국내 pasteurella anatipestifer 분리주의 오리에 대한 실험병리힉적 관찰

Pathological changes in ducklings subcutaneously inoculated with pasteurella anatipestifer(Korean isolate)

The purpose of the study was pathologically to understand the pathogenecity of ducklings to a Korea isolate of Pasteurella anatipestifer (Pa) according to previous vaccination or not. One hundred eight ducklings were equally divided by six groups including 5 groups challenged with Pa after the inoculation of each killed vaccine prepared by undiluted (6×10⁹CFU/ml), ×5-, ×10-, ×20-, ×40- diluted concentrations of Pa, respectively, and one control group only inoculated with Pa without previous vaccination. Each bacterin was subcutaneously inoculated 2 times at 2 and 3-week old, and at 1 week after the final vaccination, all ducklings were subcutaneously inoculated with 0.5ml of Pa (6×10⁹CFU/ml) per head and sacrificed at 2 weeks later. Clinical signs were examined during the duration between the last vaccination and just before necropsy and all including dead and live cases during the experiment were carried out gross and histopathological examination. l. Among groups, the prevalence of clinical signs and mortality was gradually increased toward the groups inoculated with bacterins which made higher Pa-diluted concentration before challenge with Pa. Group treated with bacterin made by Pa-undiluted concentraion was no clinical signs and mortality, On the contrary, other groups with vaccination showed from 27.8% to 77.8% in clinical signs and from 11.1% to 27.8% in mortality. Control group was 100% clinical signs and 72.2% mortality. 2. Main clinical signs were early ocular discharge, greenish diarrhoea, sharp decrease of weight gain, ataxia, recumbency, torticollis, tremor of neck and death. 3. Principal gross findings were consisted of epicarditis and myocarditis, endocardial hemorrhage, increased volume of epicardial fluid with yellowish to red in colour, fibrinous airsacculitis and perihepatitis, mild splenohepatomegaly, pulmonary edema and congestion, petechiation of tracheal mucosa, and meningeal congestion and hemorrhage. 4. Main histopathological lesions comprised epicardium covered with fibrinous exudate including lots of heterophils, macrophages and homogenous eosinophilic fibrinous material, myocardium with edema, mononuclear cell infiltration and sometimes calcification in heart, diffuse vacuolar degeneration of hepatocytes and mononuclear cell infiltration in varing degrees of periportal areas in liver, mild hyperplasia of lymphocyte and reticular cells of spleen in live cases at autopy, but mild to marked deposition of eosinophilic substance and lymphocyte depletion in white pulp and compression of red pulp of spleen in dead case, mild to marked meningitis with many lymphocytes and few heterophils, perivascular lymphocytic infiltraion in brain and spinal cord, diffuse edema and congestion of interlobular space and lymphocytic hyperplasia around parabronchus of lungs. 5. Generally, the group treated with bacterin prepared by Pa-undiluted concentration prior to challenge showed milder severity and degree of pathological lesions than those in the other groups with vaccination. Grossly, the former was recorded just as 5.6% in their prevalence, but the latter was ranged from 50.0% to 88.9%.