Most people won't visit their doctor for stomach upsets, food poisoning or diarrhoea until it becomes serious or doesn't go away. Even for people that report 'stomach flu' to their doctor, only 20% are ever diagnosed in routine testing, the other 80% remain unidentified. Gastrointestinal disease can also occur in outbreaks with the cause of the outbreak often going unsolved. New DNA technologies and increased computing power now enable infectious disease researchers to find new viruses and bacteria that were previously unidentifiable. This project will find unknown viruses that cause gastrointestinal illness in New Zealand's community. Once we know what is causing illness, it will then be possible to take steps to stop people transmitting it to each other. The results from this study will be used by public health agencies to prevent or contain outbreaks through a better knowledge of these 'mystery' viruses causing such a common disease.