Abstract
In February 1999, 5 of 11 fattening pigs in a litter on a farm in Gifu Prefecture demonstrated depression, coughing, and respiratory distress when 55 days old. Later the remaining 6 demonstrated the same symptoms. Five of the pigs died sporadically between the ages of 60 and 70 days. Necropsies showed typical pleuropneumonia in the thoracic cavity. Histopathological examination revealed severe fibrino-purulent pneumonia in 5 pigs.Actinobacillus pleuropneumoniaeserotype 1 was isolated in pure culture from the lungs of all the animals. Sera of the surviving 6 pigs were collected, and antibody responses againstA. pleuropneumoniae serotype1 isolated from the lungs of the dead pigs were examined by means of immuno-histochemical staining (IS) and the complement fixation (CF) test. IS-IgG antibodies were detected in 4 of 6 pig sera 4 days after the onset of the disease and in all sera 8 days after the onset. CF titers, on the other hand, were detected in 3 of 6 pig sera 4 days after the onset of the disease and in 4 of 6 pig sera 8 days after the onset. As a result of this study, we concluded that the IS test is more sensitive than the CF test and is a useful tool for the diagnosis of the incipient stage ofA. pleuropneumoniaeinfection.
