Trypanosoma evansi is a widely-distributed, monomorphic protozoan which infects large animals such as equines, camels, dogs, cattle and deer. It weakens cattle and buffaloes, but does not affect humans. T. evansi is the most lethal disease of camels. If untreated, it can result in up to 90% mortality among infected animals, although a partial resistance can build up. T. evansi is mechanically transmitted by blood-sucking insect species such as Tabanus, Stomoxys, Lypersoia and Haematopota. The parasites destroy red blood cells, provoking serious and often fatal anaemia.