The Trypanosomatids are a rather large group of spindle shaped, flagellated protozoans that infect horses, livestock, and humans. Though trypanosomiasis is primarily a problem in the tropical and subtropical regions around the world the disease extends northward into Asiatic Russia and southern Europe. There are a number of different species that create slightly different clinical syndromes which are known as Dourine, Sura, and Nagana or African Animal Trypanosomiasis (AAT) however symptoms can overlap so clearly identifying the causative trypanosome may not be possible from clinical signs alone. In South America the disease is known as Mal de Caderas.

Clinical disease can vary from chronic to acute and usually typified with weight loss, anemia, and edematous swelling. In some syndromes you also will find fever, reproductive problems including swelling of the genitalia and abortion, and neurological problems. Though some species are not strongly pathogenic others can result in death. The species that infect horses do not infect humans and vice versa. Some of the diseases caused by Typanosoma sp. are:

• Human
  • Chagas, Trypanosoma cruzi, South and Central America Mexico and rarely the Southern US
  • East African and Gambian Sleeping Sickness, several species related to T. brucei, 15 o N to 25 o S (Africa): central belt from the Atlantic to the Indian Ocean coasts and from the sub-Sahara to the northern border of S. Africa
• Horse
  • Dourine, T. equiperdum, Africa, Middle East, Asiatic Russia, Central and South America. Once found widespread in North America, it has been eliminated from the US and Canada.
  • Surra, T. evansi, found throughout India, Far East, North Africa north of 15 o N; Central and South America
  • Mal de caderas, T. equinum, Central and South America
  • Sleeping Sickness or Nagana, T. brucei and other sp., 15 o N to 25 o S (Africa): central belt from the Atlantic to the Indian Ocean coasts and from the sub-Sahara to the northern border of S. Africa

This article is about the important diseases caused by trypanosmoes that effect horses. Included is geographical regions, symptoms, diagnosis, treatment and prevention.