Histopathological lesions in reproductive organs, distal spinal cord and peripheral nerves of horses naturally infected with Trypanosoma equiperdum.

Background: Dourine, a venereal transmitted trypanosomosis caused by Trypanosoma equiperdum, has different clinical signs related to the reproductive and nervous system. Pathologic tissue changes associated with the disease are poorly described. The present study describes the histopathological lesions in naturally T. equiperdum-infected horses in the chronical stage of dourine.

Results: Four chronically dourine diseased horses underwent a post-mortem examination. They were Woo test negative, but CATT/T. evansi positive, had a low packed cell volume (PCV) and exhibited obvious clinical signs of dourine. Post-mortem examination did not reveal gross lesions in the organs assumed to be responsible for the symptomatology. On histopathology, genital organs were affected, with mononuclear cell infiltration and erosions and degeneration of seminiferous tubules and perivascular lymphoplasmacytic cuffing in the uterus. In the nervous system, mononuclear cell infiltration was located in peripheral nerves, ganglia and in the spinal cord, leading to axonal degeneration. Real-time PCR using ITS primer revealed the presence of trypanosomes in these organs and conventional PCRs using maxicircle and RoTat1.2 primers further confirmed the involvement of T. equiperdum since the DNAs from the vagina, testicle, distal spinal cord, sciatic and obturator nerves found to be positive for maxicircle and negative for RoTat 1.2.

Conclusions: The histopathological lesions in the spinal cord and peripheral nerves explain the incoordination of the hind legs in T. equiperdum-infected horses, whilst its presence in the genital tract exemplifies the venereal transmission.