Infection of turkeys with Ornithobacterium rhinotracheale and Mycoplasma synoviae

Within 1 mo, two separate outbreaks of respiratory disease occurred in two flocks on the multiage market turkey farm in Slovenia. More severe clinical signs and higher mortality were observed in male birds. Omithobacterium rh inotracheale (ORT) was isolated in pure culture from tracheas of the affect ed birds in both outbreaks. Commercial enzyme-linked immunosorbent assay te st showed the presence of antibodies to ORT in sera of birds from both clin ically affected flocks and also in two docks of younger birds without clini cal sings. Immunoblotting with ORT culture isolated during the outbreak as an antigen confirmed the presence of antibodies to ORT in sera of turkeys o f all four flocks examined. In addition, three different serologic assays a lso detected antibodies to Mycoplasma synoviae (MS) in three out of four fl ocks. The concomitant infection with MS did not show an obvious effect on m ortality rates nor on the antibody response against ORT. Younger birds appe ared to be less susceptible to ORT pathogenicity because in those docks the infection was subclinical.