Aspects of the life cycle and pathogenesis of Elaphostrongylus alces in moose (Alces alces)

Aspects of the migratory life cycle and pathogenesis of Elaphostrongylus al ces were studied in 7 randomly selected moose calves and 7 yearlings killed during August to November. One calf and 1 yearling were uninfected. The 6 infected calves had recent infections, whereas the 6 yearlings showed older infections from the summer of the previous year. The 2 calves killed in Se ptember had a total of 26 adult E. alces in the epidural space of the cauda l vertebral canal and none in the skeletal muscles, whereas the remaining c alves killed 1 to 2 mo later had 25 nematodes in the caudal and cranial ver tebral canal and 7 in the skeletal muscles. The yearlings had a total of 10 1 adult E. alces in the skeletal muscles and 2 in the vertebral canal, Ther e were no findings indicating involvement of the central nervous system in the Life cycle of E. alces. Our findings suggest that E. alces migrates dir ectly from the gut to the epidural space of the caudal vertebral canal wher e development to the adult stage takes place. During development, the nemat ode produces inflammation of the epidural tissue and spinal nerves. Develop ment in the caudal vertebral canal is followed by some anterior dispersion of nematodes along the canal, and migration into skeletal muscles. Here the nematodes seem to live in reproductive pairs and groups. The predilection site for E. alces in moose is the muscles of the thigh.