Investigation Of Swine Coccidia Infection In Large-Scale Swine Farms In China

Swine coccidiosis is a host-specific protozoa disease caused by the Cystoisospora suis and Eimeria spp.in swine intestinal epithelial cells,resulting in diarrhea or subclinical symptoms.In swine production,many managers did not pay enough attention to coccidiosis,resulting in serious economic losses.In order to understand the incidence of swine coccidiosis,the epidemic characteristics and the genetic characteristics different species of swine coccidia in large-scale swine farms in some areas of China.In this study,fresh fecal samples of swine from 23 regions of 7 provinces in China were collected to investigate coccidiosis,species identification and genetic characteristics analysis of coccidia oocysts in feces were conducted by combining morphological identification and molecular biological identification,aiming to provide scientific basis for accurate prevention and control of coccidiosis in China.1.Investigation on the prevalence of swine coccidiosis in large-scale pig farms in some regions of China.In this study,3306 fresh swine feces samples were collected from 23 regions in 7provinces of China(Henan,Shaanxi,Shandong,Jiangsu,Jiangxi,Fujian,Guangdong).The infection rate and infection intensity of swine coccidia in different regions,age,seasons,and farm mode were determined by washing precipitation method and saturated sucrose flotation method.The results showed that,the infection rate of swine coccidia was 13.88%(459/3306),and the average infection intensity OPG was 1.3×104(1×102-2.7×106).The highest infection rate was 34.63%(107/309)in Guangdong,and the lowest was 4.08%(49/1201)in Shaanxi.Swine at 0-28 d had the highest infection rate 25.53%(120/470),and the average infection intensity was the highest.Pigs at 64-168 d had the lowest infection rate 7.93%(47/593),and the average infection intensity was the lowest.The infection rates in summer and autumn were 11.99%(117/976)and 20.31%(213/1049),respectively.The infection rate was18.31%(297/1622)and the average infection intensity was the highest in the two-point breeding mode,while the infection rate was 8.50%(125/1470)and the average infection intensity was the lowest in the three-point farm mode.2.Morphological identification of Coccidia from large-scale pig farms in some regions of China.In this study,positive 459 fecal samples of coccidia oocysts tested under microscope were sporoidized,and morphological identification of coccidia were conducted under microscope.Based on the morphological information of coccidia oocysts recorded,the identification keys of swine coccidia was made,and a total of 9 species of coccidia of two genera were identified.They were 8.20%(271/3306)of Cystoisospora suis,2.84%(94/3306)of Eimeria debliecki,2.75%(91/3306)of Eimeria neodebliecki,2.30%(91/3306)of Eimeria perminuta,3.30%(109/3306)of Eimeria polita,2.24%(74/3306)of Eimeria porci,0.45%(15/3306),2.27%(75/3306)and 1.72%(57/3306)of Eimeria scabra,Eimeria spinosa and Eimeria suis,respectively.With dominant species Cystoisospora suis.This results showed that the infection situation was different in different provinces,ages,seasons and farm mode.The infection rate of single species was 8.20%(271/3306),and that of mixed species was 5.69%(188/3306).The infection rates of 2,3,4,5,6 and 7 Eimeria species were0.24%(8/3306),0.91%(30/3306),0.70%(23/3306),1.63%(54/3306),0.30%(10/3306)and1.91%(63/3306),respectively.Among them,the infection rate of single coccidia was the highest,followed by the infection rate of mixed infection of 7 coccidia.3.Molecular biological identification of single oocyst of swine coccidiaIn this study,Cystoisospora suis from 23 regions and 8 species of Eimeria spp.were isolated by single oocyst isolation technique,and the whole genome DNA of single oocyst was extracted.Based on the sequence analysis of the SSU r RNA and ITS r RNA gene loci of the Cystoisospora suis,the results showed that: The interspecific sequence homology of 23 strains of Cystoisospora suis were 99.80%-100.00% and 100.00%,respectively.Phylogenetic analysis showed that there was no genetic variation in Cystoisospora suis in 23 regions.The sequence analysis of SSU r RNA and COX Ⅰ gene loci of Eimeria spp.showed that the interspecific sequence homology of 8 Eimeria species was 96.10%-99.90%.Phylogenetic analysis revealed the evolutionary relationships between the 8 species and other animal coccidia.The eight coccidia species can be accurately distinguished by the combination of morphological and molecular methods.In this study,the infection situation of swine coccidia in some regions of China was analyzed.The results showed that the infection rate,infection intensity and infection type of swine coccidia were different in different areas,age,seasons and farm modes,and most of them were mixed infections.Cystoisospora suis are the main species to harm piglets and should be paid more attention to.Based on SSU r RNA,ITS r RNA and COX Ⅰ gene loci,the isolated oocysts of swine coccidia were studied,which not only provided the infection situation and epidemiological data of swine coccidia,but also provided the identification method combining morphology and molecular biology for swine coccidia studies in various regions of the world,and provided convenience for practical production and application.