evidence: Diarrhoea is usually a symptom of an infection in the intestinal tract, which can be caused by a variety of bacterial, viral and parasitic organisms. Infection is spread through contaminated food or drinking-water, or from person-to-person as a result of poor hygiene. [...] Infection: Diarrhoea is a symptom of infections caused by a host of bacterial, viral and parasitic organisms, most of which are spread by faeces-contaminated water. Infection is more common when there is a shortage of adequate sanitation and hygiene and safe water for drinking, cooking and cleaning. Among children under 5 years of age, the most common viral pathogens are rotavirus, norovirus, adenovirus and astrovirus. Bacterial pathogens include Escherichia coli, Salmonella spp., Shigella spp., and Campylobacter spp., while parasitic pathogens include Cryptosporidium, Giardia, and Entamoeba spp. Rotavirus and E. coli are the most common pathogens among children across all age groups, while parasitic pathogens, are prevalent in children aged 3–5 years. Bacterial pathogens, including E. coli, Salmonella, and Shigella, were common in the children age 6 to 10-year age group, as were rotavirus, norovirus, and sapovirus. Location-specific etiologic patterns also need to be considered. [...] Other causes: Diarrhoeal disease can also spread from person-to-person, aggravated by poor personal hygiene. Food is another major cause of diarrhoea when it is prepared or stored in unhygienic conditions. Unsafe domestic water storage and handling is also an important risk factor. Fish and seafood from polluted water may also contribute to the disease.