Investigation Of Giardia Duodenalis Infection In Dairy Cows On Large-scale Cattle Farms From Some Areas Of Xinjiang

Giardia duodenalis is a common zoonotic parasitic protozoan.According to the host specificity and genetic specificity,it is divided into 8 types of assemblages(A-H).In this study,microscopic observation and PCR methods were used to detect and identify Giardia duodenalis in large-scale dairy cows in some areas of Xinjiang,aiming to grasp its prevalence and the distribution characteristics of assemblages.1.In total,749 cow feces samples from 5 large-scale cattle farms in Alar City,Hutubi County and Tiemenguan City were collected and were examined by using the Sheather’s sugar floating technique and Lugol’s iodine solution staining technique.The results showed that the total infection rate of intestinal parasites in dairy cows was 29.8%(223/749).Five types of eggs/oocysts were identified.Coccidia oocyst was the dominant infection type,and the infection rate was 26.4%(200/749).The infection rates of sporeworm,Giardia,Trichuris trichura and Strongylus were 3.9%(29/749),3.7%(28/749),0.1%(1/749)and 0.1%(1/749),respectively.Among different farms,the infection rate of intestinal parasites in dairy cows in the Alar 3 farms was the highest,55.6%(79/142),and the infection rates in Alar 1,Alar 2,Hutubi and Tiemenguan were 33.1%(52/157),26.2%(38/145),17.3%(26/150)and 18.1%(28/155)respectively.Among different age groups,the infection rate of intestinal parasites in dairy cows aged 7-12 months is the highest,44.6%(66/148),<2 months old,3-6 months old,13-24 months old and ≥25 months old The infection rates of intestinal parasites in dairy cows were 26.1%(40/153),32.7%(49/150),29.1%(43/148)and 16.7%(25/150)..2.Based on the SSU r RNA gene locus,749 fecal DNA samples were detected by Nest PCR,and 180 positive samples were found to be Giardia duodenalis.and the total infection rates is 24.0%(180/749),which was higher than the result of microscopy.The infection rates of Giardia duodenalis in dairy cows at Tiemenguan was the highest,45.8%(71/155);the infection rates of Shituan,Wutuan,Situan and Hutubi are43.3%(69/157),0.7%(1/145),13.4%(19/142)and 13.3%(20/150)respectively.<2 months old of dairy cows have the highest infection rates of Giardia duodenalis among different age groups,is 45.1%(69/153),The infection rates of 3-6 months old,7-12 months old,13-24 months old and ≥25 months old dairy cows were 22.0%(33/150),18.2%(28/148),21.6%(32/148)and 12.0%(18/150)respectively.A total of 3assemblages were identified in 180 samples(assemblage A,B,and E).Among them,assemblage E is the dominant assemblage,but the discovery of assemblage A and B indicated that there is potential zoonotic risk in some areas of Xinjiang.The genetic distribution characteristics of Giardia duodenalis need further study.3.Based on the Giardia duodenalis Triose phosphate isomerase loci,glutamate dehydrogenase loci and β-giardin loci,the PCR method was used to identify 180 dairy cows with positive isolates of Giardia duodenalis A Multi-site sequence typing study was carried out,and 50,64,and 64 positive products were successfully amplified respectively;analysis of the obtained sequences showed that there were 11 genotypes at the tpi loci,and there are 10 in assemblage E,1 in assemblage A,8 genotypes in bg loci,7 in assemblage E,1 in assemblage A,and 13 genotypes in gdh loci,all of which are assemblage E;a total of 29 assemblage E segregation The strain was successfully amplified at 3 loci at the same time,forming 19 MLGs.The results suggest that Xinjiang dairy cattle Giardia duodenalis has diverse genetic distribution characteristics.In conclusion,dairy cows in some areas of Xinjiang are commonly infected with intestinal parasites,with coccidia being the dominant infection type;the infection rate is the highest among different age groups in 7-12 months of age;PCR results show that dairy cows in some areas of Xinjiang are commonly infected with Giardia duodenalis,The infaction rate of < 2 months old was highest;there are 3 types of assemblages(A,B and E),with assemblage E as the dominant assemblage,there is a potential risk of zoonotic disease of dairy cow Giardia duodenalis There is a genetic diversity distribution in Giardia duodenalis assemblages,and the research results provide basic data for the study of Giardia duodenalis in dairy cows in my country..