AN INVESTIGATION OF ENZOOTIC GLASSERS-DISEASE IN A SPECIFIC-PATHOGEN-FREE-GROWER-FINISHER FACILITY USING RESTRICTION-ENDONUCLEASE ANALYSIS

Enzootic Glassers's disease was investigated to study the epidemiology of the disease strains on a farm where it presented a problem. Restri ction endonuclease fingerprinting (REF) analysis technique was used, a s all strains of Haemophilus parasuis are biochemically similar and ma ny strains are biochemically untypable. After young weaned pigs were m oved from farm A to farm B, Glasser's disease routinely occurred despi te the use of antibiotics and a commercial bacterin. Isolates were tak en from the nasal passages and from carcasses of clinically affected c ases and subjected to REF analysis. Haemophilus parasuis was not isola ted from any of the pigs on farm A, but it was isolated from 7/10 and 5/10 nasal swabs taken from farm B. Two H. parasuis strains isolated f rom clinical cases of Glasser's disease from farm B had an identical R EF pattern, but were different from the nasal swabs and the H. parasui s strain contained in the bacterin. The subsequent use of a custom aut ogenous bacterin made from a clinical isolate of H. parasuis reduced t he mortality rate on farm B. This investigation indicates that nasal i solates of H. parasuis are different than those causing clinical disea se, and not all bacterin strains are cross protective for other strain s.