Research On The Eradication Of CSF And PR In A Large Scale Pig Farm

Classical swine fever(CSF) is a highly contagious disease of pigs caused by classical swine fever virus which belongs to Flaviviridae,Pestivirus.CSF is one of notifiable diseases to Office International des Epizooties(OIE).Recently,CSF's clinical symptoms and pathological changes are becoming complicated and unidentified.Sometimes it may be mixed with other diseases. Mature pigs always reveal mild clinical symptoms such as difficult on breed and so forth. During these types,the ratio of difficult on breed is raising,its clinical symptoms are often as abortion,stillbirth,mummified fetus,weak fetus and even some fake health fetus.All above situations caused heavy economic losses.Pseudorabies(PR) is cause by Pseudorabies virus(PRV).Its classical symptoms mainly include fever and encephalomyelitis.However,inapparent infection is a mainly symptoms in matured pig groups.It is remarkable that matured female pigs often reveal the symptom of difficult on breed.The PRV also caused fetus encephalomyelitis,septicemia even heavily diarrhoea.So,these all caused pig industry heavy economic losses.Nowadays,There are effective vaccines with good quality to control both diseases.During them,C strain which developed by China has many virtues such as persistent immunity,heritage stabilization,no remain virulence etc.It's considered as one of most effective CSF vaccine.To PRV,a special vaccine which without gE gene has becoming more and more mature.It is easy to identify vaccine strain from wild strains with relative test kit.For the effort of vaccines,some states have eradicate CSF and PR,however,CSF and PR sometimes outbreak in China although the same vaccines also applied in our country.There are some reason may answer the question. Firstly,our economic situation limits large scale eradication actions.Moreover,virus' mutation, managemem in a mess,incomplete immune program for CSF and PR and complicated situation of pig and other pathogens are also the reasons to the question above.During them,the complicated situation of pig and virus often caused hard to distinguished CSF and PR from other diseases.Nowadays,there are kinds of matured test facilities in a lab,but,it's hard to generalize them for many reasons.It delayed the diseases' diagnosis.This research mainly focus on those shortcomings above,firstly,we choose a set of test methods from all matured CSF and PR testing methods which should contain such merits as specific,easy to operate and low cost.The second step is to process a scientific epidemiology investigation with those methods.At last,we hope get some experiences and generalized them from this process.In the same time,we also analyzed the bad aspects,corrected them with some experiments.The final aim is to eradicate both diseases from pig farms.The result:accomplished the selection of CSF and PR's test methods.To CSF's test,we choose RT-nPCR as antigen detective method and IDEXX E2 kit as antibody method.It is the first time to have all vitro-samples selected and we choose blood as detective sample eventually.To PR, we choose IDEXX gE kit and IDEXX gB kit as antigen and antibody's test methods respectively.To select a suitable large scale pig farm to processing our research,we design a new isolation pigsty at beginning.It reveals effect that we once detect a strain PRRS virus from boars which are newly introducted.According the EPDML history and sampling investigation,we establish a good sampling program and finished CSF and PR's investigation with it.The result is that positive ratio in female pig group is 89.2%(893/1001) and in boars is 93.2%(69/74).The RT-nPCR's result is that both normal female and boar's blood samples are negative.However, there is one sample from abnormal pig is detected as positive We decide to control CSF's epidemic with the antibody blocking ration method.Firstly,the blocking ration range is 56%-95%.To cull both fringe group which far from blocking ration range.At last,it reveal that antibody's positive ratio is little higher than before and RT-nPCR's result is negative. The result of IDEXX gE test is that the positive ratio in female pig group is 60.7%(608/1001);in boars is 44.6%(33/74).It illustrate that there has PRV's epidemic.Analyzing all aspects of the result,it reveals that PRV's epidemic is relative with date that female pig in farm(P＜0.01). According to above,we do such experiments as follow:1) To make sure whether there exist PRRS and PCV-2 with relative PCR methods.It reveals that there do exist PCV-2.2) Find that the PR's vaccine has changed once when we investigate the history of the farm.Thus,we first change the vaccine in a small group to make sure whether the vaccine is safe and whether the action is effect.The result is that both small group and large scale's generalized is successful.In large scale,the positive is 73%(29/40):08.7;65%(21/33):08.8;47%(22/47):08.9; 44%(24/53):08.10;41%(16/39):08.11;42%(11/26):08.12;30%(8/27);09.1,2.It illustrate that the control and eradication program which including the vaccine's change,negative boar group's establishment are useful.