Trypanosoma evansi is a protozoa

Protozoa

Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...

n trypanosome in the genus trypanosoma

Trypanosoma

Trypanosoma is a genus of kinetoplastids , a monophyletic group of unicellular parasitic flagellate protozoa. The name is derived from the Greek trypano and soma because of their corkscrew-like motion. All trypanosomes are heteroxenous and are transmitted via a vector...

 that causes one form of the surra

Surra

Surra is a disease of vertebrate animals. The disease is caused by protozoan trypanosomes, specifically Trypanosoma evansi, of several species which infect the blood of the vertebrate host, causing fever, weakness, and lethargy which lead to weight loss and anemia...

disease in animals. It has been proposed that T. evansi is - like T. equiperdum- originally a subspecies of T. brucei brucei. Due to this loss of part of the mitochondrional DNA T. evansi is not capable of infecting the invertebrate vector and establishing the subsequent life-stages
. Due to its mere mechanic transmission T. evansi is not restricted to transmission via the Tsetse-fly (glossina sp), but shows a very broad vector specificity including the genera Tabanus, Stomoxys, Haematopota, Chrysops and Lyperosia.
It rarely causes disease in humans. It is very common in India and causes acute disease in camels and horses and chronic disease in cattle and buffaloes.