Prevalence of coronavirus from diarrheic calves in the Republic of Korea

ABSTRACT

Objective:To investigate the prevalence of bovine coronavirus (BCoV),bovine rotavirus,and bovine viral diarrhea virus in the feces of normal and diarrheic Korean native calves aged 1-81 days between April and October of 2016 in the Republic of Korea.Methods:Samples were obtained from 50 normal and 93 diarrheic (56 semi-formed,28 loose,and 9 watery feces)calves in six different regions of northern and southern Korea.These fecal samples were tested for BCoV,bovine rotavirus,and bovine viral diarrhea virus by RT-PCR.Results:Among the three pathogens examined,infection with BCoV was especially prominent in relation to diarrhea among calves aged 1-21 days [odds ratio (OR)=9.3,95％ confidence interval (CI)1.1-78.9;P=0.02).Infection with BCoV alone (OR=2.9;95％ CI1.1-7.6;P=0.03) or coinfection of BCoV with bovine viral diarrhea virus (OR=3.6;95％ CI1.0-12.4;P=0.04) was significantly associated with the development of loose feces.Grazing and colostrum intake strongly reduced the occurrence of diarrhea as compared to housed calves (OR=0.2;95％ CI0.1-0.4;P=0.00) and calves that had not been fed colostrum (OR=0.2;95％ CI0.1-0.7;P=0.02),respectively.Conclusions:The present study suggests that BCoV is involved in calf diarrhea in the Republic of Korea.Therefore,grazing and colostrum intake is recommended for preventing and controlling calf diarrhea caused by BCoV.