiler.
Theileria spp. can be transmitted to cattle through tick bites, including the brown ear tick, a Rhipicephalus sp.
The Apicomplexa are organisms of a large phylum of mainly parasitic alveolates. Most possess a unique form of organelle structure that comprises a type of non-photosynthetic plastid called an apicoplast—with an apical complex membrane. The organelle's apical shape is an adaptation that the apicomplexan applies in penetrating a host cell.
Babesiosis or piroplasmosis is a malaria-like parasitic disease caused by infection with a eukaryotic parasite in the order Piroplasmida, typically a Babesia or Theileria, in the phylum Apicomplexa. Human babesiosis transmission via tick bite is most common in the Northeastern and Midwestern United States and parts of Europe, and sporadic throughout the rest of the world. It occurs in warm weather. People can get infected with Babesia parasites by the bite of an infected tick, by getting a blood transfusion from an infected donor of blood products, or by congenital transmission . Ticks transmit the human strain of babesiosis, so it often presents with other tick-borne illnesses such as Lyme disease. After trypanosomes, Babesia is thought to be the second-most common blood parasite of mammals. They can have major adverse effects on the health of domestic animals in areas without severe winters. In cattle, the disease is known as Texas cattle fever or redwater.
Babesia, also called Nuttallia, is an apicomplexan parasite that infects red blood cells and is transmitted by ticks. Originally discovered by Romanian bacteriologist Victor Babeș in 1888; over 100 species of Babesia have since been identified.
Buparvaquone is a naphthoquinone antiprotozoal drug related to atovaquone. It is a promising compound for the therapy and prophylaxis of all forms of theileriosis. Buparvaquone has been shown to have anti-leishmanial activity in vitro. It can be used to treat bovine East Coast fever protozoa in vitro, along with the only other substance known – Peganum harmala. It is the only really effective commercial therapeutic product against bovine theileriosis, where it has been used since the late 1980s.
Anaplasmosis is a tick-borne disease affecting ruminants, dogs, and horses, and is caused by Anaplasma bacteria. Anaplasmosis is an infectious but not contagious disease. Anaplasmosis can be transmitted through mechanical and biological vector processes. Anaplasmosis can also be referred to as "yellow bag" or "yellow fever" because the infected animal can develop a jaundiced look. Other signs of infection include weight loss, diarrhea, paleness of the skin, aggressive behavior, and high fever.
Bovine leukemia virus (BLV) is a retrovirus which causes enzootic bovine leukosis in cattle. It is closely related to the human T‑lymphotropic virus type 1 (HTLV-I). BLV may integrate into the genomic DNA of B‑lymphocytes as a DNA intermediate, or exist as unintegrated circular or linear forms. Besides structural and enzymatic genes required for virion production, BLV expresses the Tax protein and microRNAs involved in cell proliferation and oncogenesis. In cattle, most infected animals are asymptomatic; leukemia is rare, but lymphoproliferation is more frequent (30%).
Coltivirus is a genus of viruses that infects vertebrates and invertebrates. It includes the causative agent of Colorado tick fever. Colorado tick fever virus can cause a fever, chills, headache, photophobia, myalgia, arthralgia, and lethargy. Children, in particular, may develop a hemorrhagic disease. Leukopenia with both lymphocytes and neutrophils is very common for Colorado tick fever virus. In either case, the infection can lead to encephalitis or meningitis.
Babesia microti is a parasitic blood-borne piroplasm transmitted by deer ticks. B. microti is responsible for the disease babesiosis, a malaria-like zoonosis which causes fever, hemolytic anemia caused by hemolysis and enlargened spleen.
East Coast fever, also known as theileriosis, is a disease of cattle which occurs in Africa and is caused by the protozoan parasite Theileria parva. The primary vector which spreads T. parva between cattle is a tick, Rhipicephalus appendiculatus. East Coast fever is of major economic importance to livestock farmers in Africa, killing at least one million cattle each year. The disease occurs in Burundi, Democratic Republic of Congo, Kenya, Malawi, Mozambique, Rwanda, South Sudan, Tanzania, Uganda, Zimbabwe, Zambia. In 2003, East Coast fever was introduced to Comoros by cattle imported from Tanzania. It has been eradicated in South Africa.
Piroplasmida is an order of parasites in the phylum Apicomplexa. They divide by binary fission and as sporozoan parasites they possess sexual and asexual phases. They include the tick parasites Babesia and Theileria.
Tropical theileriosis or Mediterranean theileriosis is a theileriosis of cattle from the Mediterranean and Middle East area, from Morocco to Western parts of India and China. It is a tick-borne disease, caused by Theileria annulata. The vectors are ticks of the genera Hyalomma and Rhipicephalus.
Hematozoa is a subclass of blood parasites of the Apicomplexa clade. Well known examples include the Plasmodium spp. which cause malaria in humans and Theileria which causes theileriosis in cattle. A large number of species are known to infect birds and are transmitted by insect vectors. The pattern in which Haematozoa infect a host cell depends on the genera of the blood parasite. Plasmodium and Leucozytozoon displace the nucleus of the host cell so that the parasite can take control of the cell where as Hemoproteus completely envelops the nucleus in a host cell.
Babesia bovis is an Apicomplexan single-celled parasite of cattle which occasionally infects humans. The disease it and other members of the genus Babesia cause is a hemolytic anemia known as babesiosis and colloquially called Texas cattle fever, redwater or piroplasmosis. It is transmitted by bites from infected larval ticks of the order Ixodida. It was eradicated from the United States by 1943, but is still present in Mexico and much of the world's tropics. The chief vector of Babesia species is the southern cattle fever tick Rhipicephalus microplus.
Theileria parva is a species of parasites, named in honour of Arnold Theiler, that causes East Coast fever (theileriosis) in cattle, a costly disease in Africa. The main vector for T. parva is the tick Rhipicephalus appendiculatus. Theiler found that East Coast fever was not the same as redwater, but caused by a different protozoan.
Haemosporidiasina (Haemosporidia) is a subclass of apicomplexans described by Jacques Euzéby in 1988. The taxon is very similar to Aconoidasida.
Achromatorida is an order of non-pigmented intraerythrocytic parasitic alveolates belonging to the subclass Haemosporidiasina. The order was created by Jacques Euzéby in 1988.
Ticks of domestic animals directly cause poor health and loss of production to their hosts. Ticks also transmit numerous kinds of viruses, bacteria, and protozoa between domestic animals. These microbes cause diseases which can be severely debilitating or fatal to domestic animals, and may also affect humans. Ticks are especially important to domestic animals in tropical and subtropical countries, where the warm climate enables many species to flourish. Also, the large populations of wild animals in warm countries provide a reservoir of ticks and infective microbes that spread to domestic animals. Farmers of livestock animals use many methods to control ticks, and related treatments are used to reduce infestation of companion animals.
Cytauxzoon is a genus of parasitic alveolates in the phylum Apicomplexa. The name is derived from the Greek meaning an increase in the number of cells in an animal.
Dermacentor reticulatus, also known as the ornate cow tick, ornate dog tick, meadow tick, and marsh tick, is a species of tick from the family Ixodidae. It is the type species for the genus Dermacentor. D. reticulatus is an ornate tick. The female varies in size from 3.8–4.2 mm (unfed) to 10 mm when engorged after feeding. The unfed male is 4.2–4.8 mm long. D. reticulatus is found in Europe and Western Asia, generally in wooded areas.