Tissue migration of Elaphostrongylus spp. in guinea pigs (Cavia porcellus)

Third-stage larvae of Elaphostrongylus cervi, originating from red deer (Cervus elaphus), first reached the central nervous system (CNS) of guinea pigs (Cavia porcellus) 11 days postinfection (DPI). Neurologic signs were seen between 11 and 62 DPI in 4 of a total of 18 infected guinea pigs killed up to 112 DPI. Animals showing signs had 3 or more larvae in the CNS. Only 1, of a total of 1,114 larvae recovered, had developed to the fourth stage at 40 DPI. A direct tissue migration by third-stage larvae to the CNS was revealed by pressing and digesting almost all body tissues and by histological examination. Larvae penetrated through the stomach wall into the peritoneal cavity and then through the diaphragm into the pleural cavity. Many became encapsulated by inflammatory cells in the omentum, abdominal mesentery, mediastinum, and just beneath the liver capsule and lung pleura. A total of 44 larvae succeeded in reaching the CNS, apparently by migrating from the body cavities into muscles of the lateral body wall and entering the vertebral canal, likely along spinal nerves. Data were not consistent with a hematogenous migratory route that has been proposed previously. Few third-stage larvae of E. alces, originating from moose (Alces alces), were able to penetrate the gut of guinea pigs and none reached the CNS.