Trypanosoma equiperdum is a protozoan

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...

 that causes Dourine, or covering sickness

Covering sickness

Covering sickness, or dourine , is a disease of horses and other members of the family equidae...

, in horses and other animals in the family equidae

Equidae

Equidae is the taxonomic family of horses and related animals, including the extant horses, donkeys, and zebras, and many other species known only from fossils. All extant species are in the genus Equus...

. The donkey shows no symptoms but is a carrier of this parasite. Unlike other species of Trypanosoma, this parasite can be sexually transmitted, also mother foal transmission has been documented and does not require a vector. Can be found in genital organs and secretions.