Now known to be spread venereally. Infected stallions shed virus in semen for years. Trypanosomiasis Surra Dourine Equine Protozoal Myeloencephalitis Equine Babesiosis Tick borne disease Caused by either Babesia caballi or Babesia equi. Transmitted by Dermacentor, Hyalomma or Rhipicephalus species of tick. B equi is the more pathogenic of the two.
Young animals are the least susceptible to the disease.
Immunity last only a year or two. Trypanosomiasis Surra Trypanosoma evansi Africa. Trypanosoma equinum S. America. Caused by Sarcocystis neurona. A small parasitic protozoan.