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

Abstract

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