The swine lungworm as a reservoir and intermediate host for hog cholera virus. I. The provocation of masked hog cholera virus in lungworm-infested swine by ascaris larvae.

Evidence that the swine lungworm can serve as reservoir and intermediate host for the hog cholera virus has been presented. The virus, however, is ordinarily carried in a masked form and must be provoked to pathogenicity by some stress before it can cause apparent disease. In the present experiments, ascaris larvae supplied the provocation needed to induce hog cholera in swine carrying lungworms infected with masked hog cholera virus. Provocation of the masked virus by ascaris larvae was seasonal in that it was effective only during a period embracing the first 5 months of the year.