Studies On Pathology Of Experimental Rimerella Anatipestifer Infection

The purpose of the studies was to define the infectious type of Rimerella anatipestifer (RA) infection, to observe the dynamic pathomorphology about the two group ducklings, which were artificially infected in different age, and to observe the changes of clinical pathomorphology. The results of the studies showed as follow:1. Studies on the infectious type In the experiment, subcutaneous injection at neck was used to artificially infect 11-day-age ducklings and 17-day-age ducklings. The amount of RA and classified count about leukocyte in ducklings' peripheral blood were measured, the clinical manifestation was observed at different time after infection to define the infectious type of Rimerella anatipestifer infection. The results showed that not only in 11 -day duckling but also in 17-day duckling, the content of RA was continuous sharply increasing in a longer time after infection, and there were RA in blood during the whole experiment. Combined with clinical and pathological manifestation, it can be showed that Rimerella anatipestifer infection is a septicemia-type infectious disease, which is acute or sub-acute. Bacteriemia will occur in 12 to 24 hours after infection and it will be immediately developed to septicemia. Otherwise, the course of 11-day-age infectious duckling is acute, and the course of 17-day-age infectious duckling is sub-acute.2. Observations on the dynamic pathological changes 11-day and 17-day ducklings were killed in different time after infection to observe the gross and histological changes by conventional and special staining method. Results showed that there were serous-fibrinous or fibrinous exudates covered on the heart, liver and also be found in the air sacs in one to three days after infection, and there were continued till the end of the experiment In the course of the disease, some infectious ducklings would occur bronchopneumonia, fibrinous meningitis as well as fibrinous exudates covered the intestines and spleen. So the typical lesions of Rimerella analipestifer infection were fibrinous exudates covered the heart, liver and also be found in the air sacs. There were enormous inflammatory cell in the exudates, primarily heterophilic granulocyte, thenmonocyte and lymphocyte.3. Observations on clinical pathological changes Using routine methods, duckling' s blood biochemical indices were measured in different time after experimental infection. The results showed that, compared with the control group, red blood cells (RBC) count, hemoglobin(HB) concentration in blood, total protein (STP) and globulin(SG) concentrations and the activity of alkaline phosphatase (AKP) in serum significantly decreased. The activities of glutamic oxaloacetic transaminase (GOT) and lactic dehydrogenase (LDH) in serum significantly increased. These indicated that liver and heart were seriously damaged in infectious duckling and ducklings appear dyspepsia and anemia.4. Integrative analysis on the developing course and pathogenesis Rimerella anatipestifer infection is septicemia-type infectious disease, which is addicted to intrude into serous membarance all over the body, cause serous-fibrinous or fibrinous serous membarance inflammation. The pathogenesis is that RA firstly causes local inflammation, then rapidly break through the defensive organizations into blood. After the proliferation in blood, RA located mainly in serous membrane all over the body, cause inflammation in here and DIC and result in septicemia. Moreover, The activities of GOT, LDH significantly increased, the activity of AKP, RBC count, STP, Hb, SG concentrations significantly decreased, liver and heart were seriously damaged. Infectious ducklings appear dyspepsia and anemia, die of multiorganic functions failure and DIC in the end.