Fig. 4.

Transmission routes of protozoan parasites and infectious or noninfectious cancers in nature and the laboratory. Naturally, T. evansi, the cancer of T. brucei we considered, and the devil facial tumor disease (DFTD) can be mechanically transmitted by the biting of insects or the devil itself. T. equiperdum, the other cancer of T. brucei and canine transmissible venereal tumor (CTVT) can be naturally transmitted by intercourse between hosts. All strains of T. evansi, T. equiperdum, T. gondii RH, and most cancers can be mechanically transmitted from individual to individual by syringe in laboratory.