Trypanosoma evansi
Trypanosoma evansi is a species of excavate trypanosome in the genus Trypanosoma that causes one form of surra in animals. It has been proposed that "T. evansi" is—like "T. equiperdum"—a derivative of "T. brucei". Due to this loss of part of the mitochondrial (kinetoplast) DNA "T. evansi" is not capable of infecting the invertebrate vector and establishing the subsequent life-stages. Due to its mechanical transmission "T. evansi" is not restricted to transmission via the tsetse fly but shows a very broad vector specificity including the genera "Tabanus", "Stomoxys", "Haematopota", "Chrysops" and "Lyperosia". It rarely causes disease  in humans, indeed, it has only been recorded in cases where the patient lacks a normal component of human serum, Apolipoprotein L1. "T. evansi" is very common in India and Iran and causes acute disease in camels and horses, and chronic disease in cattle and buffalo. In Pakistan, it has been found to be the most prevalent trypanosome species in donkeys. Haemoglobin plays a role in trypanolytic host defense against "T. evansi". Trypanocide resistance. "T. evansi" trypanocide resistance is widespread. Diminazene aceturate is often ineffective for bovine, equine, porcine, and elephant use in Thailand. Quinapyramine is not recommended for cattle  use due to its tendency to produce cross-resistance with both DA and isometamidium chloride. Quinapyramine is recommended for equine and camel use only. For the Philippines blanket treatment of all affected livestock is recommended, while biannual treatment of an individual village's livestock might be more financially realistic but risks developing resistance.