Investigation And Analysis On Epidemiology Of The Hog Cholera In Huang Yuan Country

The hog cholera(HC)is a high epidemic disease caused by the hog cholera virus belonging to yellow virus family of plague virus genus. At present, the disease covering more than 40 countries in the world seriously threats to the hog industry and is listed to the first class infections.Huang Yuan county of Qinghai province in China is one of districts where the disease breaks out usually. Since the infections were found in the district in 1980, we have found not a better way to prevent it, although the three -in-one of HC was continuously injected into 95% pig for "spring and autumn" immune and the dose of the Vaccine and vaccination times increased per year. In order to research the occurrence, spread, development and variety law of HC, the paper carried out epidemiology investigation by looking up original dates of the district veterinary station about immune, annual report, quarantine, selective examination analysis report and synthetically analyzed the dates.It is showed that the incidence of HC was higher in the villages along the highway line and the disease broken out four seasons of the year because of a big margin transposition, but the peak-hour was early spring and last autumn; that the spreading form changed from the large area frequent propagate to the periodic, regional, a small amount propagate; that the symptoms of the disease taken on a diversity form and acute symptoms developed into mild symptoms. It is also showed that there was a tendency that the disease have a long incubation and course as well as a wide scope(the disease occurs both in the original and new epidemic area);that there were the untypical HC with complex diversified symptoms, continued the hog cholera virus infection, placenta infection, the innate infection of the newborn piglet, immune bearing, the reproduce obstacle of the pregnancy sow in the district. The investigation further found that the disease typical pathology changed into untypical one; that the death amount caused by the disease decreased, but the death rate was highest than other pig epidemic diseases. And HC has evolved from the single infection to the mixed infections with Salmonellosis, pasteurellosis, edema disease of piglets and Swine Erysipelas.