Τrypanosoma equiperdum is a species of excavate parasites that causes Dourine or covering sickness in horses and other animals in the family equidae. Genetic analyses have revealed T. equiperdum to be a derivative of Trypanosoma brucei, the causative agent of African trypanosomiasis. Unlike T. brucei, T. equiperdum is spread primarily via sexual transmission, an adaptation that has allowed it to escape beyond the range of the tsetse fly and attain a cosmopolitan distribution. Mother-foal transmission has also been documented. Τhe donkey shows no symptoms but is a carrier of this parasite. Can be found in genital organs and secretions.