Experimental Elaphostrongylus cervi infection in sheep and goats

The pathogenesis and migratory life cycle of Elaphostrongylus cervi were st udied in four sheep and sir; goats killed and examined 6 days to 5 months a fter inoculation with infective third-stage larvae (L3). Detailed histologi cal studies demonstrated that the L3 followed a porto-hepatic, and probably also a secondary lymphatic, migratory route from the abomasum and small in testine to the lungs, with subsequent spread via the general circulation to the central nervous system (CNS) and other tissues. In addition, the resul ts suggested that haematogenously spread L3, arrested in arterial vessels o utside the spinal card, migrated into the cord along the spinal nerves. Dur ing migration, the L3 caused focal inflammation and necrosis in the organs and along the spinal nerve roots, and infarcts occurred in the myocardium, kidneys and CNS. Nematode development took place in the CNS. During develop ment, there was a gradual die-off of nematodes and patent infections were n ot observed. However, in one animal many mature nematodes were demonstrated in the CNS. In the nervous system, the nematodes caused encephalomyelitis, focal traumatic encephalomalacia, gliosis, meningitis, choroiditis, radicu litis and perineuritis. Two goats and one sheep displayed long-lasting para paresis starting 6 weeks after inoculation. The signs apparently resulted f rom nematode-induced spinal nerve root lesions. From 19 weeks after inocula tion the sheep also showed signs of severe brain disturbances due to trauma tic and inflammatory lesions caused by adult E. cervi in the cerebral paren chyma. We conclude that E. cervi represents a potential cause of neurologic al disease in small ruminants grazing areas inhabited by red deer. This is the first report confirming the infectivity of E. cervi for domestic rumina nts. (C) 2000 Harcourt Publishers Ltd.