Fig. 42.—Trypanosoma equinum. × 2,000. (After Laveran and Mesnil.)
Trypanosoma equinum was found by Elmassian to be the cause of the fatal disease, “mal de caderas,” of horses and dogs, in South America (Paraguay, Argentine, Bolivia). The name refers to the fact that in the disease, as in other trypanosomiases, the hind quarters become paralysed. Cattle are refractory to inoculation.
T. equinum is about 22 µ to 24 µ long and about 1·5 µ broad (fig. 42). Although this trypanosome is very active, yet it is characterized by the blepharoplast (kinetic nucleus) being very minute or even absent, as the granule sometimes seen may be the basal granule of the flagellum.
The mode of transmission of T. equinum is not known with absolute certainty. Migone has shown that the parasite causes a fatal disease in the large South American rodent, the capybara (Hydrochœrus capybara). This animal appears to be a reservoir of the parasite. Dogs may become infected by eating diseased capybaras, and it is suggested that the infection is spread from the dogs to horses by the agency of fleas. Some authorities consider that T. equinum may be spread by various Tabanidæ and by Stomoxys. Neiva (1913)[104] doubts all these modes of transmission in Brazil, and suggests Chrysops or Triatoma as vectors.
Trypanosoma equiperdum, Doflein, 1901.
Syn.: Trypanosoma rougeti, Laveran and Mesnil.
The malady of horses known as “dourine” or “mal du coït” is due to a trypanosome, T. equiperdum, discovered by Rouget in 1894. “Dourine”—also known as “stallion disease” or “covering disease”—is found among horses and asses in Europe, India, North Africa and North America. The trypanosome is transmitted by coitus, and so far as is known not by insect agency.
