Porcine Hemophilus parahemolyticus pneumonia in Saskatchewan. II. Bacteriological and experimental studies.

The incidence of porcine pleuropneumonia caused by Hemophilus parahemolyticus has shown a marked increase in recent years in some countries. Isolation of a strain distinct from European serotypes was made from a natural outbreak of the disease in pigs in Saskatchewan. Experimentally infected pigs did not develop clinical signs but pathologic-anatomic studies of lungs revealed the presence of necrotizing fibrinous pneumonia with intense proliferation of mesenchymal tissue elements. Similar extensive fibroblastic activity had been found to be a typical feature in the natural infection. It is speculated that the Saskatchewan strain may have invasive patterns different from European serotypes.