An infant was brought to the casualty with complaints of watery diarrhoea and vomiting. He had mild fever. What is the MOST common cause of acute infantile gastroenteritis?

Viruses are the most common cause of acute gastroenteritis in infants. Of the viral agents causing enteric infection, rotavirus, a 67-nm double-stranded RNA virus with at least eight serotypes, is the most common. As with most viral pathogens, rotavirus affects the small intestine, causing voluminous watery diarrhea without leukocytes or blood. Rotavirus primarily affects infants between 3 and 15 months of age. The peak incidence in the winter. The virus is transmitted the fecal-oral route and survives for hours on hands and for days on environmental surfaces. Ref: Sundaram S.S., Hoffenberg E.J., Kramer R.E., Sondheimer J.M., Furuta G.T. (2012). Chapter 21. Gastrointestinal Tract. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.