Nervous Tissue Lesions Caused by Elaphostrongylosis in Wild Swedish Moose

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Abstract
During the first 5 months of 1985, 35 moose were obtained for necropsy at the National Veterinary Institute, Uppsala, Sweden. 17 (49 %) of these cases were found to be infected with Elaphostrongylus sp. The nematodes were found in the epidural space of the spinal cord and brain, around and in the sciatic nerves and in muscle fasciae. Predilection sites appeared to be near cauda equina and the fasciae of the thoracic, gracilis and sartorius muscles. Most of the infected animals were calves. Both sexes were equally represented. Pathological changes found were characterized by focal haemorrhages and oedema. The changes were present in the muscle fasciae and in the leptomeninges of the brain and spinal cord. Beside infiltrates of mainly lymphocytes and plasma cells, adult nematodes, larvae and eggs were observed. Cases with mild gliosis in the cerebrum and degenerative changes of peripheral nerve roots affecting the epi- and perineurium were also found. In one case the inflammatory changes reached the endoneurium of a sciatic nerve bundle and in another case into a ganglion. Inflammatory reactions against the parasite were mainly directed towards eggs. In loose connective tissue close to nerve tissue in the central nervous system larvae were found close to eggs and remains of eggs indicating that eggs may hatch at this site. This investigation shows that natural infections with Elaphostrongylus sp. occur in wild moose and may produce pathological changes in large peripheral nerves and in the central nervous system.