Many children admitted to hospital in Botswana without bloody diarrhoea are presumed to have viral gastroenteritis and so not treated with antibiotics - but they may indeed have a treatable cause for their illness. We will conduct a randomized trial to see if rapid testing using novel methods to identify potentially treatable causes of diarrhoea leads to improved outcomes. We will also be randomizing children to probiotic therapy versus placebo (the standard of care) to see if this treatment decreases the duration of diarrhoea. The proposed study is a pilot trial, necessary before embarking on a large multi-centre trial.