The prevalence of coronavirus in fecal samples of neonatal calf diarrhea using electron microscopic examination

Abstract

BACKGROUND:Neonatal calf diarrhea (NCD), also known ascalf scours, is caused by viruses, bacteria, and parasites.Coronavirus is one of the important causes of NCD syndrome.Electron microcopy has been used for demonstration of virusesin fecal samples of diarrheic calves since 1969. OBJECTIVES:The aim of this study was to determine the prevalence ofcoronavirus in fecal samples of neonatal calf diarrhea usingelectron microcopy examination of fecal samples. METHODS:For the purpose of this study, a total of 100 cases (under 2 monthsof age) of diarrheic calves from 25 commercial farms in fourdistricts of East Azerbaijan province of Iran were used. FreshFecal samples using sterile swab were collected from every calfwith clinical diarrhea. All samples were transferred into a sterilecontainer and then were sent to the laboratory to be kept in -20oCfreezer until examination. Electron microscopic examinationwas applied to all fecal samples. Chi-square test was used toanalyze the data. RESULTS:According to the results of this study,coronavirus was present in 15% of cases and a significantdifference was found between the prevalence rate and theseasons (p<0.05). The highest prevalence was recorded in winter(28%) and the least prevalence was seen in summer (4%). Therewas not any significant difference in both age groups anddifferent districts according to the prevalence rate of infection.CONCLUSIONS: Neonatal calf diarrhea is a multi-etiologicalsyndrome. Among the viral diarrhea, bovine coronavirus is oneof the major causes of this syndrome. For detection ofcoronavirus in feces, electron microscope examination is a goldstandard diagnostic technique. It seems that coronavirus can beconsidered as one of the important etiologies of neonatal calfdiarrhea in east Azerbaijan of Iran.