Study On Pathogenicity Of S.boydii And Lps To Chicks

Chicken Shigella boydii disease is an acute infectious disease in recent years,diarrhea is the main feature of this disease, it can attack acutely and make the different ages and different varieties of chicken episode. But to Chick's illness and death as a primary. As information displayed, the incidence of this disease reach up to 100% in the same group,and the mortality of this disease can still reach 3.8%～33.3% after the medication. In addition, Shigella can propagate between human and poultry and cause disease. Therefore, the study on chicken Shigella boydii disease not only have important significance for animal health studies, but also with public health significance of medical.In order to provide a diagnostic criteria and clarify the mechanism of chicken Shigella boydii disease, this study ensured the pathogenicity by doing the toxicity tests using Shigella boydii and LPS on chicks. The results are as follows.1. Pathogenesis of shigella boydii to chichs of different age.Chicks of test exhibit clinical symptoms like spirit depressed, daze, appetite reduced, white loose stools and bloody stools with pus after doing the test of Shigella boydii to chicks of 3 days and 15 days. The morbidity and mortality of 3 days chicks was higher than chicks of 15 days, and hade larger difference in the conditions of same age but different method of test,where the method of intraperitoneal injection had stronger pathogenic function.The pathological changes of 15 days chicks mainly reflected in the ileum and liver, including Ileum bleeding,bowel wall thinningzed and intestinal mucosa fell off; liver congested and its surface had bleeding point; The microscopic examination showed that: epithelial cells of Intestinal shed and lamina propria hemorrhaged; interlobular venous congested, sinusoidal local expanded and seriously congested, partial liver cells had fatty degeneration.Chicks of 3 days not only had the pathological changes above, but also had typical pathological changes in rectum,lungs and spleen as below: wall of the rectum became thinner, the rectum bleeding, intestinal mucosa fell off; pulmonary venous pleonaemia; Spleen swollen and with congestion. The microscopic examination showed that: Hemorrhage in laminapropria, blood capollary of submucosa had hemorrhage; alveolus,bronchus and bronchus of respiratory had blood clot; splenic sinusoid had blood clot, many lymphocytes necrosised,the cell nucleuses soluted.2. Pathogenesis of the LPS form shigella boydii to three days chicks.Using chicks of 3 days and LPS with different concentration to do the test of toxicity, the result displayed that: the LPS of shigella boydii can make many pathological changes like necrosis and desquamate of epithelial cells in Ileal mucous membrane,hemorrhage in laminapropria, the intestinal gland had atrophy.These results indicate that: Shigella boydii of chicken can make obvious pathogenic effects on chicks of different age,but the pathogenesis is higher to younger chicks, in addition,LPS play important roles in the pathogenesis of Shigella boydii.