Fig. 41.—Trypanosoma evansi. × 2,000. (Original. From preparation by Fantham.)
The parasite is transmitted in nature by various species of Tabanus and Stomoxys, though at present little is known of the life-history within these invertebrate hosts.
Dogs are said to contract the disease by feeding on animals dead of surra.
A variety of T. evansi is the cause of “mbori” in dromedaries in Africa (Sahara and Sudan). Another possible variety, or closely allied form, is T. soudanense, the causal agent of “el debab” in camels and horses in North Africa, especially Algeria and Egypt.
An extraordinary example of the possible infection of a human being with an animal trypanosome is recorded in the case of Professor Lanfranchi, of the Veterinary School, Parma. The Professor became infected with trypanosomes, although only nagana and surra were maintained in his laboratory, and he himself had never visited the tropics. He suffered from irregular attacks of fever and was œdematous, but his mind remained clear. The identification of the trypanosome from Lanfranchi’s blood has been a matter of great difficulty. Apparently Mesnil and Blanchard (1914)[103] consider the strain found in the patient is almost indistinguishable in its reactions from T. gambiense, though the parasite is monomorphic. Lanfranchi considers that he was infected with T. evansi.
Trypanosoma equinum, Voges, 1901.
Syn.: Trypanosoma elmassiani, Lignières.