Autogenous sow vaccination for Glasser s disease in weaner pigs in two large swine farm systems

Abstract

We aimed to effectively vaccinate sows in two large farm systems suffering severe Glasser's disease in their weaner pigs. System A or B supplied 4000 or 7000 weaned pigs weekly to theit respective single-site nursery facilities. Suspect serosal lesions were cultured for Haemophilus parasuis, with serotyping and genotyping for tbpA and tbpB tiansferrin-binding genes. Most cultured H parasuis were either serotype 5 or 12 or nontypable. Specific tbpA and tbpB PCR products were further analyzed for restriction fragment length polymorphisms. This indicated that the dominant strains were genotypes bb and hg (Farm A), and aa, bb, and kf (Farm B). Selected dominant-strain cultures were expanded and formalin-killed for use as autogenous bacterins in sows 5 and 2 weeks prior to farrowing. Mortality and average daily weight gain in sheds housing progeny derived from vaccinated sows (mortality of 0.5% to 0.9% of total population) were lower than those in sheds housing nonvac-cinated progeny (mortality of 1.4% to 2.1%). Mortality due to Glasser's disease remained low 1 year after introduction of the vaccine. We concluded that tbp gene analysis is a useful additional tool for identification of dominant and potentially protective strains of Haemophilus parasuis.