Haemophilus parasuis and Glässer's disease in pigs: a review

Haemophilus parasuis is a common epiphyte of the upper respiratory tract of pigs. The factors of H. parasuis pathogenicity that enable some strains to be virulent and consequently cause a clinical disease have not been established yet. Fifteen serovars of H. parasuis have been described at present. Individual serovars differ in virulence, and considerable differences in virulence also exist within each serovar. Virulent strains can particularly participate as microorganisms secondary to pneumonia, cause septicaemia without polyserositis or Glässer's disease characterized by polyserositis, pericarditis, arthritis and meningitis. Clinical symptoms of this disease are highly variable. Therefore, culture detection of causative agent, particularly from the brain, joints and polyserositis is an essential diagnostic tool. The disease caused by H. parasuis can be treated with antibiotics; however, oral or parenteral administration of very high doses of antibiotics is necessary. The level of animal hygiene and animal husbandry are important factors for prevention of this disease. Commercial or autogenous vaccines can be used in the immunoprophylaxis of pre-parturient sows and their progeny after weaning. For the production of autogenous vaccines, it is most effective to use isolates from animals with lesions present in CNS. Isolates recovered from arthritic and systemic sites of infection are less suitable and isolates recovered from lungs are not suitable at all because of their heterogeneity.