Diagnosis And Purification Of Porcine Pseudorabies In A Large-scale Pig Farm In Henan Province

Pseudorabies is a kind of highly pathogenic disease caused by Pseudorabies virus, which is harmful to swine industry all over the world. In the middle years of 20 th centruy, PR was widespread in these countries located in Eastern Europe and Balkan Peninsula. Before 1960 s,the symptom of pigs infected with PRV appeared mild and did not cause tremendous economic losses in the swine industry. However, from the 1960 s to the 1970 s, pigs of all ages can be infected and the symptom was severe, which was mainly characted with newborn piglets neurological symptoms, pig respiratory symptoms and sow abortion or stillbirth, the economic losses increased obviously. Some countries in America and European have eradicated PR, while in China, PR has been controlled effectively in past few decades, which greatly reduced the eonomic losses. However, PR was serious in many places of China since2011, due to the frequent outbreaks of PR and its severe damage on economy, exploring the rising prevalence of PR and finding the corresponding measures are the problems we must face.There was a pig farm in Henan, in which sows got severe abortion and stillbirth, and pigs of 50-70 days got neurological symptoms. According to those clinical manifestations, it was estimated Porcine Pseudorabies. To eliminate the possibility of porcine reproductive barriers and respiratory syndrome and swine fever, the ELISA and real-time fluorescent quantitative PCR were applied to examine the samples of piglets and sows. As a result of laboratory assays and diagnosis, it was diagnosed that the severe abortion and stillbirth were caused by PR.Judging from the epidemic trend of PR in a large-scale pig farm in Henan, it can be concluded what happend in the farm has certain representation. In order to eliminate these pigs infected with explicit or implicit Pseudorabies effectively, reduce the production loss,improve the health level, the investigation about PR was carried out in two branches of the pig farm(farm 1 and farm 2). The gE(PRV-gE) antibody detection has been used in those two farms, from the satistics, it can be find that the pseudorabies virus positive rate existed in those pigs like boar, multiparous sows, reserve swine in farm 1 is higher than 92%, especially mutiparous sows reached 100%, while in farm 2, the rate is higher than 87.5%, in which the boar is up to 90.48%, the multiparous sows with more than six-birth are far more high.Because of the high positive rate, it is not suitable to weed out positive pigs. Pointing to thiscondition, it was suggested that enhancing pseudorabies vaccine immunization was the good way to control and purify the PR.To explore the PR purification scheme in large-scale pig farms, the purification test has been put into effect in a farm located in Henan. The scheme is as follows: weed out those pigs with positive rate of PRV-gE in group of boar, reserve swines must have a test for PRV-gE before using and then weed out the positive. If the immune effect is unkown, strengthen immunity once for PRV-gE negative pigs. Immunization four times per year for breeding herds and a comprehensive test for PRV-gE after four months, then weed out the positive PRV-gE pigs. Piglets of 0-3 days old have their first immunity, the second time in their 50~60days; The purification scheme has been carried out to piglets which are more than 60 days, 80 days or 110 days, by detecting the PRV-gE antibody of those piglets, the results showed that after the purification in farm 1 and farm 2, the PRV-gE antibody positive rate in farm 1readuced to 0 during the fourth and fifth detection. It was proved that the purification of PR was successful. However, in farm 2, the fourth detection indicated that the PRV-gE antibody of piglets group was 0, while the fifth became positive, the positive rate was 20% for the pigs of 130 days, 27% for the pigs of 150 days and 40% for the reserve replacement sows(190days). Through the communication with technicans, it was found that the frequent technicans change caused the misoperation of vaccine immunity, that was the reason why the PRV-gE bacame positive in farm 2.Through the investigation for sick piglets of a certain swine farm in Henan. It was comfirmed that the disease was porcine pseudorabies. The result of pre-experimental serological test and purification evaluation to the two experimental filds showed that the whole herd’s antibody positive rate of PRV-gE was very high before experiment, while after the purification scheme, the rate raduced significantly and the whole herd’s antibody positive rate readuced almost 0. It can be proved that the PR control and purification in farm was a success. The successful scheme of purification was deserved to be studied, which provided valuable experience for purify the PR in domestic large-scale farms.