Theileria


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Theileria

 

a genus of parasitic protozoans of the family Theileriidae that parasitize cells of the reticuloendothelial system and the erythrocytes in animals.

Several species have been described as causing the disease theileriasis: T. annulata, T. parva, T. mutans, T. dispar, and T. sergenti in cattle; T. ovis, T. hirci, and T. recondita in sheep and goats; T. tarandirangiferis in reindeer; and T. cervi in other deer. T. annulata, T. sergenti, and T. tarandirangiferis are responsible for much economic damage in the USSR. Ixodids have been shown to be vectors of Theileria; the vectors of Theileria in deer have not yet been identified.

Theileria can survive in warm-blooded animals for years; in ticks, they survive for a single generation. The protozoans enter the body of a warm-blooded host with the saliva of the tick vector when the tick feeds. After reaching the nearest lymph nodes, they penetrate the reticuloendothelial cells. There they multiply by schizogony and form macroschizonts and microschizonts (Koch’s blue bodies) up to 30 micrometers in diameter and sometimes larger. They then penetrate other lymph nodes, parenchymatous organs, and the peripheral blood. Schizonts are also found outside of cells in cases of mass infection. On disintegration, a schizont produces a larger number of parasites that penetrate the erythrocytes. A single erythrocyte may contain one to four or, sometimes, more parasites. The parasites may be round (0.5–2 micrometers in diameter) or elongated (up to 4–5 micrometers long); other shapes have also been observed. The cytoplasm and nucleus of the parasite can be readily discerned in stained blood smears. The parasites reproduce in erythrocytes by dividing into two or four individuals. Theileria present in the blood of animals are the source of infection of ticks.

I. V. ABRAMOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Hatendorf et al., "Prevalence and spatial distribution of Theileria parva in cattle under crop-livestock farming systems in Tororo District, Eastern Uganda," Parasites & Vectors, vol.
Yang et al., "A PCR-RFLP Assay targeting RPS8 gene for the discrimination between bovine Babesia and Theileria species in China," Parasites and Vectors, vol.
La babesiosis fue la unica causa de origen hematopoyetico presente en los equinos estudiados, la cual es una enfermedad infecciosa febril anemizante producida por Theileria equi y Babesia caballi, trasmitida por garrapatas y otros artropodos [3, 4].
Common parasites such as Toxoplasma gondii, Plasmodium falciparum and other Plasmodium spp., Cryptosporidium parvum, and nonhuman pathogens such as Theileria and Eimeria spp.
They were lower in the Asia-Australia region than in Africa due to the fact that high intensity tick control and management methods are employed in African countries where a highly pathogenic tick-borne disease (East Coast fever caused by Theileria parva parva) is endemic [23], causing the highest cattle morbidity and mortality [24, 25].
Saberian et al., "Prevalence study of theileria annulata by comparison of four diagnostic techniques in Southwest Iran," Bulgarian Journal of Veterinary Medicine, vol.
Both Babesia caballi and Theileria equi were molecularly confirmed in camels from Iraq [6] using PCR.
The phylum Apicomplexa contains primarily obligate intracellular parasites, most notably species including Plasmodium, Babesia, Theileria, Toxoplasma, Eimeria, and Cryptosporidium.
(35.) Altug N, Yuksek N, Agaoglu ZT, Keles L Determination of adenosine deaminase activity in cattle naturally infected with Theileria annulata.