The swine lungworm as a reservoir and intermediate host for hog cholera virus. II. Attempts to demonstrate the presence of hog cholera virus in lungworms derived from swine with cholera.

Suspensions of adult lungworms, procured from swine that were outwardly healthy but derived from eggs passed by swine with hog cholera, induced this disease in a small proportion of swine into which they were injected intramuscularly. This result was achieved in both lungworm-free and lungworm-infested swine, though perhaps slightly more regularly in the lungworm-infested animals. Swine that had had an intramuscular injection of lungworm suspension and that had remained normal, developed hog cholera much more regularly following the ingestion of lungworm larvae of cholera origin than did swine not previously injected with lungworms. The findings described were markedly dependent upon season and were regularly reproducible only during the first 4 or 5 months of the year. The results presented are considered as further evidence that the swine lungworm serves as reservoir and intermediate host for hog cholera virus and that the virus is ordinarily carried by the lungworm in a masked form which must be provoked to pathogenicity by some stress before it can cause obvious disease in swine.