PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF HAEMOPHILUS PARASUIS ISOLATES INVOLVED IN A MULTI-FARM OUTBREAK

摘要

Haemophilus parasuis is the causative agent of the Glasser's Disease, a syndrome that affects swine of all ages, characterized by fibrinous meningitis and polyserositis. Outbreaks involving H. parasuis occur mainly in high health or specific pathogenfree herds, where most pigs are naive to this agent. To date, 15 serotypes of H. parasuis are recognized. A high percentage (26,2%) of H. parasuis isolates is nontypeble. Serotypes 1, 5, 10, 12, 13 and 14 are believed to be the most virulent ones, whileserotypes 2, 4 and 15 are classified as moderately virulent. However, correlation between serovar and virulence has not achieved consensus in the literature. Some studies have shown that different H. parasuis strains from the same serovar can have different virulence. Phenotypic and genotypic characterization of H. parasuis isolates can be used for identification of virulent strains isolated from an outbreak. This technique may yield better information than serotyping, especially for autogenous vaccineproduction. In this report we used rep-PCR and found that only two strains of H. parasuis were involved in a large farm outbreak.