Encephalomyelitis in free-living rainbow lorikeets (Trichoglossus haematodus)

Several free-living lorikeets in three suburban flocks in eastern Australia developed bilateral paralysis, or 'clenching', of their feet. In some birds, this progressively worsened over 1 to 3 weeks to complete paralysis of their leg, body and head movements. Histological examination of the hindbrains and spinal cords of severely affected birds revealed perivascular macrophage infiltration, endothelial cell proliferation, with diffuse gliosis, astrocyte activation, neuronal necrosis, axonal degeneration and Gitter cell formation. In birds with clenched feet as the sole clinical sign, mild sciatic oedema was evident. A viral or protozoal infection may have been the inciting cause of this syndrome.