Stool samples were collected during a diarrhoea surveillance study conducted at the Jigme Dorji Wangchuk National Referral Hospital (JDWNRH) in Thimphu, Bhutan, between March 2011 and October 2013, as described previously (Ruekit et al., 2014). Briefly, children aged between 3 months and 5 years presenting to JDWNRH with acute diarrhoea (three or more loose stools in the previous 24 h, with symptoms lasting ≤ 72 h at time of recruitment) and those with no diarrhoeal symptoms in the previous 2 weeks were eligible for recruitment as cases and controls, respectively (informed consent permitting).