Infants will then be followed quarterly in-clinic for the remainder of the study and will also make interim clinic visits if the child has diarrhoea. At each visit, the child will be weighed, height measured, and anthropometrics taken, including skin fold for subcutaneous body fat and mid upper arm circumference. During any symptomatic interim visits, assessments will be made of disease severity (by Vesikari scale) and a sample of stool will be collected for determination of rotavirus antigen and genotype if rotavirus positive. The patient will also be sent home with a diarrhoea diary to be completed over the following two weeks. Following identification of an child with severe gastroenteritis, an age-matched control from within the cohort (without recent gastroenteritis) will be brought in for measurement of Vitamin A and serum zinc levels. Children with gastroenteritis will be treated according to national guidelines (per WHO Integrated Management of Childhood Illness). If referral is required, the child will be referred to outpatient clinic, or in serious cases the University Teaching Hospital.