Terminated due to lack of eligible patients.

Oral rehydration solution (ORS) is recommended for treatment and prevention of dehydration due to acute gastroenteritis in infants and children. Acute diarrhoea leads to zinc depletion in infants, and zinc is recommended by the World Health Organization in the treatment of acute gastroenteritis in infants and children. However, the efficacy of zinc supplementation to children with acute gastroenteritis in more affluent settings is unclear. Selected strains of probiotics, including L. reuteri ATCC 55730, have been shown in several studies to shorten the duration of diarrhoea by about 24 hours, and also to attenuate symptom severity. If probiotics are given within 60 hours from onset of symptoms the duration can be reduced even more. Lactobacillus reuteri (L. reuteri) has been shown to reduce the duration and severity of acute gastroenteritis in children aged 6-36 months. In these studies L. reuteri was proven to have clinical effect on diarrhoea of both bacterial and viral (rotavirus) origin. In humans, L. reuteri strain DSM 17938 has recently been shown to reduce the duration of watery diarrhoea by 1.2 days among 6-36 mo old Italian children with acute gastroenteritis treated in hospital.

The present, community-based study aims to assess if an ORS with Lactobacillus reuteri DSM 17938 and zinc can be superior or equivalent to ORS without probiotic and zinc in reducing the duration of acute gastroenteritis in children aged 6-36 months, with no, mild or moderate dehydration when introduced early (within 48 hours) after the start of gastroenteritis associated diarrhoea in an out-patient setting.

A prospective, randomized, double blind, controlled study with parallel groups will be performed. Assuming a difference of 25% between groups in the primary outcome of prevalence of diarrhoea 48 hours after start of treatment (80% power, alfa = 5%), and estimating an attrition rate of approximately 15%, the final sample size will be 142 subjects, or 71 subjects in each arm.

Parents contacting the health care telephone enquiry agency, the primary care emergency unit, the paediatric emergency unit, all at the Umeå University Hospital or the well-baby care centres (BVC) in Umeå for advice on their children's gastroenteritis will be informed that they may participate in the present study and they will be given contact information to the research nurse for this activity. A home visit by study personnel will then be done for evaluation of eligibility, information, collection of informed consent and delivery of study product.

Data collection points will be at the recruitment visit in the patient's home, and by telephone on day 7. If the child still has gastrointestinal symptoms on day 5 it will be referred to the primary health care facility or the outpatient clinic of the Department of Paediatrics, Umeå University Hospital.

Inclusion Criteria:

• 6 - 36 months of age
• 3 or more loose or watery stools during the past 24 hours
• Available throughout the study period
• Parents or legal guardians are able to give written informed consent to participation in the study.

Exclusion Criteria:

• Diarrhoea with a duration of >48 hours at the time of recruitment.
• Clinical signs of severe dehydration at the time of recruitment or in need of hospitalisation.
• Clinical signs of a coexisting severe acute systemic illness (meningitis, sepsis, pneumonia).
• Primary or secondary immunodeficiency.
• Severe chronic diseases including cystic fibrosis, diabetes mellitus, neurodevelopmental delay or severe gastrointestinal disorders.
• Use of probiotics in the previous 2 weeks before recruitment.
• Use of antibiotics in the previous 2 weeks before recruitment.