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| scientific prevention and control methods of porcine epidemic diarrhea add time：2012.08.23 views：476 |
| the pathogenic porcine epidemic diarrhea virus belongs to the coronavirus family coronavirus. so far, no different serotypes have been found in the virus. the virus is sensitive to ether and chloroform. the virus concentrated and purified from the intestinal fluid of diseased piglets can not agglutinate rabbits, mice, pigs, guinea pigs, sheep, cattle, horses, chickens, and human erythrocytes. epidemiology the disease occurs only in pigs, and pigs of all ages can be infected. the incidence of suckling pigs, or feeder pig fattening pigs rate is very high, especially in the suckling pig suffer the most serious, the incidence rate of sows varies between about 15 - 90%. sick pigs are the main source of infection. the virus is found in intestinal villus epithelial cells and mesenteric lymph nodes. it is excreted by feces and contaminated with the environment, feed, water, vehicles and utensils. the main route of infection is the digestive tract. if a pig has a lot of litters of piglets born or weaned, virus will continue to lose the infection of maternal antibodies in weaned piglets, the disease is endemic, in the breeding farm, the weaning period of intractable diarrhea of porcine epidemic diarrhea can cause 5 - 8 week old piglets. the disease often occurs in cold season. pathogenesis the virus enters the small intestine directly after infection through the mouth and nose. by immunofluorescence and electron microscopy, viral replication was carried out in the cytoplasm of small intestine and colon villus epithelium. no viral proliferation was found in other organs. because the proliferation of the virus first causes cell and organ damage, and then appears the dysfunction of fine cell. intestinal villus atrophy results in the decrease of absorption surface area and the decrease of alkaline phosphatase content in intestinal mucosa, which leads to malabsorption of nutrients. this is the main cause of diarrhea and belongs to osmotic diarrhea. dehydration caused by severe diarrhea is the leading cause of death in pigs. symptom incubation period is generally 5 - 8 days, the incubation period of artificial infection is 8 - 24 hours. the main clinical symptoms were watery diarrhea, or vomiting between diarrhea. vomiting occurs after eating or after feeding. the severity of the symptoms varies with age, and the younger the symptoms. during the first 50% weeks, the piglets died of severe dehydration after 3 or 4 days of diarrhea. the highest mortality rate was 100%. sick pig body temperature normal or slightly high, depression, loss of appetite or abolishment. weaning pigs, sows are usually dispirited, anorexia and persistent diarrhea in about a week, and gradually returned to normal. a small number of pigs developed poorly after recovery. the fattening pigs had diarrhea after feeding in the same circle, and recovered after one week. the mortality rate was 1%--3%. adult pig symptoms are mild, and some only show vomiting, severe cases of water diarrhea 3 - 4 days can be self-healing. pathological changes eye changes are confined to the small intestine, dilated in the small intestine, filled with yellow fluid, mesenteric congestion, edema of mesenteric lymph nodes, and shortening of the villi. histological changes showed vacuolization and exfoliation of epithelial cells in the jejunum and atrophy of intestinal villi. the ratio of villus length to crypt crypt depth decreased from normal 7:1 to 3:1. epithelial cell shedding occurred first 2 hours after diarrhea. diagnosis the disease has no significant difference in epidemiology and clinical symptoms, but it is only slightly lower in mortality than in transmissible gastroenteritis of swine and slower in pig herds. porcine epidemic diarrhea occurs in the cold season, and can be infected at all ages. the younger the morbidity and mortality, the higher the risk of vomiting, watery diarrhea and severe dehydration, and further diagnosis depends on laboratory diagnosis prevention and cure in the popular area of this disease of pregnant sows in 2 weeks before delivery, with zhengchangsheng mix feeding, ruyuan produces antibody to stimulate, to shorten the disease in the popular home court. after the piglets were born, they took the 2-3 drops of the piglet's lifesaving liquid to take orally, which could effectively prevent the disease. |
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