Larval parasites in lymph nodes of slaughter cattle

Between 1977 and 1989, evidence of parasitic infection was found in lymph node sections of twelve cattle (0.5 per cent of lymph nodes) submitted by Canadian federal meat inspectors under the tuberculosis eradication program. Macroscopically, all lesions were green foci of various sizes; microscopically, parasitic larvae were surrounded by a wide zone of eosinophils. Nine larval parasites were identified in mesenteric and one parasite in an unidentified lymph node(s). Although rare, such lesions must be defined in order to differentiate them from other aetiologies such as mycobacterial and sarcocystic granulomas.