Epidemiological And Genotypic Research Of Giardia And Cryptosporidium In Dairy Cattle In Northwest China

As the important zoonotic protozoan parasites,Giardia and Cryptosporidium can infect human and animals through contacting directly or ingesting the contaminated food and water,and it can threaten to human health and result in significant economic losses to husbandry.Nowadays,there is no effective drug or vaccine to control giardiasis and cryptosporidiosis,hence,to investigate the prevalence and genotype distribution of Giardia and Cryptosporidium will provide basis for prevention and treatment.In the study,the fecal samples of different age stages from 19 dairy farms,in three administrative regions in Gansu province and Ningxia Hui Autonomous Region,were collected from November 2012 to March 2014,and the aim was to clarify the prevalence and the molecular characteristics of Giardia and Cryptosporidium.1.A total of 2945 fecal samples from dairy cattle were examined by using formalin-ethyl acetate precipitation,Lugol iodine staining and saturated sucrose solution float method,and the positive samples and suspected positive samples were determined by molecular biology techniques.The result indicated that Giardia could be found from 107 fecal samples,and Cryptosporidium from 150 fecal samples.The infection rate of Giardia and Cryptosporidium was 3.63% and 5.09% respectively,the highest prevalence of Giardia was 5.79% in spring,while the highest prevalence of Cryptosporidium was 6.96% in autumn;in terms of age,dairy cattle in 0-3 months age group had highest infection rate of Giardia and Cryptosporidium,which was 10.45% and 14.01%,respectively.2.In order to grasp the genetic characteristics of Giardia,the nested PCR method was applied to detect TPI gene from 107 Giardia isolates,sequencing was taken,meanwhile the sequence analysis was made by Blast in NCBI and its phylogenetic tree also was constructed by Mega software.The result showed that the target gene was successfully amplified about 530 bp from the detected samplaes,107 Giardia isolates were all Giardia intestinalis,but the differences existed in gene-type,one isolate was assemblage A,other 106 isolates were assemblage E among them.3.The SSU rRNA gene of Cryptosporidium was analyzed from 150 isolates,and sequencing and its alignment also was taken.The result showed that the aim gene was found about 830 bp according to the expected,36 isolates were identified as C.andersoni,24 isolates were C.ryanae,70 isolates were C.bovis and 20 isolates were C.parvum.In the prevalence,C.bovis was the highest.4.Additionally,the subtype of C.andersoni isolates was analyzed by MLST technique.The result indicated that 2 MLST subtypes were successfully typed from 20 isolates,involving in subtype of A4,A4,A4,A1 and A5,A4,A2,A1,and the genetic polymorphism of cow-borne C.andersoni in Gansu province was more obvious than that of Ningxia Hui Autonomous Region.In summary,calves were more easily infected by Giardia and Cryptosporidium in northwest China,but the differences existed in different seasons,the prevalence of Giardia was highest in spring,while Cryptosporidium in autumn.C.bovis and G.intestinalis were the most frequent in dairy cattle,and C.andersoni had the characteristic of genetic diversity.The supposition was made that calves was easier to be infected by Giardia and Cryptosporidium for lacking of integrated immune system.The conclusion could be made that it should strengthen the prevention and treatment of giardiasis and cryptosporidiosis.