Lymphadenitis of cattle due to infection with green algae.

Abstract

Lymph nodes that were diffusely or focally green in colour were detected in cattle at slaughter in northern Australia on eight occasions over the past eight years. These lesions were caused by infection with green algae of the order Chlorococcales but specific identification of the four strains isolated was not possible in the light of present knowledge. The infection was restricted to retropharyngeal and mandibular lymph nodes in all but one instance, when a mediastinal node was also involved. The infection evoked a largely proliferative inflammatory response. Non-progressive or slowly progressive infections were established in the peritoneal cavity of rats inoculated i/p with cultures of the organism. The presence of numerous strongly periodic acid-Schiff and Gomori methenamine silver positive granules, well developed chloroplasts and the green colour of the organisms, both of individuals and colonies, serve to differentiate it from the morphologically similar Prototheca species which are probably achloric algae.