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

BACKGROUND:Neonatal calf diarrhea (NCD), also known as calf 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 viruses in fecal samples of diarrheic calves since 1969. OBJECTIVES: The aim of this study was to determine the prevalence of coronavirus in fecal samples of neonatal calf diarrhea using electron microcopy examination of fecal samples. METHODS: For the purpose of this study, a total of 100 cases (under 2 months of age) of diarrheic calves from 25 commercial farms in four districts of East Azerbaijan province of Iran were used. FreshFecal samples using sterile swab were collected from every calf with clinical diarrhea. All samples were transferred into a sterile container and then were sent to the laboratory to be kept in -20oC freezer until examination. Electron microscopic examination was applied to all fecal samples. Chi-square test was used to analyze the data. RESULTS:According to the results of this study, coronavirus was present in 15% of cases and a significant difference was found between the prevalence rate and the seasons (p<0.05). The highest prevalence was recorded in winter (28%) and the least prevalence was seen in summer (4%). There was not any significant difference in both age groups and different districts according to the prevalence rate of infection. CONCLUSIONS: Neonatal calf diarrhea is a multi-etiological syndrome. Among the viral diarrhea, bovine coronavirus is one of the major causes of this syndrome. For detection of coronavirus in feces, electron microscope examination is a goldstandard diagnostic technique. It seems that coronavirus can be considered as one of the important etiologies of neonatal calf diarrhea in east Azerbaijan of Iran.