Experimental studies of Elaphostrongylus rangiferi in reindeer (Rangifer tarandus tarandus): life cycle, pathogenesis, and pathology.

A total of 12 reindeer calves (Rangifer tarandus tarandus) were given 200-1,000 infective larvae of Elaphostrongylus rangiferi and autopsied 2 1/2-196 days post inoculation (p.i.). The larvae penetrated venules of the abomasal wall and followed the bloodstream via the liver to the lungs. In the lungs the larvae entered pulmonary venules and spread to all tissues via the general circulation. Many larvae that lodged in arterial vessels outside the spinal cord migrated into the cord along the spinal nerves. Nematodes matured in the central nervous system (CNS), and then migrated to the skeletal muscles (SM) via the spinal nerve roots. Eggs were deposited into veins and carried via the venous blood to the lungs. Here, the first stage larvae hatched and entered the airways. Pathological lesions consisting of focal necroses and interstitial accumulations of inflammatory cells were observed in the abomasal wall, liver, lungs, myocardium and kidneys. Infarcts were observed in the myocardium, kidneys and CNS. Other lesions in the nervous system were encephalomyelitis, focal traumatic encephalomyelomalacia, axon and myelin sheath degenerations, meningitis, choroiditis, perineuritis, neuritis and ganglioradiculitis. A multifocal verminous pneumonia persisted from day 103 p.i., and nematode-induced inflammatory oedema was observed in the intermuscular connective tissue of the SM at 196 days p.i.