title: Environmental source of mycobacteriosis in a California swine herd.
abstract: Between July 1985 and April 1986, mycobacterial lymphadenitis was recorded in six of 2407 slaughter pigs from a commercial swine herd in which the majority of pigs were raised in confinement. Records showed that all six affected pigs had access to dirt-floored pens at least 81 days prior to slaughter. The mycobacteriosis lesion rate for pigs exposed to dirt pens was 9.4% while in nonexposed pigs the lesion rate was zero. The risk associated with movement of pigs from concrete floored pens to dirt pens was evaluated by a field trial. In the field trial, two litters (5 of 15 pigs) exposed to dirt pens at 12-24 days of age but none of nine nonexposed litters (39 pigs) developed lesions. Mycobacterium avium-complex bacteria were recovered from both exposed litters (9 of 15 pigs) but from none of nine nonexposed litters. Serovars of M. avium-complex isolated from trial pigs included 1, 4, 8, 9, the dual serovar 4/8, and an untypable serovar. Incense-cedar bark (Calocedrus decurrens) used as a flooring material in the pens was demonstrated to be a potential source of M. avium-complex serovar 9. The dual serovar 4/8 and an untypable M. avium-complex were isolated from the dirt-floored pens. No evidence of cross-transmission of M. avium-complex infection was detected. The sporadic pattern of mycobacteriosis observed in the herd probably resulted from infrequent exposure to a common environmental source.
authors.affiliation: Department of Epidemiology and Preventive Medicine, University of California, Davis 95616.
authors.forename: I A
authors.initials: IA
authors.lastname: Gardner
authors.forename: D W
authors.initials: DW
authors.lastname: Hird
mesh_terms: D000818:Animals; D002140:California; D004783:Environmental Microbiology; D009162:Mycobacterium avium; D013552:Swine; D013553:Swine Diseases / Q000209:etiology / Q000382:microbiology*; D014376:Tuberculosis / Q000209:etiology / Q000662:veterinary*