Failure of lungworm-larvae-infected earthworms to transmit mycoplasmal pneumonia to swine

Two herds of swine, believed to be free from mycoplasmal pneumonia of swine (MPS) based upon negative Mycoplasma hyopneumoniae microtiter complement fixation test (CFT) results, subsequently exhibited clinical signs of MPS.Lungworms (Metastrongylus spp.) were common to both herds. The possibility that lungworms could serve as a reservoir for M. hyopneumoniae was investigated. Lungworm-larvae-infected earthworms, collected from each of the farms, were fed to swine free of lungworms and MPS. This procedure resulted in lungworm infection in the recipient pigs, but failed to produce pneumonic lesions or CFT antibody titers against MPS.