Читать книгу Parasitology - Alan Gunn - Страница 79

Several species in this genus parasitize wild and domestic animals, but the most well known is Theileria parva, which causes East Coast fever (theileriosis) in cattle in sub‐Saharan Africa. Other important species include Theileria annulata that also parasitizes cattle and Theileria hirci that infects sheep and goats – these species occur in parts of North Africa, the middle East, Europe, and Asia. Theileria parasitize red blood cells, lymphocytes, and tissue macrophages (histiocytes), and they are common causes of disease and potentially fatal infections in their mammalian hosts. Unlike the genus Babesia, the genus Theileria does not include zoonotic species. They are all transmitted by Ixodidid ticks (so‐called hard ticks) and are therefore examples of tick‐borne diseases.

The genera Theileria and Babesia belong to the order Piroplasmida and hence these parasites are referred to as piroplasmids. The genomes of Theileria species exhibit important differences from other apicomplexans (Nene et al. 2016). For example, although the T. parva genome is much smaller (36.5%) than that of P. falciparum, it contains 76.6% of the number of genes encoding proteins. This means its genes are packed extremely closely together. In addition, some metabolic pathways are abbreviated/absent, which indicates considerable metabolic dependence upon the host.