Neuropathology of Naturally Occurring Trypanosoma evansi Infection of Horses

Abstract

Abstract. The clinical signs and pathology of the central nervous system in 9 horses with naturally occurring neurologic disease due to Trypanosoma evansi are described. The clinical course was 2 to 20 days; clinical signs included marked ataxia, blindness, head tilt and circling, hyperexcitability, obtundity, proprioceptive deficits, head pressing, and paddling movements. Grossly, asymmetric leukoencephalomalacia with yellowish discoloration of white matter and flattening of the gyri were observed in the brain of 7 of 9 horses. Histologically, all 9 horses had necrotizing encephalitis that was most severe in the white matter, with edema, demyelination, and lymphoplasmacytic perivascular cuffs. Mild to moderate meningitis or meningomyelitis was observed in the spinal cord of 5 of 7 horses. T. evansi was detected immunohistochemically in the perivascular spaces and neuropil of formalin-fixed, paraffin-embedded brain tissue in 8 of 9 horses.

Reemerging of natural infection by Trypanosoma evansi in horses in Arari, Marajó Island, Brazil

“…Microscopically, there was lymphoid hyperplasia in the spleen and systemic hemosiderosis. These findings are similar to those described by HERRERA et al (2004) andRODRIGUES et al (2009). Microscopic lesions observed in the CNS were characterized by diffuse lymphoplasmacytic encephalitis with Mott cells, similarly to the findings described by RODRIGUES et al (2005RODRIGUES et al ( , 2009.…”

“…The neurological clinical signs observed in the horses of this study are similar to those described by RODRIGUES et al (2005;2009) in the state of Rio Grande do Sul, Brazil. Ventral edema and progressive weight loss were also observed in these animals, as described in other trypanosomiasis outbreaks in horses (MARQUES et al, 2000;HERRERA et al, 2004;RODRIGUES et al, 2009).…”

“…Ventral edema and progressive weight loss were also observed in these animals, as described in other trypanosomiasis outbreaks in horses (MARQUES et al, 2000;HERRERA et al, 2004;RODRIGUES et al, 2009). Necropsy of the second horse revealed atrophy of large muscle masses, especially from the pelvic limbs, and enlarged spleen with protrusion of the white pulp.…”

“…Immunohistochemistry revealed trypomastigote specimens labeled by anti-T. evansi antibody in sections of CNS. This technique has been used in cases of natural infection by T. evansi, allowing for an association of lesions with the presence of the parasite (TUNTASUVAN et al, 2000;RODRIGUES et al, 2009).…”

“…In South America, wild animals, especially capybaras (Hidrochoerus hidrochaeris) and ring-tailed coatis (Nasua nasua), are considered important T. evansi reservoirs. Capybaras are often implicated as the source of infection in horses during outbreaks (RODRIGUES et al, 2005;RODRIGUES et al, 2009).…”