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Mal Das Caderas, Sleeping Sickness, Trypanosoma Evansi Infection, Equine Trypanosomosis

Surra is typanosomal disease of horses, caused by infection with the prozotoal parasite, Trypanosoma evansi. The disease is characterized by weight loss, anemia, recurrent fever and eventual death in affected horses living in Asia, Africa, and South America. Although horses are the most severely affected, several other species of animals can become infected, including livestock species (pigs, cattle, goats, sheep, llamas), domestic pets (dogs, cats), and wildlife (buffalo, camels, elephants). Large outbreaks can occur among horses in areas with high populations of vector and reservoir horses.

Surra is transmitted by biting flies and vampire bats. Capybaras (a large rodent) and coatis (part of the raccoon family) are thought to act as reservoirs of the organism. Horses can sometimes develop surra as an inapparent infection, where they are capable of transmitting the disease to vectors. Trypanosomas reproduce in the blood of the vertebrate host, and the trypomastigote forms are transmitted mechanically by bloodsucking insects between animals.

Incubation period
The incubation period is 1 to 2 weeks.


Lower limb edema
Pale mucous membranes
Recurrent fever
Weight loss, despite a good appetite
Abortion in mares
Paralysis of hind limbs


  • History
  • Clinical signs
  • Physical exam
  • Laboratory tests



Report diseaseSurra is a reportable disease, meaning that if you suspect that your horse has this disease, by law you need to report it to your veterinarian, or a state or federal veterinarian.
Suramin10 mg/kg body weight, administered intravenously (IV) and repeated 1 week laterH Walden et al
Quinapyramine sulfate3 mg/kg, dose divided between two or more sitesH Walden et al
Isometamidium chloride0.25-2 mg/kg administered intramuscularly (IM)H Walden et al
MelarsomineH Walden et al
Dimazene aceturate3.5 mg/kg. 50% of treated horses and mules showed a moderate to severe adverse reaction to this treatmentH Walden et al


  • Insect repellents
  • Biosecurity


Scientific Research

General Overviews

Risk Factors

  • Horses which reside in geographic regions which have high insect populations such as hot and humid climates.

Causative agent