Gastro-enteritis is in the top 10 of afflictions in our country (4.5 million cases yearly on a population of 16 million). Well into the 20th century gasto-enteritis was important in terms of both morbidity and mortality. Globally it still is. Much more often than has been presumed before, viruses are the cause, e.g. the Norwalk-like viruses and rota virus. Main symptoms are diarrhoea and vomiting. Only in 5% of the cases the general practitioner is consulted. Risk groups are children in day-care centres and elderly in old age homes and hospices. Dangerous forms of gastro-enteritis are caused by E.coli O157 and Campylobacter. The latter can cause the Guillain-Barré Syndrome, a sometimes life threatening muscle weakness. Livestock (poultry, pigs), meat and eggs are a predominant source of intestinal pathogens. Keeping animals on a smaller scale with less intensive methods is the most logical solution to this problem.