Epidemiological Investigation And Control Of Colibacillosis In Large Scale Pig Farms In Hunan Province

With the continuous improvement of the level of pig breeding in China recently,the pig breeding mode has gradually changed from free range breeding to large-scale and intensive breeding modes.However,pigs in large-scale and intensive breeding farms are easy to be suffered from epidemic diseases in the breeding process.And even some of pathogens can infect people,which poses huge threats to human and animal health,and also causes economic losses to the farms.Escherichia coli(E.coli)is a species of Gram-negative bacteria,which is common in the environment of pig farms.The clinical symptoms of pigs infected with E.coli are complex,which mainly include diarrhea,sepsis and edema disease of pigs.Enterotoxigenic Escherichia coli(ETEC)is an important pathogen leading to diarrhea of piglets,and it poses a potential threat to the health of workers in pig farm.In order to preliminarily investigate the epidemic characteristics of Colibacillosis in large-scale pig farms in Hunan Province,1015 specimens from some large-scale pig farms in Xiangtan,Yiyang and Loudi areas of Hunan Province from 2016 to 2018 were collected to investigate investigated the prevalence and drug resistance of ETEC,through bacterial isolation and culture,Gram staining and PCR methods.Meanwhile,the effect of Chinese herbal compound preparation on Colibacillosis was also investigated.Finally,the diagnosis and treatment of a case of E.coli infection characterized with swine edema disease were described,and the corresponding comprehensive prevention and control measures were put forward.The specific test results are as follows:From March 2016 to September 2018,1015 samples were collected from 6 large-scale pig farms in some areas of Hunan Province,which include 580 pig feces samples,108 aerosol samples,94 sewage samples,142 tool swab samples and 91 feed samples,respectively.ETEC was isolated and identified by a series of laboratory diagnostic techniques and and tested for drug sensitivity selection.The results showed that 194 strains of ETEC were isolated from 1015 samples with the positive rate of 19.11%.The detection rates of ETEC in feces,aerosol,sewage,utensil swab and feed samples were 21.90%(127/580),17.59%(19/108),22.53%(24/94),14.08%(20/142)and 4.40%(4/91),respectively.The results of further drug sensitivity tests showed that the drug resistance rate of the strains to kinds of common antibiotics was 3.33～96.67%,of which sulfamethoxazole and ciprofloxacin were highly resistant,the drug resistance rates were93.33% and 96.67% respectively,and ceftiofur and polymyxin B were relatively sensitive,with the drug resistance of were 23.33% and 3.33%,respectively.Chinese herbal compound preparation(compound preparation)were added to the basic diet of piglets in different proportions(0.1%,0.2% and 0.4%),to investigate its roles in the growth of weaning piglets and its control and prevention of Colibacillosis in pigs.The results showed that compared with the antibiotic control group,adding different proportion of compound preparation in the feed could increase the average daily feed intake and average daily weight gain of weaned piglets,and reduce the corresponding feed to meat ratio,in which the best proportion was 0.2%.In addition,the treatment effect of 0.2% compound preparation on Colibacillosis was basically the same as that of antibiotic group,and the survival rate was 83.33%(20/24).While the combination of compound preparation and antibiotic could effectively improve the survival rate of infected pigs,which was 95.83%(23/24).The results showed that the appropriate proportion of compound preparation in the diet was not only beneficial to the growth and development of piglets,but also the combination of which with antibiotics can improve the cure rate of swine Colibacillosis and reduce the frequent use of antibiotics.In the process of experimental investigation,we found a typical case of edema disease caused by E.coli infection in nursery pigs.Through clinical observation and laboratory diagnosis,the results showed that the occurrence of edema disease in nursery pigs was mainly caused by E.coli infection,and the specific reason was that the water source of the farm was polluted by E.coli and the stress induced by environment change.Before the diagnosis of the pathogen,the infected pigs were fed the basic diet containing 0.2%compound preparationa and treated with Levofloxacin,while the treatment effect was poor.and then the pigs were given the corresponding antibiotic(Ceftazidime)treatment according to the results of drug sensitivity test,which quickly inhibited the prevalence of E.coli infection.At the same time,we developed a comprehensive prevention and control plan for the pig Colibacillosis: strictly disinfect the water source,regularly clean and disinfect the pig house,regularly monitor the pig Colibacillosis in the farm,and add 0.2% compound preparation in the pig feed for the prevention and control of the disease.