Diagnosis And Effective Evaluation Of Comprehensive Prevention And Control Of Porcine Epidemic Diarrhea In A Large-scale Pig Farm

Porcine Epizootic Diarrhea(PED)is an acute high-contact diarrheal disease caused by Porcine epidemic diarrhea Virus(PEDV).Pigs infected with PEDV show diarrhea,vomiting,and eventually dehydration.And the morbidity and mortality of piglets(affected)within 7 days of age are very high,almost 100%.In recent years,the continuous occurrence and prevalence of PED has had a significant impact on the development of the pig industry.In some large-scale pig farms,the economic loss caused by the outbreak of PED is even heavier due to the intensive development mode.This study took the diarrhea case of a large-scale pig farm in 2018 as the research object,epidemiological investigation,clinical differential diagnosis,and laboratory diagnosis were carried out for analyzing cause of the epidemic.And then the corresponding control plans are explored so as to provide reference for the prevention and control of porcine epidemic diarrhea in large-scale pig farms.1.Pathological diagnosis: In this study,a comprehensive clinical diagnosis of suspected PED,was carried out by using epidemiological methods,combined with PED colloidal gold kit and RT-PCR technology,in a large-scale pig farm in Henan Province in 2018.The results showed that the affected piglets had diarrhea,loose yellow stools,spitting up milk,getting together,depressed spirit,and slow action.The affected piglets were then emaciated,dehydrated,and eventually died of exhaustion.The necropsy results of piglets with diarrhea showed that there were no other lesions in the affected pigs except for the thinning of the intestine and the rapid yellow curd,which was in line with the clinical characteristics of PED and suggested that the pigs were infected with PEDV.76 diarrhoea piglet feces,5 suckling sow fecal samples and 5 gilt fecal swabs were all positive for PED colloidal gold kits,and further RT-PCR verified that piglets were infected by PEDV,without TGEV,PDCOV,and RV in the herd of this farm.2.Analysis of the causes of the epidemic:The clinical epidemiological analysis of the case farm showed that the causes of PED in the farm were:(1)The newly introduced gilts carried PEDV.(2)The sharing of logistics personnel and vehicles between different sections of the farm leaded to the spread of PEDV among different pig herds.(3)The pregnant sow herd lacked PED vaccine immunity,and the piglets could not obtain maternal antibody protection.This facilitated the rapid spread of the virus in lactating herds.3.Study on comprehensive prevention and control methods of epidemic diarrhea in largescale pig farms:(1)The comparison test of drug treatment of diseased piglets showed that,compared with the control and untreated group,the "antibiotic + PED yolk antibody group" had better effect than the "antibiotic group" and "antibiotic + rehydration salt group".The effective rate and cure rate("antibiotic + PED yolk antibody group")were 47.5% and 27.5%,respectively.(2)The comparison test on the selection of the return feeding time of pregnant sows showed that: compared with the control group(pregnancy sows group without return feeding),the "pregnant sows returning to feeding group 20 days before labor" was better than the "pregnancy group 10 days before labor".The diarrhea rate and death rate of its were 42.76%and 34.72%,respectively,which were significantly different from those of the control group(p < 0.05).(3)The comparative test of the implementation effect of improving comprehensive prevention measures shows that,in the large-scale pig farm,adopting timely control of the flow of personnel and materials in the farm,strengthening environmental disinfection in the farm area,urgently returning the sow herd to feed,and improving the on-site management of the lactation unit,etc.had produced obvious effects.The positive rate of PED incidence in piglets in each pig house on the farm has dropped from 96.34% to 28.49%,and the epidemic had been effectively controlled;the survival rate of piglets in each unit house had increased from 64.27% to 94.46%,with a significant difference.The above test results showed that the integrated and comprehensive control measures of early accurate and rapid diagnosis and supporting biosafety measures(returning sows + strengthening on-site management of suckling piglets + antibiotics combined with yolk antibody administration,etc.)could effectively help large-scale pigs farm with controling PED,reducing economic losses.