Investigation On The Epidemiology Of Piglet Edema Disease And Preparation Of The Inactivated Vaccine In Jilin Region

Since the first report of edema disease (ED) of piglets (Shanks, 1938), it had been assured that this disease now had taken place in nearly all porcine breeding countries around the world. This disease frequently happens to well-developed piglets in one or two weeks after weaning. Usually, it suddenly breaks out and has an incidence as high as ten to thirty percents, and the mortality is as high as ninety percents. According to the primary statistic, about 5,000 piglets would be subject to this disease and about 1,300 piglets would die of this disease in Jilin region every year. Therefore, in order to decrease the economic loss and effectively control the disease, it is necessary to investigate the epidemiology of piglet edema disease. And this work will benefit the control of piglet edema disease.In this paper, we investigated the incidence of the disease and the mortality of piglet edema in several towns of Jilin in 2006. The results demonstrated that piglet edema took place sporadically in Jilin region. The incidence of the disease in Jilin country was about 0.29-1.36 percents; the mortality was about 0.08-0.35 percents; the mortality in infected piglets was about 16.0-35.0 percents. This disease mainly happened to post-weaning piglets, occasionally to growing pig and often happened in April,May,September and October every year. 8 strains of Escherichia coli had been isolated from sick or dead piglets. They were identified as Escherichia coli by its morphology, culture and biochemical characteristics. The pathogenicity trial in mouses showed that they were all pathogenic bacteria. 8 strains were classified into 4 serotypes: O8, O139, O141, and O2. Among them, O8, O139 and O141 were the predominant sterotypes. Polyvalent inactivated vaccine was prepared with predominant-serotype E. coli. Piglets were inoculated with different dose of inactivated vaccine. The results showed that when susceptible piglets were inoculated with 6×108 CFU per piglet, these piglets would have stronger immunity. The separated bacteria were inactivated with formaldehyde and prepared into an inactivated, oil emulsion adjuvant vaccine. This vaccine had steady characteristics, without infection of bacteria. The piglets were challenged with live Escherichia coli strains through muscle after inoculation with the inactivated vaccine. The results showed that the vaccinated piglets had no abnormal clinical presentation. Evidences from clinic trials showed that the immune protective rate of the piglet edema disease reached to 97 percents for piglets in pig farm where the samples were collected, 92 percents for piglets sporadically reared in society. Regional trial showed that among 5000 piglets which were vaccinated in some parts of Jilin, the immune protective rate was over 92 percents. Those results proved the protective effect of this vaccine in practical production sufficiently, provided a basis for regional trial and application of the vaccine in large area and had important value for preventing piglet edema effectively.